ARCHEM penetration liquids

ARCHEM penetrant liquids for NDT controls

Penetrant liquids are a product used in non-destructive testing of materials; they give the name to the control technique itself.

The examination with penetrant liquids is aimed at ascertaining the existence of discontinuities that emerge on the surface to be examined. Some classes of production processes (heat treatments, surface finishes, welding, etc.) can produce surface defects which are very dangerous since the heaviest stresses are precisely those that act on the surface. The check is mainly carried out on metallic materials, but it can also be performed on materials of other nature, provided they are inert with respect to the products used for the investigation and are not excessively porous. The analysis is based on the penetration of a liquid with certain characteristics of capillarity, viscosity, wettability and density inside a discontinuity emerging on the surface.

After the removal of the excess liquid and the application of a detector (an absorbent liquid usually based on amorphous silica "Developer") every single discontinuity (Crack) is highlighted. The LPI method covers the 1st level of NDT (non-destructive testing) and is often used in a complementary way to other superficial non-destructive techniques (magnetoscopy in particular) and volumetric (ultrasound and radiography).

Type of liquids:

• Solvent (PRE-CLEANER) For cleaning the surfaces to be examined and for removing excess penetrant. Absolutely free from chlorides and sulphides
• Liquid penetrant (PENETRANT RED) With high sensitivity and a high content of colored pigments. Certifiable on request for current regulations. The penetrant is washable with water or removable with the cleaner.
• Developer (WHITE DETECTOR) In a mixture of highly volatile alcohol. To be applied by spray only. Examine immediately after complete drying of the layer. Absolutely free from chlorides and sulphides.

Regulations

• UNI 8374 (1982) "Products for testing with penetrant liquids: classification, characteristics and tests"
• UNI EN 571-1 (1998) "Examination with penetrant liquids: general principles"
• UNI EN ISO 3452-4 "Examination with penetrating liquids: equipment"