API 510 Chapter 15

API 510 Chapter 15 – The NDE Requirements of API 510 and API 577

15.1 NDE Requirements of API 510 and API 577 In many ways, the API 510 Body of Knowledge contains a patchwork quilt of NDE requirements. Figure 15.1 shows the situation; ASME V, VIII and IX all contain NDE requirements related to their own new construction focus while API 510, 577 and 572 supplement this with their own requirements related to in-service inspection, and then repair. API 510, remember, retains its position as the ‘override’ code – taking priority over the others wherever conflict exists (and there are a few such areas).

Other sections of this book cover the requirements of ASME V, VIII and IX in some detail. These are by far the longest sections, as you would expect, as they come from a fully blown construction code. API 577, being a Recommended Practice (RP) document rather than a formal code, takes an almost ‘textbook’ approach. It contains an extremely diverse, and in places quite deep, coverage of metallurgy, welding, NDE and almost everything else – in many areas far too detailed to be included in the API exam.

15.2 API 510 NDE requirements

Surprisingly, API 510 itself does not contain much direct information on NDE at all. What little it does contain is fragmented throughout various chapters of the code in snippets, rather than in a separate chapter. This has three main results: . It is more difficult to find, as it is not contained in one place. . The ‘snippet’ form makes it more suitable for closed-book exam questions.

Figure 15.1 The API 510 patchwork of NDE requirements
Figure 15.1 The API 510 patchwork of NDE requirements

These questions tend to owe more to examination convenience rather than the value of inspection knowledge they contain.

In fairness, API 510 does not pretend to be an NDEorientated code. It is happy to concentrate more on what to do with the results of NDE activities, leaving the description of the technique themselves to other related codes such as ASME V.

15.2.1 Links to API 571 and API 577

API 571, covering damage mechanisms, contains a lot of information on the NDE technique. It relates these to their suitability for finding the results of various damage mechanisms. This document contains a lot of technical opinion, which means that it has to be judgemental on which NDE techniques can and can’t find specific damage mechanisms and defects. You may find, therefore, that you do not actually agree with all of it.

Referring back to API 510, Fig. 15.2 shows some specific sections that contain NDE requirements. Some of these are fact and some are API opinion, but all can contain valid API 510 exam questions. Note how they are all fairly thin on detail, consisting mainly of short statements rather than elaborate technical argument or justifications.

Definition 3.1 What is a defect? A defect is an indication that exceeds the applicable acceptance criteria.
Definition 3.2 So what is an


An indication is just something found by NDE – it may be a defect or it may not.
4.2.4 Responsibilities of the inspector It is the inspector’s job to make sure that NDE meets API 510 requirements.
4.2.5 Who actually does the NDE? API 510 calls NDE technicians or operatives examiners.
5.1.2 Where are NDE activities specified? In the inspection plan (see 5.1.2(d)). On-stream inspections Non-intrusive (meaning NDE) examinations can be used in some situations to replace vessel internal examination.
5.7.1 Choice of NDE technique This section (a) to (j) contains multiple value-judgements on which NDE technique is best for finding what – a common source of exam questions. Shear wave operator qualification It is the plant owner/user’s job to specify that shear wave ‘examiners’ need adequate qualification. Thickness measurement methods A, B or C scan UT are suitable for numerous measurement activities. NDE inaccuracies NDE techniques all have measurement inaccuracies. Approval of repairs NDE of repairs must be approved by the inspector. Repairs to stainless steel overlay Base metal is to be checked by UT to detect post-weld cracking.
8.1.7 NDE of repair welds PT/MT should be performed on weld preparations before welding. NDE of repair welds Repairs require RT (or equivalent) as per the original construction code that was used for the new vessel.
8.1.8 Weld inspection of brittle components NDE is required to find cracks and notches.
8.2.1 Re-rating NDE is an acceptable substitute for pressure testing in proving vessel integrity.
Annex B3.2 Inspector recertification NDE experience may be considered as ‘active engagement as an inspector’.

Figure 15.2 Specific NDE requirements of API 510 9th edition

Click Here To Read Next API 510 Exam Chapter 16- The NDE Requirements of ASME V 

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