Guide to Nadcap NDT (Non-Destructive Testing)

Posted by Chris Kielb on Jun 13, 2019 10:58:10 AM


Advance Welding provides comprehensive Nadcap / Aerospace welding and brazing services. We have future plans to offer Nadcap accredited heat treating and NDT (LPT) services. You can learn about Nadcap NDT (Non-Destructive Testing) in this blog.


There are multiple NDT (Non-Destructive Testing) methodologies which can be Nadcap certified. These include LPT (Liquid Penetrant Testing), MPT (Magnetic Particle Testing), UT (Ultrasonic Testing), RT (Radiographic Testing) and ECT (Eddy Current Testing).

Liquid Penetrant Testing: An NDT method which is highly sensitive to small surface flaws and discontinuities. It works by drawing a liquid penetrant into the surface-breaking crack by capillary action and the excess penetrant is then removed. The developer is applied, and penetrant is drawn out to create a surface indication. Is very flexible in terms of shapes and materials and is very cost effective in terms of object size or quantity of items.

Magnetic Particle Testing: An NDT method commonly used for castings, cracks, embrittlement, forging laps, and welds. The process is used for detecting surface and near-surface discontinuities. It works by magnetizing the object with an invisible magnetic field and if a crack is present, it will cause a disruption in the magnetic field. MPI allows inspectors to see the defect and identify it.

Ultrasonic Testing: An NDT method commonly used for hydrogen flakes, inclusions, incomplete fusion, shrinkage cracks, and stringers. This process has the highest depth of penetration to detect subsurface flaws and their location. UT works by using a transducer to emit high frequency sound energy which moves through the metals in wave form. If there is a discontinuity in the material, part of the energy will be reflected back from the flaw’s surface.

Radiographic Testing: An NDT method that can be used on most materials and detect discontinuities on or below the surface. This method uses X-rays produced by and X-ray tube, or gamma rays, produced by a radioactive isotope. Radiation penetrates the weld, or object and onto a photographic film. The object’s internal structure is then deposited onto the film. Cracks would appear as dark areas on the film. This type of testing can provide a permanent film record of weld quality.

Eddy Current Testing: An NDT method which can detect small cracks near or at the surface of the material. This process works by generating an oscillating magnetic field of current flows through a wire soil in the eddy current probe. The current flowing through changes in amplitude or pattern when cracking or defects are encountered.

An important aspect of NADCAP auditing is the ability to test non-destructively. Advance Welding is currently pursuing becoming a Nadcap accredited Non-Destructive Testing laboratory for Liquid Penetrant Testing. Currently, Advance Welding has a captive laboratory that satisfies the need for metallographic evaluation of resistance welds.

Advance Welding has trained Visual Inspectors in house that are qualified to the requirements of multiple industry specifications such as Electric Boat Workmanship Training and AWS D17.1 Visual Weld Inspection.

To learn more about the Nadcap standards, visit our Guide to Nadcap.

Go here to learn about Nadcap Welding and Brazing.

If you have any questions that aren't available in our blog, please feel free to reach out in the Request a Discovery Call form in the upper right!

Topics: Nadcap

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