Free Ultrasonic Testing AWS D1.1 NDT Procedure for Welds Joints Download

1. Purpose
This Ultrasonic testing procedure is to describe the minimum requirements for methods, techniques and acceptance standards to be used when performing ultrasonic examination of groove weld and heat affected zones. This Ultrasonic testing procedure an be applied to all structural welds made as per AWS D1.1

Note: This is a sample Ultrasonic testing procedure only for education purpose and shall be modified to suit to individual organization. Usually NDT Level 2 will prepare the Ultrasonic testing procedure and shall be approved by ASNT / NAS410 / ISO9712 Level 3 expert.

2. Reference

2.1 AWS D1.1 – Structural welding code

2.2 SNT – TC – 1A

3. Personnel Qualification

Personnel performing nondestructive examination shall be qualified in accordance with the TRINITY NDT procedure “NDE PERSONNEL CERTIFICATION PROGRAM“which meets the requirements of ASNT Recommended practice, SNT-TC-1A(2021) Edition and the more restrictive requirement of previous editions) and other applicable codes.

4.1 Surface Preparation
All surfaces to which a search unit is applied shall be fee of weld spatter, dirt, grease, oil(other than that used as a couplant), paint, and loose scale and shall gave a contour permitting intimate coupling.
4.2 Procedure and standards
This Procedure is to govern the Ultrasonic testing of groove welds and heat-affected zones between the thickness of 5/16 in.(8mm) and 8 in. (200mm) inclusive. These procedure is not to be used for testing tube-to-tube T-, Y-, or K-connections.
4.3 Variations
Variations in testing procedure, equipment, and acceptance standards not included in procedure may be used upon, agreement with the Engineer. Such variations include other thicknesses, weld geometries, transducer
sizes, frequencies, couplant, painted surfaces, testing techniques, etc.

4.4 Piping porosity
To detect possible piping porosity, RT is recommended to supplement UT of electroslag or electrogas welds.

5 Equipment
5.1 Equipment Requirements
The UT instrument shall be the pulse echo type suitable for use with transducers oscillating at frequencies between 1 and 6 MHz. The display shall be an “A” scan rectified video trace.
5.2 Horizontal Linearity
The horizontal linearity of the test instrument shall be qualified over the full sound path distance to be used in testing in conformance with AWS D1.1, 6.30.1. (Within 2% of the Screen width)
5.3 Requirements for Test Instruments
Test instruments shall include internal stabilization so that after warmup, no variation in response greater than ±1dB occurs with a supply voltage change of 15% nominal or, in the case of a battery, throughout
the charge operating life. There shall be an alarm or meter to signal a drop in battery voltage prior to instrument shutoff due to battery exhaustion.
5.4 Calibration of Test Instruments
The test instrument shall have a calibrated gain control(attenuator) adjustable in discrete 1 or 2 dB steps over a range of at least 60dB. The accuracy of the attenuator settings shall be within plus or minus 1 dB. The procedure for qualification shall be as described in 5.9.2.
5.5 Search units
5.5.1 Straight beam (longitudinal Wave) search unit.
Straight beam(longitudinal wave) search unit transducers shall have an active area of not less than 1/2 square inches[323 square millimeters] nor more than 1 square inch [645 square millimeters]. The transducer shall be round or square. Transducer shall be capable of resolving the three reflections as describe in 5.7.1.3).

5.5.2 Angle beam search units
Angle beam search units shall consist of a transducer and an angle wedge. The unit may be comprised of the two separate elements or may be an integral unit.
1) Angles
The search unit shall produce a sound beam in the material being tested within plus or minus 2°of one of the following proper angles : 70°,60°,45°.
2) Frequency
The transducer frequency shall be between 2 and 2.5 MHz, inclusive.
3) Transducer Dimension.
The transducer crystal shall be square or rectangular in shape and may vary from 5/8 in. to 1 in.(15 to 25mm) in width and from 5/8 to 13/16in.(15 to 20mm) in height (see Figure 2). The maximum width to height ratio shall be 1.2 to 1.0, and the minimum width-to-height ratio 1.0 to 1.0.

4) Marking
Each search unit shall be marked to clearly indicate the frequency of the transducer, nominal angle of refraction, and index point. The index point location procedure is described in 5.7.2.1). Figure

5.6 Couplant
A couplant material shall be used between the search unit and the test material. The couplant shall be either glycerin or cellulose gum and water mixture of a suitable consistency. A wetting agent may be added if
needed. Light machine oil may be used for couplant on calibration blocks.
5.7 Equipment Calibration
5.7.1 Longitudinal Mode
1) Distance Calibration The transducer shall be set in position G with Figure 1, (1) The instrument shall be adjusted to procedure indications at 1 in. [25mm on a metric block], 2 in. [50mm on a metric block], 3 in. [75mm on a metric block], 4 in. [100mm on a metric block], etc., on the display.

2) Amplitude
(1) The transducer shall be set in position G. with Figure 1,
(2) The gain shall be adjusted until the maximized indication from first back reflection attains 50 to 75% screen height.
3) Resolution
(1) The transducer shall be set in position F on the Figure 1,
(2) Transducer and instrument shall resolve all three distances.
5.7.2 Shear Wave Mode(Transverse)
1) Index point
The transducer sound entry point (index point) shall be located or checked by the following:
(1) The transducer shall be set in position D on the Figure 1,
(2) The transducer shall be moved until the signal from the radius is maximized. The point on the transducer which aligns with the radius line on the calibration block is the point of sound entry.
2) Angle
The transducer sound path angle shall be checked or determined by one of the following:
(1) The transducer shall be set in position B on IIW block for 40°through 60°, or in position C on IIW block for angles 60°through 70°. (See Figure 1)
(2) For the selected angle, the transducer shall be moved back and forth over the line indicative of the transducer angle unit the signal from the radius is maximized. The sound entry point on the transducer shall be
compared with the angle mark on the calibration block(tolerance ±2°)
3) Distance Calibration
The transducer shall be set in position D with Figure 1. The instrument shall then be adjusted to attain indications at 4 in.[100mm on a metric block] and 8 in. [200mm on a metric block] or 9 in.[225mm on a
metric block] on the display. 4in.[100mm] and 9in.[230mm] on Type 1 block; or 4in.[100mm] and 8in.[200mm] on a Type 2 block.
4) Amplitude or Sensitivity Calibration
The transducer shall be set in position A with Figure 1. The maximized signal shall then be adjusted from the 0.060in.[1.59mm] hole to attain a horizontal reference-line height indication.
5.8 Standard Test Block
The International Institute of welding (IIW) UT Reference blocks, show in Figure 4, shall be the standard used for both distance and sensitivity calibration.

Notes:

1. The dimensional tolerance between all surfaces involved in referencing or calibrating shall be within
   ±.005in.[0.13mm] of detailed dimension.

2. The surface finish of all surfaces to which sound is applied or reflected from shall have a maximum of 125
   Чin.[3 Чm] r.m.s.
3. All material shall be ASTM A36 or acoustically equivalent.
4. All holes shall have a smooth internal finish and shall be drilled 900 to the material surface.
5. Degree inches and identification markings shall be indented into the material surface so that permanent
   orientation can be maintained.
6. Other approved reference blocks with slightly different dimensions or distance calibration slots are
   permissible.
7. These notes apply to all sketches in Figure 4.

5.9 Equipment Qualification
5.9.1 Horizontal Linearity
The horizontal linearity of the test instrument shall be requalified after each 40 hours of instrument use in each of the distance ranges that the instrument will be used.
5.9.2 Gain Control
The instrument’s gain control (attenuator) shall meet the requirements para 5.7 and shall be checked for correct calibration at two months.
5.9.3 Internal Reflections
Maximum internal reflections from each search unit shall be verified at a maximum time interval of 40 hours instrument used.
5.9.4 Calibration of angle beam search units
With the use of an approved calibration block, each angle beam search unit shall be checked after each eight hours of use to determine that the contact face is flat, that the sound entry point is correct, and that the beam angle is within the permitted plus or minus 2° tolerance in accordance with 5.7.2.1) and 5.7.2.2) search units which do not meet these requirements shall be corrected or replaced.
5.10 Calibration for Testing
5.10.1 Position of Reject Control
All calibrations and tests shall be made with the reject control turned off. Use of the reject control may alter the amplitude linearity of the instrument and invalidate test result.

5.10.2 Technique
Calibration for sensitivity and horizontal sweep (distance) shall be made by the ultrasonic operator just prior to and at the location of testing of each weld.
5.10.3 Recalibration
Recalibration shall be made after a change of operators, each 30 minute maximum time interval, or when the electrical circuitry is disturbed in any way which includes the following :
1) Transducer change
2) Battery change
3) Electrical outlet change
4) Coaxial cable change
5) Power outage (failure)
5.10.4 Straight beam Testing of Base metal
Calibration for straight beam testing of base metal shall be made with the search unit applied to Face A of the base metal and performed as follows:
1) Sweep
The horizontal sweep shall be adjusted for distance calibration to present the equivalent of at least two plate thicknesses on the display.
2) Sensitivity
The sensitivity shall be adjusted at a location free of indications so that the first back reflection from the far side of the plate will be 50% to 75% of full screen height.
5.10.5 Calibration for Angle beam testing
Calibration for angle beam testing shall be performed as follows:
1) Horizontal sweep
The horizontal sweep shall be adjusted to represent the actual sound path distance by using IIW block. The distance calibration shall be made using either the 5in.[125mm] scale or 10 in. [250mm] scale on the display,
whichever is appropriate. If, however, the joint configuration or thickness prevents full examination of the weld at either of these settings, the distance calibration shall be made using 15 or 20 in.[400 mm or 500mm] scale
as required.

6. Ultrasonic testing Procedure for Welds as per AWS D1.1
   6.1 “X” line
   An “X” line for flaw location shall be marked on the test face of the weldment in a direction parallel to the weld axis. The location distance perpendicular to the weld axis is based on the dimensional figures on the detail drawing and usually falls on the centerline of the butt joint welds, and always falls on the near face of the connecting member of T and corner joint welds (the face opposite Face C).
   6.2 “Y” Line
   A “Y” accompanied with a weld identification number shall be clearly marked on the base metal adjacent to the weld that is subject to UT. This marking is used for the following purposes:
   6.2.1 Weld identification
   6.2.2 Identification of Face A
   6.2.3 Distance measurements and direction (+ or -) from the X line
   6.2.4 Location measurement from weld ends or edges.
   6.3 Extend of Testing
   The entire base metal through which ultrasound must travel to test the weld shall be tested for laminar reflectors using a straight beam search unit conforming to the requirements with 5.5.1 and calibrated in
   accordance with 5.10.4. If any area of base metal exhibits total loss of back reflection or an indication equal to or greater than the original back reflection height is located in a position that will interfere with the normal weld scanning procedure, its size, location, and depth from the A face shall be determined and reported on the ultrasonic test report and an alternate weld scanning procedure shall be used.
   6.4 Inaccessibility
   If part of a weld is inaccessible to testing in accordance with the requirements of Table A due to laminar content recorded in accordance with 6.3 the testing shall be conducted using one or more of the following alternate procedures as necessary to attain full weld coverage:

6.4.1 Weld surface(s) shall be ground flush.

6.4.2 Testing from Faces A and B shall be performed.

6.4.3 Other search unit angles shall be used.

6.5 Testing of welds Welds shall be tested using an angle beam search unit conforming to the requirements of 5.5.2 with the instrument calibrated in conformance with5.10.5 using the angle as shown in Table A. Following calibration and during testing, the only instrument adjustment permitted is the sensitivity level adjustment with the calibrated gain control(attenuator). The reject(clipping or suppression) control shall be turned off.Sensitivity shall be increased form the reference level for weld scanning in accordance with Table B or C.

6.6 Scanning The testing angle and scanning procedure shall be in accordance with that shown in Table A.

Notes:

1. Where possible, all examinations shall be made from Face A and in Leg 1, unless otherwise specified in
   this Table.
2. Root areas of single groove weld joints which have backing nor requiring removal by contract, shall be
   tested in Leg 1, where possible, with Face A being that opposite the backing.(Grinding of the weld face or
   testing from additional weld faces may be necessary to permit complete scanning of the weld root.)
3. Examination in Leg II or III shall be made only to satisfy provisions of this table or when necessary to
   test weld areas made inaccessible by an unground weld surface, or interference with other portions of the
   weldment, or to meet the requirements of 6.2.
4. A maximum of Leg III shall be used only where thickness or geometry prevents scanning of complete weld
   areas and heat affected zones in Leg I or Leg II.
5. On tension welds in cyclically loaded structures, the top quarter of thickness shall be tested with the
   final leg of sound progressing from Face B toward Face A, the bottom quarter of thickness shall be tested
   with the final leg of sound progressing from Face A toward Face B; i.e., the top quarter of thickness shall
   be tested either from Face A in Leg II or from Face B in Leg I at the contractor’s option, unless otherwise
   specified in the contract documents.
6. Face A for both connected members shall be in the same plane.

Legend:
X – Check from Face “C”
G – Grind weld face flush.
O – Not required.
A Face – the face of the material from which the initial scanning is done(on T-and corner joints, follow above
sketches).
B Face – opposite the “A”face (same plate).
C Face – the face opposite the weld on the connecting member or a T- or corner joint.

• – Required only where display reference height indication of discontinuity is noted at the weld metal-base
  metal interface while searching at scanning level with primary procedures selected from first column.
  ** – Use 15in.[400mm] or 20 in.[500m] screen distance calibration.
  P – Pitch and catch shall be conducted for further discontinuity evaluation in only the middle half of the
  material thickness with only 45˚ or 70˚ transducers of equal specification, both facing the weld.
  (Transducers must be held in a fixture to control positioning – see sketch.) Amplitude calibration for
  pitch and catch is normally made by calibrating a single search unit. When switching to dual search units
  for pitch and catch inspection, there should be assurance that this calibration does not change as a
  result of instrument variables.
  F – Weld metal-base metal interface indications shall be further evaluated with either 70˚, 60˚, or 45˚
  transducer-whichever sound path is nearest to being perpendicular to the suspected fusion surface.

6.7 Butt joint
All butt welds shall be tested from each side of the weld axis. Corner and T-joint welds shall be primarily tested from one side of the weld axis only. All welds shall be tested using the applicable scanning pattern or patterns shown in Figure 5. as necessary to detect both longitudinal and transverse flaws. It is intended that, as a minimum, all welds be tested by passing sound through the entire volume of the weld and the heat-affected zone in two crossing directions, wherever practical.
6.8 Maximum Indication
When a discontinuity indication appears on the screen, the maximum attainable indication from the discontinuity shall be adjusted to produce a horizontal reference level trace deflection on the display. This
adjustment shall be made with the calibrated gain control(attenuator), and the instrument reading in decibels shall be used as the “Indication Level, a”, for calculating the “Indication Rating, d,” as shown on the test report.
6.9 Attenuation Factor
The “Attenuation Factor, c” on the test report is attained by subtracting
1 in. [25mm] from the sound path distance and multiplying the remainder by 2. This factor shall be rounded out to the nearest dB value. Fractional values less than 1/2 dB shall be reduced to the lower dB level and those of 1/2dB or greater increased to the higher level.
6.10 Indication Rating
The “Indication Rating, d” in the UT Report, represents the algebraic difference in decibels between the Indication Level and the Reference Level with correction for attenuation as indicated in the following
expressions:

Instruments with gain in dB:
a – b – c = d
Instruments with attenuation in dB:
b – a – c = d
6.11 Straight – beam (longitudinal) Testing
The size of lamellar discontinuities is not always easily determined, especially those that are smaller than the transducer size. When the discontinuity is larger than the transducer, a full loss of back reflection will occur and a 6 dB loss of amplitude and measurement to the centerline of the transducer is usually reliable for determining flaw edges. However, the approximate size evaluation of those reflectors, which are smaller than the transducer, must be made by beginning outside of the discontinuity with equipment calibrated in accordance with 5.10.4
and moving the transducer toward the area of discontinuity until an indication on the display begins to form. The leading edge of the search unit at this point is indicative of the edge of the discontinuity.
6.12 Angle – beam (shear) Testing
The length of such indication shall be determined by measuring the distance between the transducer centerline locations where the indication rating amplitude drops 50% (6dB) below the rating for the applicable flaw
classification. This length shall be recorded under “discontinuity length” on the test report.

6.13 Scanning Pattern
6.13.1 Longitudinal Discontinuities
1) Scanning Movement A : Rotation angle a = 10°
2) Scanning Movement B : Scanning distance b shall be such that the section of weld being tested is covered.
3) Scanning Movement C : Progression distance c shall be approximately one-half the transducer width.
Note : movements A, B, and C are combined into one scanning pattern.

6.13.2 Transverse Discontinuities
1) Ground welds
Scanning pattern D is to be used when welds are ground flush.
2) Underground welds
Scanning pattern E is to be used when the weld reinforcement is not ground
flush. Scanning angle e = 15°max.
Note : The scanning pattern is to be such that the full weld section is covered.
6.14 Electroslag or Electrogas welds (Additional scanning Pattern) Scanning pattern
E search unit rotation angle between 45°and 60°
Note : The scanning pattern shall be such that the full weld section is covered.

7. Evaluation & Acceptance Criteria
   7.1 Statically Loaded nontubular connections)
   The acceptance criteria for welds subject to UT in addition to visual inspection shall meet the requirements of Table B.
   For complete joint penetration web-to-flange welds, acceptance of discontinuities detected by scanning movements other than scanning pattern ‘E’ (see para.6.13.2.2) may be based on weld thickness equal to
   the actual web thickness plus 1 in. [25mm]. Discontinuities detected by scanning pattern ‘E’ shall be evaluated to the criteria of Table B for the actual web thickness. When complete joint penetration web-to-flange
   welds are subject to calculated tensile stress normal to the weld, they should be so designated on the design drawing and shall conform to the requirements of Table B Ultrasonically tested welds are evaluated on the
   basis of a discontinuity reflecting ultrasound in proportion to its effect on the integrity of the weld. Indications of discontinuities that remain on the display as the search unit is moved towards and away from the discontinuity (scanning movement “b”) may be indicative of planar discontinuities with significant through-throat dimension. Since the major reflecting surface of the most critical discontinuities is oriented

a minimum of 20°(for a 70° search unit) to 45°(for a 45° search unit) from perpendicular to the sound beam, amplitude evaluation(㏈ rating)does not permit reliable disposition. When indications exhibiting these planar
characteristics are present at scanning sensitivity, a more detailed evaluation of the discontinuity by other means shall be required (e.g., alternate UT techniques, RT, grinding or gouging for visual inspection, etc.).
7.2 Cyclically Loaded nontubular connections
The acceptance criteria for welds subject to UT in addition to visual inspection shall meet the following requirements :
7.2.1 Welds subject to tensile stress under any condition of loading shall conform to the requirements of Table C.
7.2.2 Weld subject to compressive stress shall conform to the requirements of Table B.
1) Indications
Ultrasonically tested welds are evaluated on the basis of a discontinuity reflecting ultrasound in proportion to its effect on the integrity of the weld. Indications of discontinuities that remain on the display as the search
unit is moved towards and away from the discontinuity(scanning movement “b”) may be indicative of planar discontinuities with significant through throat dimension. As the orientation of such discontinuities, relative to the sound beam, deviates from the perpendicular,㏈ ratings which do not permit direct, reliable evaluation of the welded joint integrity may result. When indications that exhibit these planar characteristics are present at scanning sensitivity, a more detailed evaluation of the discontinuity by other means may be required(e.g., alternate UT techniques, RT, grinding or gouging for visual inspection, etc.).
7.2.3 Scanning
Complete joint penetration web-to-flange welds shall conform to the requirements of Table B and acceptance for discontinuities detected by scanning movements other than scanning pattern “E”(see para.6.13.2.2)) may
be based on a weld thickness equal to the actual web thickness plus 1in.[25mm]. Discontinuities detected by scanning pattern “E” shall be evaluated to the criteria of Table C for the actual web thickness. When such
web-to-flange welds are subject to calculated tensile stress normal to the weld, they shall be so designated on design drawings and shall conform to the requirements of Table C.

Notes :

1. Class B and C discontinuities shall be separated by at least 2L, L being the length of the longer discontinuity,
   except that when two or more such discontinuities are not separated by at least 2L, but the combined length of
   discontinuities and their separation distance is equal to or less than the maximum allowable length under the
   provisions of Class B or C, the discontinuity shall be considered a single acceptable discontinuity.
2. Class B and C discontinuities shall not begin at a distance less than 2L from weld ends carrying primary tensile
   stress, L being the discontinuity length.
3. Discontinuities detected at “scanning level” in the root face area of complete joint penetration double groove
   weld joints shall be evaluated using an indicating rating 4dB more sensitive than described in 6.10 when such
   welds are designated as “tension welds” on the drawing(subtract 4dB from the indication rating “d”.
4. Electroslag or electrogas weld: discontinuities detected at “scanning level” which exceed 2in.(51mm) in length
   shall be suspected as being piping porosity and shall be further evaluated with radiography.
5. For indications that remain on the display as the search unit is moved, refer to 7.1.

Repair Requirements

Repair shall be examined by the same procedure used for detection of the discontinuities. Acceptability of repairs shall be determined by the same acceptance standards after doing Ultrasonic testing procedure as per AWS D1.1.

9. Reports and Records
   9.1 Examination of Reports
   A report of the examinations shall be made. the report shall include a record indication the weld(s) or volume examined (this may be marked-up sketched),the location of each recorded reflector, and the identification
   of the operator who carried out each examination or part thereof as detailed 9.2
   9.2 Examination Records For each ultrasonic examination, the following information should be identified and recorded.
   1) Procedure ;
   2) Ultrasonic examination system (equipment) ;
   3) NDT Examination personnel identity and level ;
   4) Calibration sheet identity ;
   5) Identification and location of weld or volume scanned ;
   6) Surface from which examination is conducted ;
   7) Map or record of indications detected or areas clear ;
   8) Date and time examinations were performed ;
   9) Couplant ;
   10) Basic calibration block identification ;
   11) Surface condition ;
   12) Frequency ;
   13) Special equipment ;
   9.3 Evaluation Record
   Records of any evaluations of indications shall be maintained and documented as required by the referencing Code section.

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