|This article is part 2 of a 2-part series.|
|Part 1 | Part 2|
According to the National Board Inspection Code (NBIC), Part 31, paragraph 1.2(a): “When the standard governing the original construction is the ASME Code,…, repairs and alterations to pressure-retaining items shall conform, insofar as possible, to the section and edition of the ASME Code most applicable to the work planned.” NBIC’s interpretation 95-1929 is more specific:
“Question: When the NBIC references ‘the original code of construction’, is it required to use the edition and addenda of that code as used for construction? Answer: No. The term ‘original code of construction’ refers to the document itself, not the edition/addenda of the document. Repairs and alterations may be performed to the edition/addenda used for the original construction or later edition/addenda most applicable to the work”.
But, recommended practice in API RP 5724, paragraph 4.6 says: “A refinery or petrochemical facility inspector should be familiar not only with the latest editions of codes but also with previous editions of the codes and with other specifications under which any vessels they inspect were built”. And finally, if a Fitness-For-Service (FFS) assessment is required, according to API 579-1/ASME FFS-15, paragraph 1.7.2 agrees with API RP 572’s opinion by saying:
“The edition of the codes, standards, and recommended practices used in the FFS Assessment shall be either the latest edition, the edition used for the design and fabrication of the component, or a combination thereof. The engineer responsible for the assessment shall determine the edition(s) to be used.”
In other words, if you are performing an inspection, repair, alteration, or FFS assessment5 on an unfired pressure vessel, you need the appropriate ASME Code edition to be able to fully understand the design limits and best support your engineering judgment.
The main purpose of this article and Part 1, which was previously published in the January/February 2014 issue of Inspectioneering Journal, is to provide the reader with as much knowledge and as many tools as possible to know when you are being conservative and when you are not being conservative enough when carrying out activities on your unfired pressure vessels. Hopefully, this information will also help you select the best plan of action even if the original edition of the construction code is out of print. API 5102, Figure 8-1 and NBIC, Part 31, paragraph 3.4.2, can diminish the number of editions required for your library by authorizing the use of the latest edition of ASME Section VIII Div. 117 if all required conditions are met and understood.
Please remember that the post-ASME Section VIII Div. 1, 1999 addenda or pre-1999 addenda with the 2 following ASME Code Cases: 227824 or 229024 maximum allowable design stress, are based mainly on safety design margins of 3.5 instead of 4 (pre-1999 addenda) at room temperature, and can potentially result in thinner minimum thickness requirements than the original design.
The following article continues the discussion started in Part 1 and provides several important points you should consider in order to adhere to the NBIC Part 31 paragraph 1.2(a), API RP 5724 paragraph 4.6, and API 579-1/ASME FFS-15 paragraph 1.7.2 recommendations previously mentioned.