API Releases New QUSE-Phased Array Qualification Exam

By John Nyholt, NDT Subject Matter Expert at John Nyholt Consulting, LLC. August 22, 2017

The American Petroleum Institutes's (API) Subcommittee for Inspection and Integrity Management (SCIIM) and the API NDT Task Force recognize the need to maintain the high quality of inspection data. The need for accurate UT angle beam data has become increasingly important for fitness-for-service (FFS) applications and risk-based inspection (RBI). The availability of high quality UT data is often the cornerstone for FFS and RBI decisions. The SCIIM also believes that it is in the industry’s best interest for API to implement a program that assures the highest accuracy possible in ultrasonic flaw sizing

As such, the SCIIM has initiated a Qualification of Ultrasonic crack Sizing Examiners that use ultrasonic Phased Array methods (QUSE-PA). The API pressure vessel and piping inspection codes (API 510 and 570) require UT shear wave examiners that have passed a performance demonstration. To date, the API ultrasonic examiner certification program has provided ultrasonic flaw detection and characterization exams for conventional UT methods (QUTE) and the phased array methods (QUPA). Ultrasonic crack sizing qualification testing has been limited to conventional methods under the QUSE exam. The new QUSE-PA exam brings the API QUSE exam program up to date with current ultrasonic crack sizing technology. Both the QUSE and the QUSE-PA exams will continue to be offered as conventional UT crack sizing techniques continue to be used in the industry.

Ultrasonic crack sizing makes up relatively low percentage of NDT services. Subsequently, many ultrasonic shear wave examiners do not achieve practical field experience after their formal training. The QUSE exam is a practical exam on 16 real world crack specimens, the historic QUSE pass rate over the past several years has been 20-25% and there are only about 65 QUSE certified technicians to date. This can be considered a shortage when compared to the roughly 480 QUTE and 190 QUPA certified examiners. 

The QUSE-PA exam is expected to increase the number of API qualified UT crack sizing examiners. Of the 20 UT Level II and Level III examiners that took part in QUSE-PA beta test, 10 had passed for an initial pass rate of 50%. Higher pass rates are possible for UT technicians that attend 2-3 days of additional guided practice on real crack samples prior to taking the exam. Where Ultrasonic Phased Array courses do a good job of teaching UT theory, equipment and usage, application specific courses or workshops for flaw sizing and other practical applications are recommended in order to develop specific UT examiner skill sets.   

The QUSE-PA exam uses the prior QUSE test specimens, exam protocols and grading criteria.  A few exceptions include new UT-PA crack sizing procedure, UT-Phased Array protocols and the necessary form editing. There are 16 carbon real crack specimens. All of the specimens contain opposite side cracks at the weld root. Half the specimens are 0.375” (9.5 mm) thick and half are 1.00 (25.4 mm) thick. Half of the specimens have their weld crowns in place and half have their weld crowns ground flush with the base metal.

It should be noted that the QUSE and QUSE-PA performance demonstration exams test the examiner’s skills at sizing opposite side cracks. They do not test the examiner’s ability to size same side cracking. The exams are also limited to carbon steel with relatively clean welds. The examiner is not tested on his/her ability to differentiate between original weld flaws and in-service damage such as cracking.

The API SCI recommends that petrochemical owner/operators adopt the API QUSE-PA certificate holder as equivalent to the current QUSE (or equivalent qualification exam program) while using ultrasonic phased array methods.

For more information and registration forms for the API QUSE-PA exam, please visit:

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