Liquid Penetrant Testing (DPT/FPI) Services in Bangalore: NABL-Accredited Lab

Liquid penetrant testing (PT), also called dye penetrant testing (DPT) or fluorescent penetrant inspection (FPI) for the fluorescent method, is a non-destructive method that finds cracks and other flaws open to the surface of a non-porous material. A coloured or fluorescent liquid is drawn into the flaw by capillary action, then drawn back out with a developer so the indication becomes visible in white light or under UV-A light.

Yes. Trinity NDT’s laboratory in Peenya, Bangalore is accredited by NABL to ISO/IEC 17025:2017 for non-destructive testing, and our aerospace division is accredited by NADCAP for fluorescent penetrant inspection (FPI). The accredited scopes, including penetrant type, method and sensitivity level, can be downloaded from our website. Ask us to confirm your specific requirement is within scope.

PT detects flaws that are open to the surface: cracks, seams, laps, cold shuts, porosity, shrinkage and lack of fusion at the surface of welds, castings, forgings and machined parts. It cannot detect any flaw below the surface, so subsurface defects need ultrasonic testing or radiography, and PT on ferromagnetic parts is often combined with magnetic particle testing for slightly subsurface coverage.

PT works on any non-porous material, metallic or non-metallic, including materials that are not magnetic, such as austenitic stainless steel, aluminium, titanium and non-ferrous alloys. It does not work well on rough, porous or absorbent surfaces, such as some as-cast surfaces or powder-metal parts, because they can trap penetrant and cause false or masked indications.

The weld and adjacent base metal are pre-cleaned, penetrant is applied and allowed to dwell, excess penetrant is removed, and developer is applied and given time to draw indications out. Common standards are ASME Section V Article 6 and ISO 3452-1 for the technique, with ISO 23277 giving acceptance levels, and AWS D1.1 or API 1104 for structural and pipeline work.

Yes. On non-magnetic shafts and gears (austenitic stainless steel, aluminium, titanium alloys) PT is the standard surface method, since magnetic particle testing cannot be used. On ferromagnetic shafts, PT is used where magnetising equipment cannot reach or as a confirmatory check. Keyways, fillets, shoulders and threads are examined closely as common fatigue crack locations.

Fluorescent (Type I) penetrant is viewed under UV-A light in a darkened area and gives the highest sensitivity, used on the laboratory bench for aerospace and critical parts. Visible (Type II) red dye penetrant is viewed in ordinary white light and is quicker to use on site, though it is less sensitive to very fine cracks than fluorescent penetrant.

Water washable (Method A) penetrant is rinsed off directly with water and suits large, less critical parts. Solvent removable (Method C) penetrant is wiped off with a solvent-dampened cloth and suits on-site testing of welds and spot checks. Post emulsifiable penetrant (Methods B and D) needs a separate emulsifier before removal, which gives better flaw retention and higher sensitivity for critical work.

Fluorescent penetrants are classified into five sensitivity levels, from Level 1/2 (ultra low) through Level 1 (low), Level 2 (medium), Level 3 (high) to Level 4 (ultra high). Higher sensitivity levels detect finer surface flaws and are typically used for critical aerospace components. Our laboratory holds NABL scope for sensitivity levels S2, S3 and S4.

ASTM E165/E165M is the general-industry practice for penetrant examination of materials, and ASTM E1417/E1417M sets minimum contract requirements commonly used for aerospace and other critical applications, referring to E165 for supporting technical detail. Aerospace work often also cites AMS 2647. Your contract or specification decides which applies.

No. Unlike magnetic particle testing, which can sometimes work through thin coatings, penetrant testing needs a clean, bare surface so the liquid can enter a surface-breaking flaw. Paint, plating, scale, oil and grease must be removed before testing and the part must be dried before penetrant is applied.

It depends on the material. On ferromagnetic steel welds, magnetic particle testing is usually preferred because it also finds slightly subsurface flaws and needs less surface preparation. Penetrant testing is essential for non-magnetic welds such as austenitic stainless steel and aluminium, and is sometimes used alongside magnetic particle testing to confirm a surface indication.

No. Penetrant testing only detects discontinuities that are open to the surface. It cannot find any flaw below the surface, however close. For internal flaws in welds, castings and forgings, ultrasonic testing or radiography is required, and on ferromagnetic parts magnetic particle testing can add slightly subsurface coverage.

Yes. Our Level II inspectors test on site using portable kits with solvent-removable visible dye penetrant, which does not need a darkened area or UV-A lighting. Fluorescent testing needs a dark inspection area and is normally carried out in our laboratory. We mobilise to Bangalore, Hosur and Mysuru, and travel across India for larger projects.

The cost depends on the penetrant type and method, sensitivity level required, part size and quantity, surface condition, the standard and acceptance criteria, whether NABL or NADCAP-scope reporting is needed, lab or on-site testing, and urgency. We quote after reviewing your drawing, standard and quantity so the price reflects the actual scope. Send the details on WhatsApp for a quotation.

We typically reply with a quotation within two hours of receiving complete details on WhatsApp or email. Lab jobs are scheduled as soon as parts and the purchase order arrive, and we confirm the date when we quote. Report timing depends on quantity, part size, standard and the report format required.

Send the drawing or sketch, material and surface finish or coating, dimensions and weight of the largest part, quantity, the standard, specification and acceptance criteria or your PT procedure, whether testing is in the lab or on site, any aerospace or third-party requirement, and your deadline.

The report identifies the part, material and condition, the standard, procedure and acceptance criteria, the penetrant type, method and sensitivity level used, pre-cleaning, dwell time and developing time, and lighting (UV-A intensity for fluorescent testing). It lists each recordable indication by location, type and size, gives the accept or reject evaluation, and carries the inspector’s certification level and Level III approval.

Yes. Our aerospace division is NADCAP-accredited for fluorescent penetrant inspection, with a dedicated stationary FPI line for components up to 600 mm and a 5-ton EOT crane for larger parts. We test to ASTM E1417 and AMS 2647 with in-house NAS 410 Level III approval, and we serve aerospace, defence and general engineering manufacturers.

Yes. We stock and sell dye penetrant inspection chemical kits (penetrants, cleaners and developers) for use at your own workshop, in aerosol cans and 5-litre containers, and we are dealers for Ferrochem, MR Chemicals and Vector-make Zchem and Crackchek products. Kits can be collected from our office in Peenya or couriered anywhere in India. Prices start from Rs 750 plus GST.

Testing is performed by PT Level II inspectors qualified to ASNT SNT-TC-1A and ISO 9712, and to NAS 410 for aerospace work. In-house ASNT NDT Level III and NAS 410 Level III specialists approve the technique, procedure, acceptance criteria and report before release. Inspectors also train at Trinity Institute of NDT Technology.