If you are a quality assurance manager or a company outsourcing NDT, I strongly recommend you ensure that the facility providing your services has not reduced code requirements. You can ensure this by requesting the personnel records of the technician doing the work and verifying them with the applicable code. This is a normal practice and on request the contractor should provide you with the information within an hour. If they do not, you should question their services and perhaps hire a third party ASNT Level III to provide an onsite audit of their facility. Common mistakes found on certification paperwork include not enough training or experience hours. Training facility, and person that provided the training missing. Method or not listed.

The selection of the PT process revolves around selecting the appropriate method of liquid penetrant either: A - Water Washable, B - Post Emulsified Lipophilic, C - Solvent Removable, or D - Post Emulsified Hydrophilic. The key components of selecting a method are determining the geometry of the part and the amount you are considering processing. Method C is also frequently called spot checking because it is most applicable for inspecting a localized spot. Water washable is frequently used for everyday batch processing and post emulsified is usually used on highly critical components. Historically high-sensitivity penetrants only came in post emulsified form. Today you can purchase water washable and any of the other fluorescent methods in Level IV High Sensitivity penetrants.

The selection of developer: Dry, Water Suspendable, Water Soluble, Non-aqueous Wet is another technical part. The key points are that dry is the least sensitive with non-aqueous being the most. If the part that you are inspecting requires high sensitivity, non-aqueous is the preferred method.

Is penetrant the answer for your specific method? It depends on many variables. Keep in mind that nondestructive testing includes many different methods. Below we will list a method and an example of how it can be or is a better method than liquid penetrant.

MT - Magnetic Particle: if the part is ferrous (attractable by a magnet) you can reduce your processing time to 1 min verses 45 min.

ET - Eddy Current: if you are looking for a crack in a specific location on the surface or just below the surface on a conductive material. You can reduce the processing time to 30 seconds, 5 min including instrument set up time verses 45 min.

UT - Ultrasonics: if you are looking for flaws below the surface, not possible with PT.

RT - Radiography: if you want an internal image equal to a photograph of the part. 5 min verses 45 min.

VT - Visual Testing: if you are looking for large flaws or in a specific area with magnification. This could take 1 min versus 45 min.

LT - Leak Testing: if you want to detect container leaks.

IR - Infrared: if you are looking for corrosion on the back side of an aluminum panel.

In conclusion thank you for taking the time to read our article. For any or your nondestructive needs we hope you consider Aqualified in the future. Feel free to e-mail or call me directly with any questions.

Amado Garcia
a.k.a. Glen
8-23-08
ASNT# 125289
NAS-410 Level III PT, MT, ET, UT, RT, VT


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