NDT personnel certification in the USA

The majority of NDT personnel certification in the USA employs the structure provided by Recommended Practice No SNT-TC-1A. It is described as a quality system and will have a written practice, which is based on the Recommended Practice SNT-TC-1A for the training and certification of NDT personnel. Every written practice might be different in a manner that is specific to the employer.

The first edition of SNT-TC-1A was published in 1966. It is important to repeat that the document is not and has never been a standard; it contains guidelines that the employer uses to create a written practice. SNT-TC-1A is a Recommended Practice. It is further made clear that the written practice created must be acceptable not only to the employer but also to the purchaser.

Each edition is a Recommended Practice, not a code, specification or standard. Each edition requires the employer to establish a written practice. SNT-TC-1A 
proposes that the guidelines may be modified by the employer to suit their needs, but the written practice created must always take account of the needs of the purchaser of the NDT services.

In 1976, ASNT introduced its ASNT NDT Level 3 
programme as an independent theory test, which included a basic examination and a method examination, as determined by ASNT themselves. The programme began with a six-month grandfathering programme and was then followed by examinations, which are now available at examination locations around the world.

My experience shows a large discrepancy between different users of SNT-TC-1A and resultant differences in the quality of the inspectors that have been certified through this system. Many of the end-users of the technicians certificated by this process were not satisfied with the quality of the NDT results obtained by them. Many oil & gas producers created their ‘in-house’ practical examinations for ultrasonic thickness measurements.

This led to the development of the Industry Sector Qualification (ISQ) – Oil and Gas, an advanced practical qualification examination created by a coordination between the American Petroleum Institute (API) and ASNT. This would provide the oil & gas industry with NDT personnel who have demonstrated competency in the practical application of a specific technique through hands-on performance demonstration qualification examinations. The programme was originally introduced for ultrasonic thickness measurement. Shear wave testing is now available and will be followed by phased array and time-of-flight diffraction (TOFD) for ASME weld quality.

ASNT Authorized Exam Centers conduct the ISQ exams. A recent assessment of the effectiveness of these exams is shown below.

Summary of results: 1 June 2019 to 1 January 2022.

  • The first-time pass percentage is low at 37%. 

  • The retake pass percentage is slightly higher at 42%.

  • 4% more candidates took the exam with a digital thickness meter versus a flaw detector and had a 6% lower pass rate.

  • The biggest failure category is the mischaracterisation of wall loss versus mid-wall laminations.

  • Candidates struggle to find the minimum thickness of wall loss samples.

  • Candidates are struggling with coated samples.

  • Most candidates seem to perform well on mid and thick samples with wall loss.

  • Low initial pass rates (37%) are indicative of a lack of training and preparation. 

  • Slightly higher retake pass rates (42%) seem to indicate that some additional training is being administered prior to a retake.

  • ASNT sees this as an identified gap in training (signal analysis, familiarity with single and multiple laminations, isolated pitting, etc).

These results reinforce the requirement for third-party examinations. I have observed similar disparities from one employer to the next, where sometimes there is insufficient training, equipment or test samples available to prepare the candidate sufficiently. In addition, the central certification process removes the Level 3 from the process and the possibility of uneven oversight.

I look forward to the complete transition to a central certification process throughout the USA and the rest of the world. 

This ‘Letter from America’ article is solely based on the opinion of the author. 

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