API · ASME · ISO · NIST · UKAS
Liquid penetrant testing to detect surface-breaking defects in metals and welds. A reliable, cost-effective NDT method for industrial components in Erbil and across Iraq.
Liquid Penetrant Testing (PT), also called dye penetrant, finds discontinuities that are open to the surface on any non-porous material — ferrous or non-ferrous, metal or many non-metals. A coloured or fluorescent penetrant is drawn into the flaw by capillary action, the excess is removed, and a developer draws the trapped penetrant back out to form a visible indication.
We apply both visible (red dye / white developer) and fluorescent systems, selecting sensitivity level, penetrant family and dwell time to suit the material and the smallest defect that must be detected.
The surface is cleaned and dried, penetrant is applied and left to dwell so capillary action pulls it into any surface-breaking flaw. The excess penetrant is carefully removed, then a developer (dry, wet or non-aqueous) is applied to blot the trapped penetrant back to the surface where it bleeds out into a visible indication.
Visible penetrant is read under good white light; fluorescent penetrant is read under ultraviolet (UV-A) light in a darkened area, giving higher sensitivity for fine, tight discontinuities.
PT detects any discontinuity that is open to the surface: fatigue and stress cracks, weld toe and crater cracks, laps, seams, cold shuts and porosity in castings, grinding cracks, and leaks through thin sections. It works equally on aluminium, stainless steel, titanium, nickel alloys, ceramics and plastics.
Because detection depends on the flaw being surface-connected, PT cannot find subsurface defects — but for tight surface cracks it is often more sensitive than magnetic particle on suitable materials.
The consumable set is penetrant, cleaner/remover and developer, applied by spray, dip or brush. Penetrants are classed by removal method — water-washable, solvent-removable or post-emulsifiable — and by sensitivity level, from low to ultra-high for fluorescent systems.
We control dwell time, temperature and the developer film so the process is repeatable, and verify system performance on reference panels or a known-crack test block.
Relevant indications are classified as linear or rounded, measured, and evaluated against the acceptance criteria of the governing code — for example ASME BPVC Section V Article 6 with Section VIII Appendix 8, or ASME B31.3. Non-relevant and false indications are distinguished and recorded.
The PT report states the technique, penetrant type and sensitivity, dwell and developing times, temperature and every relevant indication, with a clear accept/reject result. Personnel are certified to ASNT SNT-TC-1A or ISO 9712.
PT is used on non-ferromagnetic materials — aluminium, austenitic stainless steel, titanium, copper, nickel alloys and non-metals — where magnetic particle cannot work because the part cannot be magnetised. On ferromagnetic steel, MT is often preferred because it can also reveal slightly subsurface defects.
Sensitivity depends on the penetrant system. High-sensitivity fluorescent penetrants read under UV light can reveal very tight cracks a few micrometres wide, provided the flaw is genuinely open to a clean, dry surface. Surface preparation and correct dwell time matter more to the result than the penetrant alone.
Any oil, grease, paint, scale or moisture can block the flaw opening and stop penetrant from entering, producing a false negative. Pre-cleaning and thorough drying are mandatory steps, and the removal stage must clear surface penetrant without washing it back out of the defect — which is why the process is procedure-controlled.
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