Description

Liquid penetrant testing is a non-destructive method used to detect surface breaking defects in any nonporous material. Liquid penetrant is applied to the surface and is drawn into defects by capillary action. Once a preset dwell time has passed, excess penetrant is removed and developer applied to draw out penetrant from defects. Visual inspection is then performed. Visible and Fluorescent Liquid Penetrant Examinations are Non-Destructive methods of revealing discontinuities that are open to the surfaces of solid and essentially non-porous materials, ferrous or non-ferrous.
  • Strong dye sprayed onto surface drawn into cracks and pores by capillary action
  • Surplus is wiped off
  • Developer (e.g. chalk powder suspension) sprayed on to reveal defects
  • Dye can be UV active so viewing under UV illumination reveals cracks

Applications
  • Grinding cracks
  • Heat affect zone cracks
  • Poor weld penetration
  • Heat treatment cracks
  • Fatigue cracks
  • Hydrogen cracks
  • Inclusions
  • Laminations
  • Micro shrinkage
  • Gas porosity
  • Hot tears
  • Cold shuts
  • Stress corrosion cracks
  • Intergranular corrosion

Standards
ASTM E165-02 Standard Test Method for Liquid Penetrant Examination
ASTM E1208-99 Standard Test Method for Fluorescent Liquid Penetrant Examination Using the Lipophilic Post-Emulsification Process
ASTM E1209-99 Standard Test Method for Fluorescent Liquid Penetrant Examination Using the Water-Washable Process
ASTM E1219-99 Standard Test Method for Fluorescent Liquid Penetrant Examination Using the Solvent-Removable Process
ASTM E1316-02a Standard Terminology for Nondestructive Examinations
ASTM E-1418 Test Method for Visible Penetrant Examination Using the Water-Washable Process"
ASTM E1417-99 Standard Practice for Liquid Penetrant Examination

These specifications can be used on their own, but they do have some limitations. Such as: there are no requirements for the approval of penetrant materials, no requirements of in-use testing of materials, and the specification can only be used for the one type, and method of penetrant processing. ASTM E-1209 can only be used for Fluorescent Water-Washable Processing. If the requirement for examination is that the part must be inspected with a Fluorescent Water-Washable material, then ASTM E-1209 could be used. One very important thing to remember is that there are no quality requirements for the penetrant materials, and quality control for the use of these materials. In all cases the requirements for light, meters, gauges, ovens, penetrant materials and in-use material testing will be specified in ASTM E-1417. ASTM E-1417 is the specification that is referenced the most, since it covers all the methods, forms, types of penetrant materials and the quality control requirements used in penetrant processing.

Another specification that is addressed in the Aerospace Overhaul Sector is AMS 2647 "Fluorescent Penetrant Inspection Aircraft and Engine Component Maintenance". This specification is written for the overhaul of aircraft engine parts. This specification can be used for processing aircraft engine parts and uses the same penetrant material qualification specification (AMS 2644) as ASTM E-1417. However, AMS 2647 should only be used for processing aircraft engine parts and not as a general penetrant processing specification.

The general processing specification for liquid penetrants should be ASTM E-1417. This specification uses supporting specifications (like ASTM E-165 "Standard Test Method for Liquid Penetrant Examination"), for processing parts. ASTM E-165 is a guideline for penetrant processing and should only be used as a supporting document to ASTM E-1417. All the specifications that are listed in ASTM E-1417 are listed to provide additional information and support the requirements of ASTM E-1417.

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