Let me start with something I tell every candidate who attends our UT Level II training in Bangalore.

Knowing how to perform an ultrasonic test — how to set up the instrument, calibrate the DAC curve, scan the weld, and find an indication — is half the job. The other half, equally important and far more frequently misunderstood, is knowing what to do with what you find. How long is too long? How strong an echo is too strong? When do you call a weld rejected — and when do you leave it in service?

Those questions are answered by acceptance standards. And for ultrasonic testing of welds in the ISO world, the primary acceptance standard is ISO 11666:2018 — Non-Destructive Testing of Welds — Ultrasonic Testing — Acceptance Levels.

In nearly three decades of doing and teaching UT in Indian industry, I have found ISO 11666 to be one of the most misquoted, misapplied, and misunderstood standards in the NDT practitioner’s toolkit. Engineers mix it up with ISO 17640 (the testing technique standard). They confuse its acceptance levels with those in ASME Section VIII. They apply AL2 where AL3 was specified — or vice versa — without understanding what the practical consequence is.

This article is my attempt to fix that. We will go through ISO 11666:2018 from beginning to end — the scope, the logic, the numbers, the practical application, and the relationship to every other standard in the ISO weld inspection family. By the end, you will be able to look at a UT test report referencing this standard and know exactly what it means.

What ISO 11666 Is — And What It Is Not

Before we go any further, let us establish clearly what ISO 11666 does and does not cover.

ISO 11666 tells you: Given an ultrasonic indication found during UT of a weld, what amplitude and length criteria determine whether it is acceptable or rejectable?

ISO 11666 does not tell you: How to perform the UT test. Which probes to use. How to calibrate the instrument. What scanning patterns to follow. All of those are covered by ISO 17640 — Non-Destructive Testing of Welds — Ultrasonic Testing — Techniques, Testing Levels and Assessment — which is the technique standard that ISO 11666 depends upon.

Think of it this way: ISO 17640 tells you how to look. ISO 11666 tells you what you are allowed to find. They work together — and you cannot apply one without the other. Every UT of a weld to ISO standards is a two-standard exercise: technique per ISO 17640, acceptance per ISO 11666.

Scope and Application — What This Standard Covers

ISO 11666:2018 was published in 2018 as the second edition, replacing ISO 11666:2010. As of 2025, a new committee draft (ISO/CD 11666) is under development — so a third edition is on the horizon. However, the 2018 edition remains the active international standard and is the version cited in the vast majority of current contracts and codes.

The standard applies to:

Full penetration welded joints in ferritic steels with thicknesses from 8 mm to 100 mm. This is the primary scope — the application that covers the overwhelming majority of welded pressure vessels, structural steel, pipelines, and process piping in Indian and international fabrication.

It can also be used for other types of welds, materials and thicknesses, provided the tests have been performed with necessary consideration of the geometry and acoustic properties of the component, and an adequate sensitivity can be employed to enable the acceptance levels of this document to be applied.

This second paragraph is more important in practice than the first. It is the clause that experienced practitioners use to apply ISO 11666 to austenitic stainless steel welds, aluminium alloy welds, and nickel alloy welds — always with the caveat that the UT technique must be appropriate for the material, and that adequate sensitivity to the relevant indication sizes must be demonstrably achievable.

What the standard does NOT apply to:

• Partial penetration welds — fillet welds, tee joints with partial penetration, overlay welds
• Welds in materials below 8 mm thickness (for thin section, other standards apply)
• Welds in materials above 100 mm thickness (special thick-section procedures are required)
• Austenitic stainless steel welds where specific acoustic problems preclude adequate sensitivity without specific additional provisions

The ISO Weld Inspection Standard Family — Understanding Where ISO 11666 Fits

To understand ISO 11666 properly, you need to understand the ecosystem of ISO standards it belongs to. These standards are not independent — they form a structured hierarchy.

ISO 5817:2014 — Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) — Quality Levels for Imperfections

This is the foundational document that defines what imperfection sizes and types are acceptable for different applications of welded joints. ISO 5817 defines three weld quality levels:

• Quality Level B — the highest quality; strictest limits on imperfection sizes
• Quality Level C — intermediate quality; moderate limits
• Quality Level D — the lowest quality; most permissive limits

These three quality levels are the starting point for everything in the ISO weld acceptance world. When a contract specifies “ISO 5817 Quality Level B welds”, it is saying: every weld in this project must meet the strictest permissible imperfection limits.

ISO 17640:2018 — Non-Destructive Testing of Welds — Ultrasonic Testing — Techniques, Testing Levels and Assessment

This is the testing technique standard. It defines how UT of welds shall be performed — probe selection, frequency, scanning technique, calibration, recording level, and how to determine the length of an indication. It defines four testing levels (A, B, C, and D) of increasing thoroughness, corresponding to the criticality of the application.

ISO 11666:2018 — Non-Destructive Testing of Welds — Ultrasonic Testing — Acceptance Levels

This is what we are discussing today. It takes the findings produced by a UT test performed per ISO 17640 and tells you whether those findings are acceptable or rejectable, at one of two acceptance levels that correspond to ISO 5817 quality levels.

The relationship is beautifully systematic: the quality of the weld (ISO 5817) drives the strictness of the testing (ISO 17640 testing level) which drives the strictness of the acceptance criteria (ISO 11666 acceptance level). Everything ties together.

The Two Acceptance Levels — AL2 and AL3

ISO 11666:2018 specifies two ultrasonic acceptance levels known as acceptance level 2 (AL 2) and acceptance level 3 (AL 3) for full penetration welded joints in ferritic steels, which correspond to ISO 5817:2014, quality levels B and C.

Let me be very specific about what these numbers mean and which is stricter — because this is where confusion consistently occurs.

Acceptance Level 2 (AL2) = ISO 5817 Quality Level B = The STRICTER level

Acceptance Level 3 (AL3) = ISO 5817 Quality Level C = The LESS STRICT level

The counterintuitive thing for newcomers is that a lower number (2) is the stricter acceptance level. This follows the ISO 5817 convention where Quality Level B (the best) is stricter than Quality Level C, which is in turn stricter than Quality Level D. The numbering reflects the ISO 5817 quality level letters: B = 2, C = 3.

An acceptance level corresponding to ISO 5817:2014, quality level D is not included in this document, as ultrasonic testing is generally not requested for this weld quality.

This is a logical and practical decision. ISO 5817 Quality Level D represents the most lenient weld quality — welds where relatively large imperfections are acceptable. For such welds, UT is typically not a contractual requirement because the quality level is low enough that the effort and cost of ultrasonic testing is disproportionate to the application’s criticality.

The Three Levels You Must Understand — Recording, Evaluation, and Acceptance

One of the most common sources of confusion in applying ISO 11666 is the distinction between three different amplitude thresholds that appear in the standard. These are not the same thing, and mixing them up leads to incorrect reporting.

The Recording Level (also called the Detection Level)

This is the amplitude threshold above which the technician must write the indication into the test record. Every indication that exceeds the Recording Level must be documented — its location, depth, length, and amplitude relative to the reference level. The recording level does NOT determine acceptance or rejection — it only determines what gets written down.

Per ISO 17640 and ISO 11666, the evaluation levels are expressed in dB relative to the reference DAC (Distance-Amplitude Correction) curve established from a reference reflector (typically a 3 mm side-drilled hole in the calibration block of the same material and nominal thickness as the test object).

Evaluation and Acceptance Levels

The Evaluation Level

This is the amplitude above which the technician must measure the indication’s length (using the 6 dB drop method or the specified echo-amplitude method) and assess it against the acceptance criteria. Indications above the recording level but below the evaluation level are recorded in full but their length does not need to be measured and they are not evaluated against the acceptance criteria tables.

In ISO 11666:2018, the evaluation levels for techniques 1 to 4 are given in ISO 11666:2018, Table A.1. These are expressed as dB values below the reference DAC level — typically in the range of DAC -10 dB or DAC -6 dB depending on the technique and thickness range.

The Acceptance Level

This is the maximum amplitude and maximum length that an indication may have while still being classified as acceptable. An indication that exceeds either the amplitude acceptance criterion OR the length acceptance criterion (or both) at its given evaluation level must be classified as rejectable.

Understanding the hierarchy — Recording → Evaluation → Acceptance — is the key to reading ISO 11666 correctly.

How the Acceptance Criteria Work — The Practical Application

The core of ISO 11666 is a set of tables that relate:

1. Wall thickness of the weld joint (which affects the amplitude reference level and the length acceptance criteria)
2. Amplitude of the indication (expressed in dB relative to the H0 reference level — the point on the DAC curve at the depth of the indication)
3. Measured length of the indication (determined by the 6 dB drop method or echo-amplitude method)

These three variables together determine whether an indication is accepted or rejected.

Let me work through this in practical terms.

Setting Up the Reference — What H0 Means

H0 is the amplitude reference point in ISO 11666 — it is the amplitude of the echo from the reference reflector (a 3 mm diameter flat-bottom hole or side-drilled hole, depending on the technique) at the same metal path distance as the indication being evaluated, as read from the DAC curve.

This is critical: H0 is not a fixed point on the instrument. It changes with depth. When you evaluate an indication at 20 mm depth, H0 is the DAC curve amplitude at 20 mm. When you evaluate an indication at 50 mm depth, H0 is the DAC curve amplitude at 50 mm. The DAC curve automatically accounts for sound attenuation with distance, so H0 always represents the same equivalent flaw size regardless of depth.

What the Acceptance Tables Tell You

For each combination of acceptance level (AL2 or AL3) and weld thickness range, the acceptance table gives you pairs of conditions. An indication must be evaluated against both conditions — amplitude and length — and must satisfy BOTH to be accepted.

In simplified practical terms, for a typical structural steel weld at Acceptance Level 2:

An indication is accepted if BOTH of the following apply:

• Its amplitude does not exceed H0 (the DAC curve amplitude at that depth), and Its measured length does not exceed a specified fraction of the wall thickness (typically t/4 for certain thickness ranges)

An indication is rejected if EITHER:

• Its amplitude exceeds H0 at any depth, OR
• Its length exceeds the maximum permitted regardless of amplitude, OR
• Its amplitude and length combination falls above the acceptance line in the table

The elegance of this system is that it mirrors real-world defect behaviour: large but shallow and short indications may be acceptable, while long continuous linear indications are rejectable even at relatively low amplitudes, because a long linear discontinuity (which could be a crack, a linear slag line, or a lengthy area of lack of fusion) is always more dangerous than an isolated point reflector.

The Amplitude-Length Relationship — The Key Insight

There is a principle embedded in the ISO 11666 tables that every practising UT inspector should internalise:

As an indication’s length increases, the maximum acceptable amplitude decreases.

Or stated another way: the longer the indication, the stricter the amplitude criterion. A short indication (length less than half the wall thickness, for example) may be accepted at full H0 amplitude. But a long indication — one whose length approaches or exceeds the wall thickness — must have an amplitude significantly below H0 to be accepted.

Why? Because length is a proxy for defect type and severity. A point-like porosity pore gives a short indication. A slag inclusion can give a moderate-length indication. But lack of fusion — particularly if it extends over a long run of the weld — gives a long indication. And lack of fusion, being a planar defect with potential stress-concentration effect, is far more dangerous in service than an equivalent-length chain of porosity. The amplitude-length relationship in the acceptance tables reflects this physical reality.

AL2 vs AL3 — When to Apply Which, and Why It Matters

The choice of acceptance level for a given weld is one of the most important decisions in a UT inspection contract. It is not a decision that should be made by the NDT inspector on site — it should be specified in the inspection contract, the design documentation, or the applicable product standard.

Here is the practical guidance:

Apply AL2 (the stricter level) when:

• The weld carries high stress or is in a fatigue-critical location
• The weld is in a pressure-retaining system (pressure vessels, boilers, pipelines) where failure could cause catastrophic release
• The applicable product standard or contract specifies ISO 5817 Quality Level B
• The weld joins safety-critical structural members — primary load-bearing joints in bridges, offshore platforms, or building frames
• Failure of the weld would have significant consequences for life safety or environmental integrity
• The design has been based on weld quality Level B assumptions

Apply AL3 (the less strict level) when:

• The weld is in a lower-criticality structural application
• The applicable product standard or contract specifies ISO 5817 Quality Level C
• The weld carries static (non-cyclic) loading and the design tolerates a larger imperfection
• The fabrication is categorised as standard quality rather than special quality

The critically important point: The contract or product standard determines the acceptance level. The inspector applies it — but does not choose it. If you receive a UT contract with no acceptance level specified, this must be resolved before testing begins. Applying AL3 where AL2 was required, or vice versa, is a significant quality failure — not just an administrative one. It can result in unsafe welds being accepted into service, or acceptable welds being unnecessarily rejected.

The Length Measurement Question — 6 dB Drop vs Echo-Amplitude Method

One area where ISO 11666 gives inspectors a choice — but a choice that must be consistently documented — is in the method for measuring indication length.

The 6 dB Drop Method

The probe is scanned along the weld axis until the echo from the indication drops to half its maximum amplitude (a 6 dB reduction). The distance between the two 6 dB drop positions along the scan axis is reported as the indication length. This method is straightforward, well-understood, and appropriate when the indication is reasonably distinct and not near the weld root or cap.

The Echo-Amplitude Method (DAC-based)

The inspector scans the probe along the weld until the indication amplitude falls below a specified threshold relative to H0, then reports the distance between those threshold-crossing positions as the indication length. This method tends to give shorter reported lengths than the 6 dB drop method for the same indication — which means that choosing this method rather than 6 dB drop for the same indication may be the difference between acceptance and rejection.

This is not a trick — it is a legitimate technical approach, and ISO 11666 permits both methods. But the method must be specified in the written procedure and consistently applied. An inspector who switches between methods depending on which gives a more convenient result for a marginal indication is not practising good NDT — and any competent reviewer of the test records would spot this immediately.

The Relationship with ISO 17640 Testing Levels — A Table Worth Understanding

In addition to possessing general knowledge of ultrasonic weld testing, personnel must also understand the testing challenges specifically associated with the type of welded joints under examination.

ISO 17640 defines four testing levels — A, B, C, and D — of increasing thoroughness and coverage. The choice of ISO 17640 testing level determines the scanning coverage, the probe angles used, and the number of probe positions. ISO 11666 acceptance levels are linked to ISO 17640 testing levels:

The important implication is that a contract specifying AL2 will almost certainly require ISO 17640 Testing Level B or C, because only the more comprehensive scanning coverage provided by those testing levels can reliably detect the smaller indications that AL2 is intended to control.

Conversely, a contract that specifies ISO 17640 Testing Level B but AL3 is a contract for moderately thorough scanning with moderately lenient acceptance — appropriate for secondary structural members in non-critical applications.

Transfer Correction — The Most Frequently Missed Step

Transfer differences, between test object and reference block, at a representative number of locations. ISO 16811 describes suitable techniques for this evaluation. When the differences are less than or equal to 2 dB, inspectors do not need to apply correction. The differences exceed 2 dB but remain less than or equal to 12 dB, inspectors must compensate for them. Transfer losses exceed 12 dB, inspectors must investigate the cause and carry out further preparation of the scanning surface.

This is one of the most practically significant provisions in the standard — and one of the most consistently overlooked in routine inspection work.

The calibration block has a smooth, flat surface. The inspected weld may have a rough surface due to the as-welded condition, scale, or minor corrosion. This surface roughness introduces additional sound attenuation, reducing the sound entering the weld compared with the amount that entered the calibration block. If inspectors do not measure and compensate for this transfer difference, the actual sensitivity becomes lower than assumed, causing the system to miss small indications that should have appeared above the recording level.

The correct procedure: after calibrating on the reference block, measure the DAC amplitude using the same probe on the actual weld surface at several representative locations. The difference between this reading and the calibration block reading is the transfer correction. If the difference exceeds 2 dB, inspectors must increase the instrument gain by the correction value before the test begins.

In my experience training UT Level II candidates, transfer correction is the step that separates the technician who follows a procedure from the technician who understands what the procedure is trying to achieve.

What the 2018 Revision Changed From the 2010 Edition

For those who have worked with ISO 11666:2010 and are updating their knowledge, the 2018 revision introduced several important clarifications and updates:

Clearer correlation with ISO 5817:2014: The 2018 edition more explicitly links AL2 to ISO 5817 Quality Level B and AL3 to ISO 5817 Quality Level C, making it easier to use the standard in conjunction with quality requirements specified per ISO 5817.

The revised Table A.1 aligns the evaluation level table with the updated ISO 17640:2018 technique definitions, particularly for the four standard techniques.

Expanded guidance on non-ferritic materials: The 2018 edition provides slightly more guidance on applying the acceptance criteria to non-ferritic materials where specific acoustic properties affect the validity of the reference calibration.

The 2018 edition clarifies that inspectors must establish the recording threshold before scanning begins and cannot retrospectively adjust it to change the documented results.

As of late 2024, the committee registered a new draft standard (ISO/CD 11666) to replace ISO 11666:2018 and initiated committee drafting in December 2025. The comment period closed in February 2026. This indicates that the committee is likely to publish a new edition within the next two to three years. NDT professionals working to this standard should monitor ISO’s publications for the DIS (Draft International Standard) — which will give advance notice of any significant changes to the acceptance criteria.

Applying ISO 11666 with PAUT — A Growing Practical Question

One of the questions that advanced UT practitioners ask me most frequently is whether they can apply ISO 11666 acceptance criteria to Phased Array Ultrasonic Testing (PAUT) results.

The short answer is: yes, with important conditions.

There is a document that specifies the application of the phased array technology for the semi- or fully automated ultrasonic testing of fusion-welded joints in metallic materials of minimum thickness 6 mm. It applies to full penetration welded joints of simple geometry in plates, pipes, and vessels, where both the weld and the parent material are low-alloy and/or fine grained steel.

The relevant companion standard for PAUT of welds is ISO 13588 — which covers the PAUT technique for weld inspection and references ISO 11666 acceptance levels. When inspectors use PAUT to perform weld UT in accordance with ISO 17640 technique requirements and express the results in equivalent amplitude terms relative to the same reference reflector (3 mm SDH or FBH), they can apply the ISO 11666 acceptance tables directly.

The critical condition requires the PAUT technique to demonstrate, through validation, that it achieves at least equivalent detection capability to the manual UT technique it replaces. The amplitude reference calibration must use the same reference reflector as specified for the manual technique. When PAUT produces results in S-scan or E-scan format, inspectors must properly extract the maximum amplitude at any point in the weld cross-section and compare it with the acceptance criteria.

PAUT done properly to ISO standards is a powerful tool — faster, more reproducible, and often more sensitive than manual UT for complex weld geometries. PAUT done without proper calibration and without attention to the acceptance standard requirements is just impressive-looking data that may not mean what the client thinks it means.

A Worked Example — From DAC Calibration to Accept/Reject Decision

Let me take you through a realistic scenario — the kind of situation that comes up on the shop floor regularly.

The Setup:

• Butt weld in carbon steel pressure vessel
• Wall thickness: 30 mm
• Acceptance level specified: AL2 (ISO 5817 Quality Level B)
• Testing per ISO 17640, Testing Level B
• Technique: Angle beam, 60° probe, 4 MHz, single angle
• Calibration: DAC curve from 3 mm SDH in reference block, 30 mm thickness, same material

The Calibration: You establish the DAC curve. At the 30 mm metal path depth, your DAC amplitude corresponds to the response from the 3 mm SDH. You set this as H0 at that depth. You adjust sensitivity to bring this point to 80% full screen height (FSH) — a standard reference point.

The Scan: You scan the weld. You find an indication at approximately 22 mm depth (metal path). The maximum echo amplitude from this indication is 72% FSH. You note that it exceeds the recording level, which you set below DAC—perhaps at DAC -10 dB, equivalent to about 25% FSH. You stop and evaluate.

Reading H0 at 22 mm depth: From your DAC curve, at 22 mm metal path, the DAC is — let’s say — 78% FSH. So your indication amplitude of 72% FSH is below H0. In dB terms, it is approximately 0.7 dB below H0. This means the indication is below the maximum amplitude acceptance criterion of H0.

Length Measurement: You measure the indication length using the 6 dB drop method. The amplitude drops from 72% FSH to 36% FSH (half) at two positions along the weld axis. The distance between these positions: 18 mm.

Applying the Acceptance Table

For AL2 with a 30 mm wall thickness and an indication amplitude below H0, what maximum length does the standard permit?

The ISO 11666:2018 Table gives maximum indication lengths that depend on the amplitude relative to H0 and the wall thickness. For an indication at or below H0 in a 30 mm wall, the standard typically expresses the maximum permitted length as a fraction of the wall thickness.Approximately t/2 for the amplitude level under discussion—which corresponds to 15 mm.

Our indication is 18 mm long. The acceptance criterion is 15 mm. AL2 rejects this indication.

Evaluators would need to reassess the same indication against the AL3 acceptance criteria to determine whether the less stringent level would accept it. Although that assessment remains academic from a contractual standpoint if the contract specifies AL2. It belongs in a fitness-for-service assessment, not the inspection report.

The Most Common Mistakes I See in ISO 11666 Application

After reviewing test reports and conducting audits for fabricators and inspection companies across India, these are the recurring errors:

Mistake 1 — Applying AL3 instead of AL2 because it is “easier to pass” The acceptance level is specified in the contract. Applying the wrong level — intentionally or through carelessness — is a quality system failure. Any reputable inspection company that discovers this has happened must issue a corrected report and notify the client.

Mistake 2 — Not performing transfer correction The calibration block surface is different from the weld surface. If the difference is more than 2 dB, correction is mandatory. Many inspectors on site skip this step because it adds time. It compromises the sensitivity of the inspection.

Mistake 3 — Measuring length by eye rather than by the 6 dB drop method “It looks about 15 mm long” is not a length measurement. Inspectors must use and document the 6 dB drop method or the echo-amplitude method.

other Common Mistakes That Needs Consideration

Mistake 4 — Confusing the evaluation level with the acceptance level. Inspectors must assess an indication that exceeds the evaluation level; they cannot automatically reject it. Many technicians incorrectly treat exceeding the evaluation level as a rejection. It is a threshold that triggers length measurement and acceptance assessment.

Mistake 5 — Using calibration blocks of the wrong material ISO 17640 and ISO 11666 require that the calibration block be of the same material group. As the test object.

Using a carbon steel calibration block for a 316L stainless steel weld inspection will give incorrect sensitivity because the acoustic properties differ.

Mistake 6 — Failing to specify the acceptance level in the test report. Every UT weld test report should clearly state the applied acceptance level (AL2 or AL3). The evaluation level in dB, the recording level in dB, and the reference reflector used. Reports that omit this information are incomplete and non-compliant with ISO 17640 reporting requirements.

How ISO 11666 Relates to Other Major UT Acceptance Standards

For practitioners who work across multiple code environments, here is the orientation table that I share in our UT Level II training:

The important thing to note: ASME and ISO acceptance systems are fundamentally different in their approach. ASME uses a simpler reject/accept binary based primarily on whether the indication exceeds the DAC curve. A DAC-crossing indication is typically rejectable (with some additional evaluation criteria). ISO 11666 uses a more nuanced system in which amplitude and length together determine acceptance. Thus allowing inspectors to accept certain above-DAC indications if their length remains within permissible limits.

This means you cannot substitute one for the other without understanding which is more conservative for a given indication. ASME might reject a short but high-amplitude indication that ISO 11666 AL3 would accept.While certain ASME interpretations might accept a long but moderate-amplitude indication that ISO 11666 AL2 would reject. Know your code, and apply it correctly.

Writing the ISO 11666 UT Test Report

The ISO 17640 reporting requirements (which govern the test report for UT of welds using ISO 11666 acceptance criteria) specify that every compliant test report must include:

• Name of the testing organisation and name of the inspector
• Inspector’s qualification level and certification scheme
• Name of the client and identification of the tested object
• Material specification, dimensions, and condition of the weld
• Testing standard: ISO 17640, testing level specified
• Acceptance standard: ISO 11666:2018, acceptance level applied (AL2 or AL3)
• Reference reflector: type (SDH or FBH), diameter, location in calibration block
• Probe details: type, frequency, angle, size, manufacturer, serial number
• Instrument type and serial number
• Calibration date and reference (instrument must be in calibration)
• Recording level, evaluation level, and acceptance level in dB relative to H0
• Transfer correction applied (value in dB, or statement that correction was less than 2 dB)
• Scanning pattern and coverage achieved
• For each recorded indication: location, depth, measured length, maximum amplitude (relative to H0), assessment (Accepted/Rejected)
• Overall conclusion: Accepted or Rejected
• Date of testing
• Authorised signature — minimum UT Level II per applicable certification scheme

A report that is missing any of these elements is incomplete by the standard’s requirements. For NABL-accredited reports (as issued by Trinity NDT WeldSolutions), additional requirements per ISO/IEC 17025 — including measurement uncertainty statement, NABL logo and accreditation number, unique report reference, and non-modification statement — also apply.

The Bigger Picture — Why Acceptance Standards Matter More Than Many Realise

Let me close with something that goes beyond the technical detail.

I started in NDT in the late 1990s, and early on, a conversation with a senior inspector who had worked on refinery piping for two decades struck me deeply. He said something that stayed with me: “The acceptance criterion is not just a number. It is a statement about what humanity has collectively agreed is safe enough.”

That sounds philosophical for an NDT standard. But think about what is behind ISO 11666:2018. The acceptance levels are not guesses or conservative rule-of-thumb estimates. They are the product of decades of fracture mechanics research — understanding how cracks and other weld discontinuities behave under load, how they grow under cyclic stress, at what size they become critical under the design loading conditions of real structures. Research grounds the ISO 5817 quality levels, which in turn drive the ISO 11666 acceptance levels.

When you apply AL2 and reject a weld with an indication that slightly exceeds the acceptance criteria, you are making a decision that the research says that particular combination of amplitude and length represents a risk that the design did not account for and cannot reliably tolerate. When you accept a weld with a 14 mm indication where the limit is 15 mm, you are making a decision that the research says this particular size, in this material, at this depth, is below the threshold at which fracture mechanics predicts failure at the design stress.

This is why the acceptance criterion matters. It is not negotiable based on convenience or client pressure. Every UT inspector who applies ISO 11666 should understand — not just memorise — the principles behind the numbers.

Our UT Testing and Training Services at Trinity NDT

At Trinity NDT WeldSolutions, we provide NABL ISO/IEC 17025:2017 accredited Ultrasonic Testing services for welds in pressure vessels. Also, piping, structural steel, and aerospace components — to ISO 17640 and ISO 11666, as well as ASME Section V, AWS D1.1, API 1104, and other applicable codes. Trinity NDT issues all UT test reports with NABL accreditation. Wherever they fall within scope, giving your quality system independently verified confidence in the results.

Trinity NDT also conducts UT Level I and Level II certification training—both online (live virtual via Zoom) and offline (in-person at its Peenya, Bangalore facility)—covering ISO 11666, ISO 17640, and ASME Section V acceptance criteria in detail using real production radiographs and UT test records.

If you have a specific question about ISO 11666 application — which acceptance level is appropriate for your application. How to handle a borderline indication, or how to write a compliant UT procedure referencing this standard. I am happy to discuss it. That is exactly the kind of technical consultation that we provide as part of our ASNT Level III NDT consulting service.

WhatsApp: +91 98441 29439 | Email: info@trinityndt.com

About the Author: Ravi Kumar Thammana is the CEO and Co-Founder of Trinity NDT WeldSolutions Pvt. Ltd., Bangalore. He holds ASNT Level III certification in all six NDT methods (UT, RT, MT, PT, VT, ET), International Welding Engineer (IWE) from IIW India, NAS 410 Level III (Aerospace NDT), and Radiological Safety Officer (RSO) from AERB/BARC. Trinity NDT holds NABL ISO/IEC 17025:2017 accreditation (TC-5934) and NADCAP Aerospace Merit accreditation. He blogs at materials-testing.blogspot.com.

The post ISO 11666:2018 — Acceptance Levels for Ultrasonic Testing of Welds: Everything You Need to Know appeared first on Trinity NDT WeldSolutions Private Limited.

There are jobs in this work that go exactly as planned. You set up the equipment, run the procedure, the readings drop, and the component goes out the door. The client is happy, the report is signed, and you move on to the next job. We are about to know an interesting demagnetization case study.

And then there are days when a component gives you a fight.

Today was one of those days — and the component that decided to be stubborn was a steel shaft that arrived at our Peenya laboratory carrying over 10 Gauss of residual magnetism and an absolutely determined resistance to losing it.

This is the story of that shaft, how it got to 10 Gauss, why that is a serious problem for any rotating machine, and what it took to bring it back down below the 3 Gauss threshold that industry standards demand.

First — Why Was This Shaft Magnetised?

The client who brought this shaft to us had previously sent it for Magnetic Particle Inspection (MPI) at another facility. MPI — also called Magnetic Particle Testing (MPT) — is one of the most effective methods for detecting surface and near-surface cracks in ferromagnetic components. During MPI, a strong magnetic field is intentionally induced into the component using either a yoke, a prod, a coil, or a bench-type stationary machine. This magnetisation is what makes the test work — it creates the flux leakage that attracts magnetic particles to crack locations and makes them visible.

The problem is that steel has memory. When a magnetic field is applied and then removed, ferromagnetic materials do not simply return to a neutral state. They retain a portion of the induced magnetic field — what we call the residual magnetism or remnant field. In some steels — particularly high-carbon and alloy steels with high coercivity — this residual field can be surprisingly strong and surprisingly stubborn.

On this particular shaft, the MPI inspection had clearly been performed using a high-magnetisation technique. The resulting residual field measured over 10 Gauss on our calibrated digital Gaussmeter when the shaft arrived at our facility.

Why Does 10 Gauss Matter? Why Not Just Leave It?

This is a question we hear regularly. “It’s invisible. It doesn’t affect how the shaft looks. Why does it matter?”

The answer is: because residual magnetism causes damage in ways that are both subtle and accumulative. Let us walk through exactly what happens when a magnetised shaft enters service.

Bearing damage from arc discharge. In a rotating shaft running in electrical equipment, a residual magnetic field creates a voltage potential that can discharge through the bearing races as a tiny electrical arc — sometimes called Electrical Discharge Machining (EDM) pitting of the bearing. Over time, this pitting destroys bearing surfaces, increases noise and vibration, and eventually causes bearing failure. A shaft with 10 Gauss of residual magnetism in a motor or generator is a bearing damage accelerant.

Chip and swarf attraction in machining. If a magnetised shaft goes into a subsequent machining operation — grinding, turning, or polishing — it attracts metallic chips and swarf directly to the surface being machined. These particles become embedded in the surface or cause scoring. The machined finish is compromised, dimensional tolerances suffer, and the component may need to be scrapped.

Interference with precision instruments. Any precision measuring instrument — a CMM probe, a dial gauge, a digital calliper — that comes close to a strongly magnetised shaft will give false readings or suffer calibration drift. In a quality-controlled manufacturing environment, this is unacceptable.

Other Issues with Residual Magnetism

Welding arc blow. If a magnetised shaft or component is to be welded, residual magnetism causes arc blow — a deflection of the welding arc away from the intended joint. The result is poor fusion, irregular bead geometry, and increased weld defects. For shaft repair or hardfacing welding, demagnetisation before welding is a mandatory first step.

Compass and navigation interference. In marine, aviation, or defence applications, a magnetised component near a compass or navigation instrument can cause heading errors. This is not a theoretical risk — it is a documented failure mode in marine engineering.

For all of these reasons, the standard practice across industries — from automotive and power generation to aerospace and defence — is to specify a maximum residual field of 3 Gauss or less before a component is approved for final assembly or further processing. At 10 Gauss, this shaft was more than three times above the acceptable limit.

The Challenge — Why This Shaft Was Difficult

Image 1: Initial residual field measurement on the shaft — 10+ Gauss. The Gaussmeter probe is positioned at the shaft surface, showing the elevated reading that indicates significant retained magnetism from the previous MPI inspection.

When our Senior Demagnetization Technician first ran the Gaussmeter over the shaft, the reading was immediately concerning — not just for the magnitude, but for the distribution of the field. In a straightforward demagnetisation job, the residual field is fairly uniform across the component surface. You set up the coil, run the procedure, and the readings drop evenly.

This shaft was not straightforward.

The field was distributed asymmetrically across the shaft length — stronger at one end, relatively weaker at the midpoint, and elevated again at the other end. This told an experienced technician something specific: the MPI technique used at the other facility had likely involved multiple separate magnetisation shots at different zones of the shaft, possibly with a prod or yoke technique applied at several points rather than a single coil or through-the-bar technique. Each of those separate magnetisation applications had created its own domain alignment, and those domains were not pointing in the same direction. This is the hardest type of residual magnetism to remove.

Our Senior Technician’s first demagnetisation pass — a standard AC coil technique with slow withdrawal — brought the field down at the shaft midsection but the end zones remained stubbornly high. A second pass produced only marginal improvement. The steel’s coercivity — its resistance to magnetic reversal — was working against us.

This is the point in a demagnetisation job where an inexperienced operator might either declare it “good enough” or escalate unnecessarily. Our technician did neither. He went back to fundamentals.

The Technique That Worked

Without disclosing the specific proprietary parameters of our demagnetisation procedure, here is what the correct technical approach involved for this component:

Step 1 — Reassessment of field distribution. Before running any further demagnetisation attempts, our technician methodically mapped the field across the shaft length at 5 cm intervals, recording the reading at each point. This field map told him exactly where the strongest retention zones were and gave him a basis for assessing whether each subsequent treatment pass was making progress.

Step 2 — Frequency optimisation. The AC demagnetisation coil was set to a frequency and field intensity matched to the shaft’s cross-section diameter and estimated material coercivity — not the default setting, but the calculated optimal parameter for this specific geometry and steel type.

Step 3 — Zone-specific treatment. Rather than treating the entire shaft as a single unit, the technician worked on the high-retention zones separately, using a slower and more controlled coil pass rate in those regions. The field map was re-run after each zone treatment to verify progress.

Step 4 — Final pass — complete shaft. After the zone-specific treatment had brought the problem areas down to a manageable level, a final full-length coil pass was performed to unify the field reduction across the entire shaft length.

Step 5 — Final verification. The Gaussmeter was used to re-survey the entire shaft surface, not just spot-check it. Every measurement point was recorded on the test record.

The result: residual magnetism below 3 Gauss across all measurement points.

The Result — Below 3 Gauss

Image 2: Final residual field measurement after successful demagnetisation — below 3 Gauss. The same shaft, the same Gaussmeter probe, the same measurement location as Image 1. The residual field has been reduced to within the industry-standard acceptance limit, and the shaft is now cleared for assembly, machining, or further processing.

The comparison between Image 1 and Image 2 is the complete story of today’s job. A reading that was well above any acceptable limit, brought back to compliance through methodical technique, the right equipment, and the experience to recognise when a standard approach is not working and adapt.

The client’s shaft left our facility with a formal Demagnetisation Test Record documenting:

• Component description and identification
• Initial residual field readings (mapped at multiple points along the shaft)
• Demagnetisation method, equipment, and parameters used
• Post-demagnetisation residual field readings (verified below 3 Gauss at all points)
• Operator identification and certification
• Date and time of service

That document is the client’s proof — for their quality records, for their client, and for any regulatory or inspection body that might ask — that the demagnetisation was done correctly and was verified.

What the 3 Gauss Specification Means — And Where It Comes From

The 3 Gauss (0.3 mT) maximum residual field requirement is the most widely cited acceptance criterion in industrial demagnetisation. It appears in:

• ASTM E1444 — Standard Practice for Magnetic Particle Testing (the primary MPI standard in the USA and widely followed in India for ASME-coded work)
• AWS D1.1 — Structural Welding Code, which references maximum residual field requirements before welding repairs
• MIL-STD-1949 — Military standard for magnetic particle inspection
• NAS 410 — Aerospace NDT standard (for aerospace-grade components, residual field requirements can be stricter than 3 Gauss)
• Various OEM and end-user specifications for bearing and gear manufacturers

Some specific applications — particularly in precision bearing assemblies, compass-critical components, and aerospace rotating machinery — specify maximum residual fields of 1 Gauss or even below 0.5 Gauss. When clients bring such requirements, our demagnetisation procedure is adjusted accordingly and the verification threshold is tightened to match.

If your component’s specification does not state a residual field limit but you need demagnetisation, our default acceptance criterion is below 3 Gauss — consistent with ASTM E1444. We always record the actual achieved reading so you have the documented evidence, not just a pass/fail statement.

When Is Demagnetisation Required?

Based on the range of jobs we handle at our Peenya facility, these are the most common situations where demagnetisation is needed:

After Magnetic Particle Inspection (MPI/MPT): This is the most frequent reason. Every MPI inspection magnetises the component. If the component is going into service in a bearing, a gear train, an electrical machine, or a high-precision assembly — demagnetise before dispatch.

Before welding or hardfacing: A magnetised component causes arc blow during welding. If you are repairing a shaft, hardfacing a gear, or welding any ferromagnetic component that has been through an MPI inspection, demagnetise before welding.

Before precision machining: Swarf and chip attraction to a magnetised surface is a real problem in precision grinding and turning. Demagnetise before finish machining operations.

Before assembly into precision equipment: Electric motors, generators, turbines, compressors, and gear boxes all contain components that can be affected by residual magnetism in adjacent parts. Demagnetise before final assembly.

Before calibration or use with precision measuring instruments: If a magnetised shaft or component is to be measured with contact gauges or CMM probes, demagnetise first to ensure measurement accuracy.

The Equipment We Use — Why It Matters

Not all demagnetisation equipment is equal, and not all operators are equally skilled in using it.

Our demagnetisation facility at Peenya uses a combination of AC coil demagnetisers sized for different component geometries — from small precision parts to large shafts — and portable yoke-type demagnetisers for in-field and on-site demagnetisation of large structures and weldments.

The verification instrument is a calibrated digital Gaussmeter — not a compass or a simple field indicator, but an instrument that gives precise, quantitative residual field measurements in Gauss or milliTesla, with calibration traceable to national standards. The readings in Image 1 and Image 2 above are real Gaussmeter readings — not estimated, not guessed, not assessed by feel. Measured. Recorded. Reported.

Our demagnetisation technicians are NDT professionals — the same team that performs Magnetic Particle Testing (MPI/MPT) for our clients every day. They understand the physics of magnetism and demagnetisation not just as a procedure to follow, but as a principle they can apply intelligently when a standard approach is not producing the required result. Today proved why that depth of knowledge matters.

A Note on the MPI and Demagnetisation Relationship

One question we hear from clients: “If MPI causes residual magnetism, why do some MPI reports come without a demagnetisation service?”

The answer is: sometimes the residual field left after MPI is already below the 3 Gauss acceptance limit. Particularly when AC yoke technique is used, since AC magnetisation naturally has a partial self-demagnetising. This effect is due to the alternating nature of the field. In those cases, a separate demagnetisation step may not be necessary.

But when high-field DC magnetisation is used. Bench machines with high amperage, or prod techniques. the residual field can be substantial, as this shaft demonstrated. In those cases, a formal demagnetisation step with verified measurement is not optional. It is part of professional MPI service delivery.

At Trinity NDT, our Magnetic Particle Testing (MPI) service routinely includes a residual field check at the conclusion of the inspection. If the field is above the specified limit, our technicians proceed to demagnetisation as part of the job.Not as an afterthought or an add-on.

For components that arrive from other MPI facilities — as this shaft did today. We provide standalone demagnetisation as a specialist service. We measure, treat, verify, and document. The client leaves with both the demagnetised component and the formal test record.

Our Demagnetisation Service — What We Offer

If you have a component that needs demagnetisation. Whether it has just come through MPI, is going into assembly, or is heading for welding repair. Here is what our service includes:

Initial residual field measurement: Full mapping of the component surface before treatment. Not a single spot check, but a systematic survey at multiple points. This gives the baseline reading and identifies zones of concentrated retention.

Treatment: AC coil and/or portable yoke demagnetisation using parameters optimised for the component’s dimensions, geometry, and material. If a standard single-pass treatment is insufficient — as today’s shaft demonstrated — we adapt the approach until the result meets the specification.

Post-treatment verification: Full re-survey of the component surface with the calibrated Gaussmeter. Every measurement point recorded.

Formal Demagnetisation Test Record: Issued with every job. Contains all readings, equipment identification, operator details, treatment parameters, and final acceptance statement. Suitable for inclusion in your Material Data Report (MDR) or quality records.

On-site service available: For large structures, installed equipment, or high-volume production requirements, our technicians can come to your facility with portable demagnetisation and Gaussmeter equipment. We operate from our NDT Labs across Peenya, Bangalore, and across India.

Enquire about our Demagnetisation Service →

Also see: Magnetic Particle Testing (MPI) Services →

The Shaft Leaves. The Learning Stays.

By end of day today, the shaft that arrived carrying 10 Gauss of residual magnetism left our facility in compliance. Below 3 Gauss, verified, documented, and ready for assembly.

The client had been worried. They had an MPI certificate from the inspection facility, but when they measured the shaft on their own floor. The field reading alarmed their assembly engineer. They called us, brought the shaft in, and we sorted it.

This is exactly the kind of problem that a dedicated, experienced demagnetisation team is here to solve. Not every job goes perfectly on the first pass. The steel doesn’t care about your procedure document — it only responds to the physics. Understanding those physics, and having the patience and skill to apply the right technique until the reading drops, is what separates a professional demagnetisation service from one that hands back a still-magnetised component with a rubber stamp.

If your components carry residual magnetism — or if you are simply not sure whether they do — call us or WhatsApp us at +91 98441 29439 and we will advise you on the fastest and most cost-effective path to getting them into compliance.

About Trinity NDT WeldSolutions: Trinity NDT WeldSolutions Pvt. Ltd. is India’s NABL ISO/IEC 17025:2017 accredited and NADCAP Aerospace Merit accredited NDT laboratory at Peenya Industrial Area, Bangalore. We provide Ultrasonic Testing, Magnetic Particle Testing, Liquid Penetrant Testing, Radiographic Testing, Eddy Current Testing, Visual Testing, Positive Material Identification, Hardness Testing, Demagnetisation, Ultrasonic Cleaning, Vapour Degreasing, and advanced NDT (PAUT/TOFD). NDT Level I & II certification training since 2001. 4.8★ Google Rating | 1,200+ reviews | 45+ countries served.

📞 +91 98441 29439 | 📧 info@trinityndt.com | www.trinityndt.com | Peenya Industrial Area, Bangalore 560058

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Basic Standard for QMS

   ISO 9001 -2000

Manufacturing

   ISO 3834, EN 1011, ISO 5817

Personnel

   ISO 9606, EN 287, ISO 14731, ISO 14732

Procedures

   ISO 15607 – 15614

Testing and Inspection Personnel

   ISO 9712, EN 1289

Basis for ISO 3834  series of welding standards

As is well known, weld quality is achieved by sound welding, not by inspection. Inspection, however, provides a check of the reliability of the product, but cannot improve poor quality. Therefore, welding requires continuous control and/or to follow documented procedures. Certifications such as ISO3834 can build a robust quality management systems thus attracting more customers.

Genesis of ISO-3834

A member of the International Union of Technical Associations and Organisations (UTAO), IIW is a part of the International Council for Engineering and Technology (ICET), one of the twelve key formal umbrella organisations associated with UNESCO.

The experts of International Institute of Welding (IIW) have supplied the technical basis of the great majority of welding standards issued by the International Standards Organisation – ISO.

Since 1989, IIW has been recognised by ISO as an International Standardisation Body to prepare the final texts of international welding standards.

Criteria of selection of part of  the standard

• Financial loss
• Loss to human life
• Repair cost
• Loads- static and dynamic

Application of ISO 3834

• Certification of companies in accordance with ISO – 3834 Parts 2, 3 or 4
• Certification of personnel in accordance with ISO 14731

What is ISO 3834?

ISO3834 is an international standard created by welding professionals. ISO 9001 provides the requirements for a quality management system; it does not establish requirements for products. The standard on the other hand, does provide the quality requirements for a welded product.

It specifies requirements relating only to the quality of the welded product. Encourages a proactive process orientated approach to managing and controlling welding   product quality in a workshop or on site. Also, gives a Factory Control System to control activities for the manufacture of the product.

Why adopt ISO 3834 when we have ISO 9001?

ISO 9001 is a comprehensive standard that lays down quality management system requirements for any organisation. However, the standard does not prescribe specific details for “special processes”. Welding is regarded as a ‘special process’. ISO 3834 was developed to identify all factors that could affect the quality of welded product and which need to be controlled at all stages, before, during and after welding.

What are the benefits of specifying the ISO 3834 Standard for the purchaser & supplier?

• More assurance of contract delivery dates
• Greater assurance of the quality of welded products
• Greater reliability and performance of plant
• Reduction in maintenance costs
• Reduction or elimination of third party inspection costs
• More competent suppliers of welded products

What are the benefits of using the ISO 3834 Standard for the manufacturer?

• Less rework
• Jobs completed on time
• Local and international recognition as a competent organisation
• Meet the welding-related requirements of ISO 9001
• More efficient coordination of welding activities
• More pro-active and responsible workforce
• Increased opportunities and capability to bid on jobs
• Cost savings – more efficient technology
• Reduced surveillance audits and inspections by purchasers with significant savings

What are the benefits of using the ISO 3834 Standard for the individual employees?

• Helps to do the job more satisfactorily
• Greater job security
• Higher regard by other people
• Professional recognition
• Satisfied employer and customer
• More rewarding job position
• Develops team spirit

How important are welding personnel?

A key feature of ISO 3834 is the requirement to ensure that people with welding responsibilities are competent to discharge those responsibilities. This is achieved by incorporation of another standard, namely, ISO 14731 “Welding coordination – Tasks and responsibilities”. The specifying of minimum requirements for personnel dealing with welding coordination and welding inspection personnel.

What is the definition of a manufacturer as per standard?

ISO 3834 defines a manufacturer as a ‘person or organization responsible for the welding production’.

The Standard uses this term to describe any such organisation, including manufacturing organisations supplying welding services, either for new products or for repair and maintenance, as well as others where the application of the requirements of ISO 3834 are relevant.

A manufacturer may be involved in manufacture, fabrication, construction, repair or maintenance.

What are the types of manufacturing organisation that ISO 3834 can be applied to?

Fabrication companies

• Construction companies – on-site work

• Repair and maintenance contractors

• Manufacturers of products

• Welding workshops on sites under the same technical and quality management

• Owners of plant with their own workshop(s)

What are the types of other organisation that ISO 3834 can be applied to?

Asset owners without own workshops, both private and government

• Project management companies

• Design companies

• Consultants

• Government agencies

Those which, though not creating welded product themselves, are specifying or requiring such work from others and are thus involved in weld design, contract development, and review of technical requirements and competencies of subcontractors

How many parts does ISO 3834 have?

• ISO 3834: 2005 “Quality requirements for fusion welding of metallic materials” consists of 6 parts:
• ISO 3834-1:2005, Criteria for the selection of the appropriate level of quality requirements
• ISO 3834-2:2005, Comprehensive quality requirements
• ISO 3834-3:2005, Standard quality requirements
• ISO 3834-4:2005, Elementary quality requirements
• ISO 3834-5:2005, Applicable documentation (not full title)
• ISO/TR 3834-6:2007, Guidelines on implementing ISO 3834

How does ISO 3834 link in with ISO 9001?

ISO 3834 does not replace ISO 9001 as a quality management system. However, it contains many attributes that will be important for a welding manufacturer, in both workshops and at field installation sites, seeking ISO 9001 certification. Elements of ISO 9001 should be considered when implementing ISO 3834 quality requirements and seeking ISO 3834 certification. The specific complementary elements of ISO 9001 are detailed in ISO 3834.

What are the main welding requirements covered in ISO 3834 ?

Review of requirements

• Technical review

• Subcontracting

• Welding personnel

– Welders and welding operators, Welding coordination personnel

• Inspection & testing personnel

– Welding Inspection personnel; Non-destructive testing personnel

• Equipment

– Production and testing equipment; Description of equipment; Suitability of equipment; New

equipment; Equipment maintenance

Welding and related activities

– Production planning; Welding procedure specifications (WPS); Qualification of the welding

procedures; Work instructions; Procedures for preparation and control of documents

• Welding Consumables

– Batch testing; Storage and handling

• Storage of parent materials

• Post-weld heat treatment

Inspection and testing

– Inspection & testing before welding; Inspection & testing during welding; Inspection & testing after

welding; Inspection & test status

• Non-conformance and corrective actions

• Calibration and validation of measuring, inspection and testing equipment

• Identification & traceability

• Quality records

Selection of Welding Quality Requirement as per ISO:3834

Comparison of Welding quality requirements with regard to ISO 3834-2, 3834-3  & 3834-4

How do Manufacturers select the Appropriate Part of ISO 3834?

A balanced decision needs to be taken based on the following, related to products & processes:

• The extent and significance of safety-critical products
• The complexity of manufacture
• The range of products manufactured
• The range of different materials used
• The extent to which metallurgical problems may occur
• The extent to which manufacturing imperfections e.g. misalignment, distortion or weld imperfection, affect product performance
• Service condition (Dynamic loading, fatigue, low/high Temperature, corrosion)
• The welding processes adopted, their level of sophistication and automation

Suggested Steps for Implementation of ISO 3834 by an Organisation

• Gap Analysis to identify action areas for  System, training and resources
• Upgradation of System based on above
• Personnel Training for competence
• Assessment of additional Resources if any
• Internal Audit to close NCR’s
• Management Review
• Trial operation to stabilise system
• Application for Certification to Certification Body

Gap Analysis internally by the Organisation against requirements of ISO 3834 & ISO 14731

• ISO 9001 systems if existing or desired and compare with the present system.
• System requirements for applicable part of 3834 (2, 3 or 4) as determined previously and detailed in next three slides.
• Identify each area as per check list for gaps between required/desired level and actual status recorded.
• May take assistance from Consultants or Certifying bodies for this step
• Management corrective action to close the non conformities

To check for Gaps –

Requirements in ISO 3834 & Essential Tasks of  Welding Coordination Personnel in ISO 14731

1.Review of requirements & Technical review to understand parent material specification and welded joint properties, quality and acceptance requirements, etc.

2.Subcontracting Supplier to be treated as extension of manufacturers facility

3.Welding personnel Welders and welding operators, Welding coordination personnel

4.Inspection & testing personnel Welding Inspection personnel; Non-destructive testing personnel

5.Equipment: Production and testing equipment; Description of equipment; Suitability of equipment; New equipment; Equipment maintenance

6.Welding and related activities: Production planning; Welding procedure specifications (WPS); Process Qualification of the welding (WPQR); Work instructions;

7.Welding Consumables: Batch testing; Storage and handling

8.Storage of parent materials

9.Post-weld heat treatment

10. Inspection and NDT testing: Inspection & testing before welding; Inspection & testing during welding; Inspection & testing after welding; Inspection & test status

11.Non-conformance and corrective actions ¬ Learning from experience

12.Calibration and validation of measuring, inspection and testing equipment

13.Identification & traceability

14.Quality records

How important are welding personnel?

A key feature of ISO 3834 is the requirement to ensure that people with welding responsibilities are competent to discharge those responsibilities.

This is achieved by incorporation of another standard, namely, ISO 14731 ‘Welding coordination – Tasks and responsibilities’

The specifying of minimum requirements for personnel dealing with welding coordination and welding inspection personnel

The Human Resource

­Without an appropriate specific technical competence (intended as a combination of knowledge, experience and attitude) no management system can be successful in the manufacturing of any product. ­

A great importance has been entrusted to the Welding Coordinator, who has become the real “key element” around whom all the welding production process works.

ISO 14731 Requirements for Welding Co-ordination Personnel

Welding Co-ordination :

   – Manufacturing operations for all welding and welding related activities

  – The sole responsibility of the manufacturer

  – May be sub-contracted

  – May be carried out by more than one person

Welding Co-ordinator

– Responsible and competent person

– Specified tasks and responsibilities

– Qualified for each task

Welding Inspection

– Is part of welding co-ordination

Role of the Responsible Welding Co-ordinator

The company shall nominate at least one Responsible Welding Co-ordinator ( RWC ). He must be competent to make decisions and sign on behalf of the manufacturer.

The RWC must be authorised with the overall responsibility for monitoring welding activities as well as taking action when welding has not been correctly performed. May also be responsible for the work of other welding co-ordinators in the in the same department / site.

RWC may be to an individuals normal job title eg, Technical Manager, QC Manager, Production Manager etc.

IIW International Diploma Qualifications for Welding Co-ordination Personnel

International Welding Engineer ( IWE )

International Welding Technologist ( IWT )

International Welding Specialist ( IWS )

International Welding Practitioner ( IWP )

International Welding Inspection Personnel (IWIP)

International Welded Structure Designer ( IWSD )

International Welder ( IW ) – Diploma awarded for Specific process and material & at 3 levels

In India, ANB-India of IIW India is authorised to award the above diplomas. Contact IIW India.

ISO 14731 Gradation of Responsible Welding Coordinators

Three different levels of RWC are given. The selection of RWC depends mainly on the variability and technical complexity of the welding procedures required.

How can Trinity NDT Can Help you in ISO3834 certifications?

Center of Welding – Trinity NDT provides comprehensive consulting services for ISO3834 certifications. Being an associate of The Indian Institute of Welding – IIW India, can hand hold organizations in the process of certification.

This includes, quality manual preparation, establishing wps, documentation, QMS implementation, Gap analysis from ISO9001 to ISO3834, NDT Level II personnel certification. Also provide welding coordinator services by our IWE experts. Also an IBR approved Welding & NDT Lab in Bangalore.

Let us know your requirement. Contact Trinity NDT today.

The post ISO3834 Quality Management in Welding Companies appeared first on Trinity NDT WeldSolutions Private Limited.

Penetrant Testing(PT) is also called as Dye Penetrant inspection(DPT) or Fluorescent Inspection FPI Testing in Aerospace is one of the most widely used Non-destructive Evaluation – NDE method. DPT testing is suitable for inspecting steels, aluminium, stainless steels and other materials for surface opened flaws. In brief, this NDT method is suitable for any non-porous material.

Also, a very reliable method for crack testing on Aerospace components and Aircraft structures. However, detectability depends on technique and penetrant sensitivity. For example: When compared to S2 penetrant, S3 will give better sensitivity. Similarly, fluorescent penetrants give better sensitivity when compared to visible penetrants.

Penetrant inspection method is one of the NDT methods for inspection of Welds, Castings, Forgings and Valves. Also, a very reliable method for in-service inspection to find fatigue cracks on automobile, aerospace, oil and gas pipe lines at economical cost.

Of the surface NDT methods, DPT testing is simple in principle and versatile method. To carry the test, the inspector should have proper level of training and certification in Penetrant testing.

Trinity NDT has compete testing labs for penetrant testing up to aerospace standards and procedures. The unique Aerospace NDT Labs at Bangalore India can perform Method A, C and D and sensitivities S2, S3 and S4. In addition, fluorescent and visible penetrant testing also available to offer. The penetrant testing FPI testing labs have accreditation as per ISO17025:2017 from NABL, Delhi, India.

Penetrant – Type, Methods & Sensitivity | Trinity NDT Labs

Even though it is treated as the simplest NDT method, the test results vary greatly in terms of techniques and sensitivity levels employed. Selection of PT technique normally depends on application of component and sensitivity desired. Penetrant inspection techniques are categorized broadly in to

• Type 1 – Fluorescent Penetrants
• Type 2- Visible Penetrants

And, based on method of removal classified as

• Method A – Water Washable
• Method B – Post Emulsifiable, Lipophilic
• Method C – Solvent Removable
• Method D – Post Emulsifiable, Hydrophilic

Also Penetrant Sensitivities are classified as

• ½
• 1
• 2
• 3
• 4

Developer Types

• Dry
• Wet – Aqueous
• Wet – Non Aqueous

Dry Developers are preferred for Aerospace NDT applications. Solvent removable, Wet Aqueous and Non Aqueous developers also available and used based on NDT procedure. That is to say, contact us with your test sensitivity, we have complete range of testing solutions.

As we are serving Aerospace NDT, our laboratory services have all the above types of penetrants and sensitivities to cater to need based inspections.

NABL ISO17025:2017 Accreditation for our FPI Testing Labs

Accreditation of NDT Labs gives additional confidence in test results to customers. Therefore, Our FPI labs are NABL ISO17025 accredited and meets international standards. In addition, the aerospace FPI testing equipment meets ASTM E 1417 and ASTM E 165. One major advantage with Trinity NDT is, all penetrant testing techniques including Fluorescent, Visible penetrants, Water washable, Post Emulsifiable, Solvent removable penetrants up to sensitivity Level 4 are available. So that we are the one stop solutions providing NDT agency trusted by over 500 customers across India.  

Quick Contact us for your requirements on NDT

Stationery FPI equipment | Aerospace NDT Lab in India

Aerospace sector uses altogether high standards of Penetrant materials. Starting from pre cleaning to final cleaning controlling the parameters in each step is vital. Therefore, PT equipment, procedures, training of personnel has clear impact on test results.

We have the best infrastructure to carry FPI testing of aerospace components. The state of art modern Aerospace FPI testing set up is catering to the needs of customers. Our aerospace penetrant testing lab is one of the best facility available in India.

Pre-cleaning procedures include Ultrasonic Cleaning, Alkaline cleaning and solvent cleaning solutions.

Our NDT facility undertakes Dye penetrant testing DPT testing both onsite and off-site. We have expertise in DP testing of Welds, Pressure vessels and boiler components, cross country pipe lines, Castings, Valves, gears, Turbine blades and critical aircraft engine components. Timely calibrations, Daily control checks using TAM/PSM panels ensures the process controls are intact.

Aerospace FPI Testing Agency In Bangalore India

Our Aerospace FPI testing labs are providing services to CEMILAC, Government of India, HAL, L & T Aerospace and many more. Contact us to outsource your NDT Testing to us. We assure to deliver the best to meet your expectations in terms of Timely delivery, professional services at affordable cost.

Know more about Aerospace NDT FPI testing facilities.

Codes, Standards On Liquid Penetrant Testing

Even though there are numerous standards on Penetrant testing such as ASTM E 165 and ASTM E 1417. Also ASME Section V – Non-destructive Examination, API Codes, AWS codes, BS Standards, EN standards provide acceptance criteria. Trinity NDT – Testing Labs uses procedures that meets international standards, codes and customer specifications.

NDT PT Level II Technicians | PT FPI Services

Trinity NDT maintains its Written practice that meets ASNT SNT TC 1A. We engage only Dye penetrant testing / FPI testing Level II technicians. All the DPT testing procedures are duly approved before starting testing by in house ASNT NDT level III. 

NAS410, ASNT NDT Level III Services | Penetrant Inspection

Trinity NDT have in-house Penetrant Testing ASNT Level III. Every NDT procedure is approved by the Level III to meet client needs. We also provide ASNT NDT Level III services such as preparing NDT procedures, Written Practice for personnel certification and layout setting up of penetrant testing facility.

Why do you need to choose Trinity NDT Labs in Bangalore India ?

• We are the best Liquid dye penetrant inspection services provider in Bangalore.
• Modern testing equipments with S2, S3 & S4 sensitivity penetrants. Water washable, post Emulsifiable penetrants for high sensitivity Aerospace NDT FPI testing. Also suitable for components upto 600mm in size.
• UV black light kits for fluorescent inspection
• Liquid penetrant testing technicians with PT Level I, II ASNT SNT-TC-1A and or IS:13805 certified by ISNT. Also have NAS410 Level 2 in Penetrant testing for Aerospace FPI inspections.
• In house NAS410 & ASNT NDT Level III consultants and experts for providing NDT procedure preparation, approval and consultancy services.
• NDT Level III trainers for conducting NDT Level 1, 2 training and certification courses on Liquid dye penetrant testing and other NDT inspection methods. Read more about Liquid Penetrant Testing Personnel Certifications.
• Strong team of NDT Level 2 certified Technicians and inspectors to provide PT and NDT services across India
• Sales and Supply of Dye penetrant inspection (DPT) chemicals kit, penetrants, cleaners, solvents, developers in Peenya Bangalore. If you want to buy DPT chemicals kit, we are the suppliers in Bangalore with ready stock today. Read more about sales of Liquid Penetrant inspection chemicals kit and consumables.

What is the principle of Dye Penetrant testing?

Dye penetrant testing works on principle of capillary action and blotting action (reverse of capillary action). While Capillary action allows penetrant to enter the surface opened flaws, blotting action brings back penetrant from inside of flaws. As capillary action can work in any direction irrespective of gravity forces, therefore cracks of any direction can be easily detected in DPT testing. Earlier the method is called as ‘Oil and whiting method’.

Dye Penetrant inspection | Applications

Penetrant inspection NDT method has many applications. Following a few of them.

• DPT of weld root run to find root flaws before proceeding for next welding layers
• Castings DP testing to find shrinkage at raisers and other areas
• Pipeline and pressure vessel weld joints after final welding
• Leak testing using penetrant testing for gross leaks
• In-service inspection of gears, shafts, valve castings, forging and plates
• Penetrant Inspection after bending to required angle to find cracks
• PT testing of Boiler tubes, pipes, headers and power plant machinery
• FPI testing of turbine blades for aerospace
• Aircraft Structural skin testing using FPI testing

Training Courses | Penetrant testing PT Level 2 and 3

Want To Learn And Get Certified To NDT Level / II after training course on Penetrant Inspection? You hear it right. We would like to share our experience through QA/QC courses organized at our Training Centre in Bangalore India. We offer these NDT courses since 2001 in Hosur and Mysore as well for the industries in these areas.

Trinity Institute of NDT Technology is a training division of Trinity NDT. The institute in India offers world class NDT courses on Penetrant inspection and other NDT testing methods. The training meets written practice and framed to the requirements of ASNT SNT TC 1A. For upcoming Training & certification schedule on PT inspection Level II course visit our Training Calendar page, fee structure, eligibility criteria for the training courses and register for the courses.

Participants from over 40 countries have benefited from our courses. The following are participants from countries whom the institute trained so far in India. Read reviews on Youtube channel

Sale And Supply Of Penetrant Testing Chemicals

Dye Penetrant and fluorescent penetrant chemicals – Solvent removable penetrants, solvent cleaners, developers, accessories and aluminium cracked samples are stocked and supplied for ready use. Items can be hand picked from our office or couriered with prepayment. Quick Contact us for your requirements on PT chemicals sales

Quick Contact us for your requirements on NDT

The post Penetrant Testing Principle, Types, Techniques and Services appeared first on Trinity NDT WeldSolutions Private Limited.

Penetrant Testing(PT) is also called as Dye Penetrant inspection(DPT) or Fluorescent Inspection FPI Testing in Aerospace is one of the most widely used Non-destructive Evaluation – NDE method. DPT testing is suitable for inspecting steels, aluminium, stainless steels and other materials for surface opened flaws. In brief, this NDT method is suitable for any non-porous material.

Also, a very reliable method for crack testing on Aerospace components and Aircraft structures. However, detectability depends on technique and penetrant sensitivity. For example: When compared to S2 penetrant, S3 will give better sensitivity. Similarly, fluorescent penetrants give better sensitivity when compared to visible penetrants.

Penetrant inspection method is one of the NDT methods for inspection of Welds, Castings, Forgings and Valves. Also, a very reliable method for in-service inspection to find fatigue cracks on automobile, aerospace, oil and gas pipe lines at economical cost.

Of the surface NDT methods, DPT testing is simple in principle and versatile method. To carry the test, the inspector should have proper level of training and certification in Penetrant testing.

Trinity NDT has compete testing labs for penetrant testing up to aerospace standards and procedures. The unique Aerospace NDT Labs at Bangalore India can perform Method A, C and D and sensitivities S2, S3 and S4. In addition, fluorescent and visible penetrant testing also available to offer. The penetrant testing FPI testing labs have accreditation as per ISO17025:2017 from NABL, Delhi, India.

Penetrant – Type, Methods & Sensitivity | Trinity NDT Labs

Even though it is treated as the simplest NDT method, the test results vary greatly in terms of techniques and sensitivity levels employed. Selection of PT technique normally depends on application of component and sensitivity desired. Penetrant inspection techniques are categorized broadly in to

• Type 1 – Fluorescent Penetrants
• Type 2- Visible Penetrants

And, based on method of removal classified as

• Method A – Water Washable
• Method B – Post Emulsifiable, Lipophilic
• Method C – Solvent Removable
• Method D – Post Emulsifiable, Hydrophilic

Also Penetrant Sensitivities are classified as

• ½
• 1
• 2
• 3
• 4

Developer Types

• Dry
• Wet – Aqueous
• Wet – Non Aqueous

Dry Developers are preferred for Aerospace NDT applications. Solvent removable, Wet Aqueous and Non Aqueous developers also available and used based on NDT procedure. That is to say, contact us with your test sensitivity, we have complete range of testing solutions.

As we are serving Aerospace NDT, our laboratory services have all the above types of penetrants and sensitivities to cater to need based inspections.

NABL ISO17025:2017 Accreditation for our FPI Testing Labs

Accreditation of NDT Labs gives additional confidence in test results to customers. Therefore, Our FPI labs are NABL ISO17025 accredited and meets international standards. In addition, the aerospace FPI testing equipment meets ASTM E 1417 and ASTM E 165. One major advantage with Trinity NDT is, all penetrant testing techniques including Fluorescent, Visible penetrants, Water washable, Post Emulsifiable, Solvent removable penetrants up to sensitivity Level 4 are available. So that we are the one stop solutions providing NDT agency trusted by over 500 customers across India.  

Quick Contact us for your requirements on NDT

Stationery FPI equipment | Aerospace NDT Lab in India

Aerospace sector uses altogether high standards of Penetrant materials. Starting from pre cleaning to final cleaning controlling the parameters in each step is vital. Therefore, PT equipment, procedures, training of personnel has clear impact on test results.

We have the best infrastructure to carry FPI testing of aerospace components. The state of art modern Aerospace FPI testing set up is catering to the needs of customers. Our aerospace penetrant testing lab is one of the best facility available in India.

Pre-cleaning procedures include Ultrasonic Cleaning, Alkaline cleaning and solvent cleaning solutions.

Our NDT facility undertakes Dye penetrant testing DPT testing both onsite and off-site. We have expertise in DP testing of Welds, Pressure vessels and boiler components, cross country pipe lines, Castings, Valves, gears, Turbine blades and critical aircraft engine components. Timely calibrations, Daily control checks using TAM/PSM panels ensures the process controls are intact.

Aerospace FPI Testing Agency In Bangalore India

Our Aerospace FPI testing labs are providing services to CEMILAC, Government of India, HAL, L & T Aerospace and many more. Contact us to outsource your NDT Testing to us. We assure to deliver the best to meet your expectations in terms of Timely delivery, professional services at affordable cost.

Know more about Aerospace NDT FPI testing facilities.

Codes, Standards On Liquid Penetrant Testing

Even though there are numerous standards on Penetrant testing such as ASTM E 165 and ASTM E 1417. Also ASME Section V – Non-destructive Examination, API Codes, AWS codes, BS Standards, EN standards provide acceptance criteria. Trinity NDT – Testing Labs uses procedures that meets international standards, codes and customer specifications.

NDT PT Level II Technicians | PT FPI Services

Trinity NDT maintains its Written practice that meets ASNT SNT TC 1A. We engage only Dye penetrant testing / FPI testing Level II technicians. All the DPT testing procedures are duly approved before starting testing by in house ASNT NDT level III. 

NAS410, ASNT NDT Level III Services | Penetrant Inspection

Trinity NDT have in-house Penetrant Testing ASNT Level III. Every NDT procedure is approved by the Level III to meet client needs. We also provide ASNT NDT Level III services such as preparing NDT procedures, Written Practice for personnel certification and layout setting up of penetrant testing facility.

Why do you need to choose Trinity NDT Labs in Bangalore India ?

• We are the best Liquid dye penetrant inspection services provider in Bangalore.
• Modern testing equipments with S2, S3 & S4 sensitivity penetrants. Water washable, post Emulsifiable penetrants for high sensitivity Aerospace NDT FPI testing. Also suitable for components upto 600mm in size.
• UV black light kits for fluorescent inspection
• Liquid penetrant testing technicians with PT Level I, II ASNT SNT-TC-1A and or IS:13805 certified by ISNT. Also have NAS410 Level 2 in Penetrant testing for Aerospace FPI inspections.
• In house NAS410 & ASNT NDT Level III consultants and experts for providing NDT procedure preparation, approval and consultancy services.
• NDT Level III trainers for conducting NDT Level 1, 2 training and certification courses on Liquid dye penetrant testing and other NDT inspection methods. Read more about Liquid Penetrant Testing Personnel Certifications.
• Strong team of NDT Level 2 certified Technicians and inspectors to provide PT and NDT services across India
• Sales and Supply of Dye penetrant inspection (DPT) chemicals kit, penetrants, cleaners, solvents, developers in Peenya Bangalore. If you want to buy DPT chemicals kit, we are the suppliers in Bangalore with ready stock today. Read more about sales of Liquid Penetrant inspection chemicals kit and consumables.

What is the principle of Dye Penetrant testing?

Dye penetrant testing works on principle of capillary action and blotting action (reverse of capillary action). While Capillary action allows penetrant to enter the surface opened flaws, blotting action brings back penetrant from inside of flaws. As capillary action can work in any direction irrespective of gravity forces, therefore cracks of any direction can be easily detected in DPT testing. Earlier the method is called as ‘Oil and whiting method’.

Dye Penetrant inspection | Applications

Penetrant inspection NDT method has many applications. Following a few of them.

• DPT of weld root run to find root flaws before proceeding for next welding layers
• Castings DP testing to find shrinkage at raisers and other areas
• Pipeline and pressure vessel weld joints after final welding
• Leak testing using penetrant testing for gross leaks
• In-service inspection of gears, shafts, valve castings, forging and plates
• Penetrant Inspection after bending to required angle to find cracks
• PT testing of Boiler tubes, pipes, headers and power plant machinery
• FPI testing of turbine blades for aerospace
• Aircraft Structural skin testing using FPI testing

Training Courses | Penetrant testing PT Level 2 and 3

Want To Learn And Get Certified To NDT Level / II after training course on Penetrant Inspection? You hear it right. We would like to share our experience through QA/QC courses organized at our Training Centre in Bangalore India. We offer these NDT courses since 2001 in Hosur and Mysore as well for the industries in these areas.

Trinity Institute of NDT Technology is a training division of Trinity NDT. The institute in India offers world class NDT courses on Penetrant inspection and other NDT testing methods. The training meets written practice and framed to the requirements of ASNT SNT TC 1A. For upcoming Training & certification schedule on PT inspection Level II course visit our Training Calendar page, fee structure, eligibility criteria for the training courses and register for the courses.

Participants from over 40 countries have benefited from our courses. The following are participants from countries whom the institute trained so far in India. Read reviews on Youtube channel

Sale And Supply Of Penetrant Testing Chemicals

Dye Penetrant and fluorescent penetrant chemicals – Solvent removable penetrants, solvent cleaners, developers, accessories and aluminium cracked samples are stocked and supplied for ready use. Items can be hand picked from our office or couriered with prepayment. Quick Contact us for your requirements on PT chemicals sales

Quick Contact us for your requirements on NDT

The post Penetrant Testing Principle, Types, Techniques and Services appeared first on Trinity NDT WeldSolutions Private Limited.

Magnetic Particle testing is also known as MPI or MPT is a well accepted NDT method to reveal surface and below surface flaws. Applied for ferro-magnetic metals such as Iron, Nickel and Cobalt alloys. Due to its effectiveness in detecting flaws, industries such as Automobile, Oil and Gas, Processing and Aerospace accepted as a means of verifying quality of components and structures.

How to Start Magnetic particle testing?

Before start of any NDT method a detailed procedure shall be prepared. MPI testing also needs a procedure that outlines, essential and non essential parameters. The MPI procedure shall address all key elements of testing. For instance, MPI techniques, powders, light requirements, medium, current calculations, sequence of testing, equipment to be used, personnel qualification etc.,

Therefore, an MPI testing procedure shall be prepared considering the parameters on site. Procedure shall be prepared by a certified NDT Level II and shall be approved by a NDT Level III in Magnetic Particle testing.

Here are key elements and procedure for MPI testing as per ASTM E709/ASTM E1444

What is the difference between ASTM E709 and ASTM E1444

Both the international standards are issued by The American Society for Testing Materials (ASTM). Both the standards are widely used in every industry involving MPI. ASTM E 709 is a mother standards for many of the worlds country specific standards being used today.

ASTM E709 – A Standard Guide for Magnetic Particle testing, covers in detail about every requirement, recommendation pertaining magnetic particle testing.

ASTM E1444 – A standard practice for Magnetic Particle Testing is specifically applicable for Aerospace NDT applications. This is a replacement for US military standard – MIL-STD-1949. Covers minimum requirements for performing MPI testing. Also recommended to use in conjunction with ASTM E709.

Though both the standards are widely accepted in industry, where stringent requirements are to be followed ASTM E1444 is a better choice. Because it has close acceptance limits, this standard is especially used in Aerospace sector for MPI testing. More specifically this standard covers requirement for aerospace industry.

Scope

It covers the techniques for both dry and wet magnetic particle inspection. Applicable for raw materials and semi-processed materials such as blooms, billets, castings, rolled products, forgings and weld joints. It is also can be used in in-service maintenance inspection of plants and structures.

ASTM E709 is a guide that helps you in preparing MPI procedures, establishing techniques. This can also be used for evaluating and reviewing customer specifications. This standard can be applied for parts of any size, material(ferro) and any shape for any application. Therefore, users of this standard are required to exercise to evaluate specific requirements pertaining to their job and conditions.

Does This Standard Specify Acceptance Criteria?

No. ASTM E709 does not specify any acceptance or rejection criteria. This only covers the procedure for magnetic particle inspection. As this standard is used for variety of applications such as automotive, structural, oil and gas and even for aerospace, it is left to the user to specify the criteria for acceptance or rejection.

Therefore, the contracting parties shall specify acceptance or rejection criteria in the MPI procedure. It may also be cross referenced in place of specifying in procedure. An ASNT Level III or an expert in design shall be consulted for deciding on the criteria. This shall be based on criticality of application, risk associated with failure of the part.

What MPI techniques are used?

1. Dry Powder Technique
2. Wet powder technique

and other techniques which are not much use in industries.

What is the personnel qualification requirement to do MPT testing?

MPI testing inspector should be performed by qualified and certified as per ASNT recommended practice SNT TC 1A or ANSI, CP189 or NAS410(aerospace). The document also gives freedom to specify certification scheme based on agreement between contacting parties such as ISO9712 certifications.

Reference Documents

A number of specifications and standards are listed for the benefit of users. It is good if you can buy there standards from ASTM website for additional knowledge. Also, a standard ASTM E1316 gives definitions related to terminology applicable for Nondestructive testing.

Summary of Magnetic particle Testing

In MPT testing, initially magnetic flux is introduced by a suitable means. This could be using directly passing current techniques such as Head Shot, Prod or Indirect techniques that passes only magnetic field, such as Yoke, Central conductor etc.,

By applying Fleming’s right hand rule we can find the direction of magnetic field if we know the direction of electric current. Once magnetic field is introduced into any ferro magnetic metals, flux lines will be travelling through the materials. If there are any flaws, flux will be distorted and leakage field is created. As we cannot sense leakage flux, a finely powdered ferro-magnetic powder is uniformly sprinkled on the surfaces.

Leakage flux attracts the ferro-magnetic powder thereby bridging the space between the crack/flaw faces. The powder is added with a pigment for suitable viewing. Fluorescent powders are to be used only in darkened room. These powders emits yellowish green light when impinged by Ultraviolet (UV) light in the wavelength range of 320-365nm.

Fluorescent powder absorbs UV light and emit visible light at around 555nm. As Yellowish green light is highly sensitive to human eye, the MPI inspector will be able to locate the indication easily. Non-fluorescent powders are colored with black, red, grey to give contrast with respect to surface.

How to select fluorescent or Non-fluorescent techniques in Magnetic particle testing?

Fluorescent powder technique is suitable for high speed sensitive applications. Non-fluorescent techniques are good for field/site testing conditions where components cannot be moved to a darked area to maintain darkness. Later technique is economical and a cost effective solution at the cost of less sensitivity.

Magnetization Techniques

• Permanent Magnet
• Electromagnetic Yoke
• Head Shot
• Central Conductor
• Cable wrap
• Solenoid
• Coil Shot
• Prod Technique
• What kind flaws can MPI testing detect?

Magnetic particle testing detect flaws located perpendicular to magnetic flux. Flaws located up to 45 degree may also be detected.

How many directions do we need to magnetize?

For effective testing, magnetic field shall be introduced in two mutually perpendicular directions. Inspector shall ensure this while establishing the technique for all surfaces, wherever practicable. The procedure must address techniques to generate the field in various directions.

What is multi-directional magnetization?

Equipment with multi directional magnetization are available. These equipment generate vector field so that the magnetic field rotates almost 360 degree in each shot. Therefore, whatever may be the flaw orientation at one point of time the vector will be perpendicular to the flaw. However, equipment that generate multi directional fields are expensive thus can be used only in critical applications such as aerospace.

Magnetic Field Strength

Magnetic field strength should be sufficient enough to generate leakage flux to detect flaws. Under magnetized components cannot generate the flux enough to detect the defects. Over magnetization causes the field to cause excess in whole of the materials leading to excessive field leakage and heavy accumulation of particles. This leads to shadowing of relevant indications. Because, the contrast is lost flaw identification becomes a challenge.

Therefore, while establishing magnetic field strength it is required to generate just sufficient to detect minimum size of flaw and should not over magnetize to mask indications.

Check how to use ASTM field indicator (Pie Gauge)

Types of Magnetic Particles

Magnetic particles both Dry or Wet based can be used. Fluorescent and non-fluorescent dry or wet particles to be selected based on end user need. Powder concentrates also are specified. Wet particles can be dispersed in water(water based) or carrier oil based (petroleum distillate) that confirms to ASTM E709.

What is meant by indication?

Clustering of powder at a specific area under MPI testing is called Indication. Each indication shall be evaluated for relevance, acceptance or rejection.

How does surface indications looks like?

MPI Indications from surface flaws will be sharp, distinct pattern and tightly held to the surface.

How does subsurface indications looks like?

In MPI testing, subsurface(near surface) indications produce less distinct, fuzzy patterns and powder is loosely held. Indications will be broader than sharp. Just with a small puff of air from mouth can fully or partially eliminate from the surface.

Magnetic Particle testing Equipment Selection

A big challenge for inspectors in MPI testing is selecting right equipment. Numerous equipment and types are available today to choose for testing components and structures.

With the exception of permanent magnetic yoke, all other equipment needs electricity to generate magnetic field.

When do you choose permanent magnetic yoke?

If you want to perform the testing at fire hazard area or where spark can ignite the surrounding or getting electricity at a high altitude is a challenge, such as chimney, permanent magnet is preferred. This equipment does not need electricity. In almost all petroleum refineries, for testing weld joints and parts, permanent magnet is the best option. When all other equipment are prohibited to use, this equipment is the last option.

Before using permanent magnetic yoke, check for calibration and evaluate the strength. It is covered in this post else where.

The post How to Do Magnetic Particle Testing as per ASTM E709 & E1444 appeared first on Trinity NDT WeldSolutions Private Limited.

Magnetic Particle testing is also known as MPI or MPT is a well accepted NDT method to reveal surface and below surface flaws. Applied for ferro-magnetic metals such as Iron, Nickel and Cobalt alloys. Due to its effectiveness in detecting flaws, industries such as Automobile, Oil and Gas, Processing and Aerospace accepted as a means of verifying quality of components and structures.

How to Start Magnetic particle testing?

Before start of any NDT method a detailed procedure shall be prepared. MPI testing also needs a procedure that outlines, essential and non essential parameters. The MPI procedure shall address all key elements of testing. For instance, MPI techniques, powders, light requirements, medium, current calculations, sequence of testing, equipment to be used, personnel qualification etc.,

Therefore, an MPI testing procedure shall be prepared considering the parameters on site. Procedure shall be prepared by a certified NDT Level II and shall be approved by a NDT Level III in Magnetic Particle testing.

Here are key elements and procedure for MPI testing as per ASTM E709/ASTM E1444

What is the difference between ASTM E709 and ASTM E1444

Both the international standards are issued by The American Society for Testing Materials (ASTM). Both the standards are widely used in every industry involving MPI. ASTM E 709 is a mother standards for many of the worlds country specific standards being used today.

ASTM E709 – A Standard Guide for Magnetic Particle testing, covers in detail about every requirement, recommendation pertaining magnetic particle testing.

ASTM E1444 – A standard practice for Magnetic Particle Testing is specifically applicable for Aerospace NDT applications. This is a replacement for US military standard – MIL-STD-1949. Covers minimum requirements for performing MPI testing. Also recommended to use in conjunction with ASTM E709.

Though both the standards are widely accepted in industry, where stringent requirements are to be followed ASTM E1444 is a better choice. Because it has close acceptance limits, this standard is especially used in Aerospace sector for MPI testing. More specifically this standard covers requirement for aerospace industry.

Scope

It covers the techniques for both dry and wet magnetic particle inspection. Applicable for raw materials and semi-processed materials such as blooms, billets, castings, rolled products, forgings and weld joints. It is also can be used in in-service maintenance inspection of plants and structures.

ASTM E709 is a guide that helps you in preparing MPI procedures, establishing techniques. This can also be used for evaluating and reviewing customer specifications. This standard can be applied for parts of any size, material(ferro) and any shape for any application. Therefore, users of this standard are required to exercise to evaluate specific requirements pertaining to their job and conditions.

Does This Standard Specify Acceptance Criteria?

No. ASTM E709 does not specify any acceptance or rejection criteria. This only covers the procedure for magnetic particle inspection. As this standard is used for variety of applications such as automotive, structural, oil and gas and even for aerospace, it is left to the user to specify the criteria for acceptance or rejection.

Therefore, the contracting parties shall specify acceptance or rejection criteria in the MPI procedure. It may also be cross referenced in place of specifying in procedure. An ASNT Level III or an expert in design shall be consulted for deciding on the criteria. This shall be based on criticality of application, risk associated with failure of the part.

What MPI techniques are used?

1. Dry Powder Technique
2. Wet powder technique

and other techniques which are not much use in industries.

What is the personnel qualification requirement to do MPT testing?

MPI testing inspector should be performed by qualified and certified as per ASNT recommended practice SNT TC 1A or ANSI, CP189 or NAS410(aerospace). The document also gives freedom to specify certification scheme based on agreement between contacting parties such as ISO9712 certifications.

Reference Documents

A number of specifications and standards are listed for the benefit of users. It is good if you can buy there standards from ASTM website for additional knowledge. Also, a standard ASTM E1316 gives definitions related to terminology applicable for Nondestructive testing.

Summary of Magnetic particle Testing

In MPT testing, initially magnetic flux is introduced by a suitable means. This could be using directly passing current techniques such as Head Shot, Prod or Indirect techniques that passes only magnetic field, such as Yoke, Central conductor etc.,

By applying Fleming’s right hand rule we can find the direction of magnetic field if we know the direction of electric current. Once magnetic field is introduced into any ferro magnetic metals, flux lines will be travelling through the materials. If there are any flaws, flux will be distorted and leakage field is created. As we cannot sense leakage flux, a finely powdered ferro-magnetic powder is uniformly sprinkled on the surfaces.

Leakage flux attracts the ferro-magnetic powder thereby bridging the space between the crack/flaw faces. The powder is added with a pigment for suitable viewing. Fluorescent powders are to be used only in darkened room. These powders emits yellowish green light when impinged by Ultraviolet (UV) light in the wavelength range of 320-365nm.

Fluorescent powder absorbs UV light and emit visible light at around 555nm. As Yellowish green light is highly sensitive to human eye, the MPI inspector will be able to locate the indication easily. Non-fluorescent powders are colored with black, red, grey to give contrast with respect to surface.

How to select fluorescent or Non-fluorescent techniques in Magnetic particle testing?

Fluorescent powder technique is suitable for high speed sensitive applications. Non-fluorescent techniques are good for field/site testing conditions where components cannot be moved to a darked area to maintain darkness. Later technique is economical and a cost effective solution at the cost of less sensitivity.

Magnetization Techniques

• Permanent Magnet
• Electromagnetic Yoke
• Head Shot
• Central Conductor
• Cable wrap
• Solenoid
• Coil Shot
• Prod Technique
• What kind flaws can MPI testing detect?

Magnetic particle testing detect flaws located perpendicular to magnetic flux. Flaws located up to 45 degree may also be detected.

How many directions do we need to magnetize?

For effective testing, magnetic field shall be introduced in two mutually perpendicular directions. Inspector shall ensure this while establishing the technique for all surfaces, wherever practicable. The procedure must address techniques to generate the field in various directions.

What is multi-directional magnetization?

Equipment with multi directional magnetization are available. These equipment generate vector field so that the magnetic field rotates almost 360 degree in each shot. Therefore, whatever may be the flaw orientation at one point of time the vector will be perpendicular to the flaw. However, equipment that generate multi directional fields are expensive thus can be used only in critical applications such as aerospace.

Magnetic Field Strength

Magnetic field strength should be sufficient enough to generate leakage flux to detect flaws. Under magnetized components cannot generate the flux enough to detect the defects. Over magnetization causes the field to cause excess in whole of the materials leading to excessive field leakage and heavy accumulation of particles. This leads to shadowing of relevant indications. Because, the contrast is lost flaw identification becomes a challenge.

Therefore, while establishing magnetic field strength it is required to generate just sufficient to detect minimum size of flaw and should not over magnetize to mask indications.

Check how to use ASTM field indicator (Pie Gauge)

Types of Magnetic Particles

Magnetic particles both Dry or Wet based can be used. Fluorescent and non-fluorescent dry or wet particles to be selected based on end user need. Powder concentrates also are specified. Wet particles can be dispersed in water(water based) or carrier oil based (petroleum distillate) that confirms to ASTM E709.

What is meant by indication?

Clustering of powder at a specific area under MPI testing is called Indication. Each indication shall be evaluated for relevance, acceptance or rejection.

How does surface indications looks like?

MPI Indications from surface flaws will be sharp, distinct pattern and tightly held to the surface.

How does subsurface indications looks like?

In MPI testing, subsurface(near surface) indications produce less distinct, fuzzy patterns and powder is loosely held. Indications will be broader than sharp. Just with a small puff of air from mouth can fully or partially eliminate from the surface.

Magnetic Particle testing Equipment Selection

A big challenge for inspectors in MPI testing is selecting right equipment. Numerous equipment and types are available today to choose for testing components and structures.

With the exception of permanent magnetic yoke, all other equipment needs electricity to generate magnetic field.

When do you choose permanent magnetic yoke?

If you want to perform the testing at fire hazard area or where spark can ignite the surrounding or getting electricity at a high altitude is a challenge, such as chimney, permanent magnet is preferred. This equipment does not need electricity. In almost all petroleum refineries, for testing weld joints and parts, permanent magnet is the best option. When all other equipment are prohibited to use, this equipment is the last option.

Before using permanent magnetic yoke, check for calibration and evaluate the strength. It is covered in this post else where.

The post How to Do Magnetic Particle Testing as per ASTM E709 & E1444 appeared first on Trinity NDT WeldSolutions Private Limited.

Introduction to NDT

NDT, or Non-Destructive Testing, is a unique technology that involves the use of various techniques to inspect and evaluate the properties of a material, component, or system without causing damage. There are a wide variety of NDT methods, each of which has its own unique set of principles and applications. Some common NDT methods include eddy current testing, acoustic emission testing, ultrasonic testing, magnetic particle inspection, radiographic testing, and visual inspection.

Technicians for NDT Inspection

NDT technicians are trained to use these methods to detect and evaluate defects in materials and structures, ensuring that they meet required specifications and standards. These technicians are often employed in industries such as aerospace, manufacturing, oil and gas, and power generation, as well as in the public sector for infrastructure maintenance.

Tests are performing during various stages of manufacturing such as raw materials, in process and final stages. This will ensure the quality of products is not deviating out of the standard. Besides, NDT is also routinely used for periodic in-services inspection of plants and structures to maintain safety and reliability.

Unlike Destructive testing where certification is not essentials, NDT needs a certified technician either to Level I or Level II. Standards mandates certification of individuals. Level I technicians can do specific testing, calibration and set up of instruments. Level II technicians in addition to Level I duties, can select a technique, do interpretation and evaluation of indications.

How to become NDT Technician?

To become certified as an NDT technician, individuals must complete a certain amount of training and pass exams that demonstrate their proficiency in a specific NDT method or methods. The certifying organizations for NDT technicians are typically professional societies or government agencies that have established standards and guidelines for the training and certification of NDT personnel.

Certifying Institutions, Certification Bodies

One of the most well-known certifying organizations for NDT technicians is the American Society for Nondestructive Testing (ASNT). The ASNT offers a variety of NDT certification programs, including levels I, II, and III. To become certified at Level I, individuals must complete a specific amount of classroom training and pass a written exam. To become certified at Level II, individuals must have practical experience in the specific NDT method they are seeking certification in, as well as pass a written exam. Level III certification is the highest level of NDT certification, and it requires a combination of practical experience and management skills, as well as the successful completion of written (General and Specific) and practical exams.

Other certifying organizations for NDT technicians include the Canadian Society for Nondestructive Testing (CSNDT), the British Institute of Nondestructive Testing (BINDT), and the European Federation for Nondestructive Testing (EFNDT). These organizations offer their own certification programs and exams, which may have slightly different requirements and standards. These organizations are chosen based on end customer needs.

Employer certifications such as ASNT SNT TC 1A are issued by employers based on written practice. Companies can use outside agencies such as Trinity Institute of NDT Technology for training.

Regulatory and Industry Specific Requirements

In addition to professional certification, NDT technicians may also be required to meet certain regulatory or industry-specific requirements. For example, technicians who work in the aviation industry may be required to hold an Airworthiness Certificate, which demonstrates their competency in the use of NDT methods for the inspection and maintenance of aircraft. NAS410 certification falls under this category. It is a mandatory certification if a technician chooses to work on aerospace NDT.

Technicians to work in Boiler pressure vessel code ASME shall meet the provisions in ASME Section V- nondestructive evaluation. Similarly, Radiography technicians (RT) shall take radiation safety course as per the country norms. For example, In India, technicians performing RT shall be certified in Radiation safety from Atomic Energy Regulatory Board (AERB), Mumbai.

Each institution doing radiography shall have a Radiological Safety Officer (RSO) from BARC, Mumbai to ensure safety of operations. This is also known as BARC Level II certification in Radiography testing. Technicians interested in taking RT Level I or Level II can contact AERB/BARC for details.

Conclusion

Overall, NDT certification is an important way for technicians to demonstrate their knowledge and skills in the use of NDT methods, and it is often a requirement for employment in certain industries. By becoming certified, NDT technicians can be confident that they have the knowledge and skills necessary to perform their job duties safely and effectively. Being a technician gives job satisfaction and gives lucrative packages for happy living.

Suggested Further Reading

How to Choose online NDT Courses | Best Mode of NDT learning ? Find more

6 Best NDT courses for Mechanical Engineers

How Long Does NDT Certification last?

How Do You Become NDT Certified?

Which courses are Suitable for Mechanical Engineers? Short term courses

The post What You Need to Know About Becoming an NDT Technician appeared first on Trinity NDT WeldSolutions Private Limited.

Introduction to NDT

NDT, or Non-Destructive Testing, is a unique technology that involves the use of various techniques to inspect and evaluate the properties of a material, component, or system without causing damage. There are a wide variety of NDT methods, each of which has its own unique set of principles and applications. Some common NDT methods include eddy current testing, acoustic emission testing, ultrasonic testing, magnetic particle inspection, radiographic testing, and visual inspection.

Technicians for NDT Inspection

NDT technicians are trained to use these methods to detect and evaluate defects in materials and structures, ensuring that they meet required specifications and standards. These technicians are often employed in industries such as aerospace, manufacturing, oil and gas, and power generation, as well as in the public sector for infrastructure maintenance.

Tests are performing during various stages of manufacturing such as raw materials, in process and final stages. This will ensure the quality of products is not deviating out of the standard. Besides, NDT is also routinely used for periodic in-services inspection of plants and structures to maintain safety and reliability.

Unlike Destructive testing where certification is not essentials, NDT needs a certified technician either to Level I or Level II. Standards mandates certification of individuals. Level I technicians can do specific testing, calibration and set up of instruments. Level II technicians in addition to Level I duties, can select a technique, do interpretation and evaluation of indications.

How to become NDT Technician?

To become certified as an NDT technician, individuals must complete a certain amount of training and pass exams that demonstrate their proficiency in a specific NDT method or methods. The certifying organizations for NDT technicians are typically professional societies or government agencies that have established standards and guidelines for the training and certification of NDT personnel.

Certifying Institutions, Certification Bodies

One of the most well-known certifying organizations for NDT technicians is the American Society for Nondestructive Testing (ASNT). The ASNT offers a variety of NDT certification programs, including levels I, II, and III. To become certified at Level I, individuals must complete a specific amount of classroom training and pass a written exam. To become certified at Level II, individuals must have practical experience in the specific NDT method they are seeking certification in, as well as pass a written exam. Level III certification is the highest level of NDT certification, and it requires a combination of practical experience and management skills, as well as the successful completion of written (General and Specific) and practical exams.

Other certifying organizations for NDT technicians include the Canadian Society for Nondestructive Testing (CSNDT), the British Institute of Nondestructive Testing (BINDT), and the European Federation for Nondestructive Testing (EFNDT). These organizations offer their own certification programs and exams, which may have slightly different requirements and standards. These organizations are chosen based on end customer needs.

Employer certifications such as ASNT SNT TC 1A are issued by employers based on written practice. Companies can use outside agencies such as Trinity Institute of NDT Technology for training.

Regulatory and Industry Specific Requirements

In addition to professional certification, NDT technicians may also be required to meet certain regulatory or industry-specific requirements. For example, technicians who work in the aviation industry may be required to hold an Airworthiness Certificate, which demonstrates their competency in the use of NDT methods for the inspection and maintenance of aircraft. NAS410 certification falls under this category. It is a mandatory certification if a technician chooses to work on aerospace NDT.

Technicians to work in Boiler pressure vessel code ASME shall meet the provisions in ASME Section V- nondestructive evaluation. Similarly, Radiography technicians (RT) shall take radiation safety course as per the country norms. For example, In India, technicians performing RT shall be certified in Radiation safety from Atomic Energy Regulatory Board (AERB), Mumbai.

Each institution doing radiography shall have a Radiological Safety Officer (RSO) from BARC, Mumbai to ensure safety of operations. This is also known as BARC Level II certification in Radiography testing. Technicians interested in taking RT Level I or Level II can contact AERB/BARC for details.

Conclusion

Overall, NDT certification is an important way for technicians to demonstrate their knowledge and skills in the use of NDT methods, and it is often a requirement for employment in certain industries. By becoming certified, NDT technicians can be confident that they have the knowledge and skills necessary to perform their job duties safely and effectively. Being a technician gives job satisfaction and gives lucrative packages for happy living.

Suggested Further Reading

How to Choose online NDT Courses | Best Mode of NDT learning ? Find more

6 Best NDT courses for Mechanical Engineers

How Long Does NDT Certification last?

How Do You Become NDT Certified?

Which courses are Suitable for Mechanical Engineers? Short term courses

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