An Old Interpretation Cited Against Current Alteration Criteria
An owner's engineer wants to add a 2 in. NPS nozzle to a 48 in. diameter, 150 psig air receiver built to ASME Section VIII Division 1. The vessel carries National Board number 54,210 and is in a jurisdiction that has adopted the NBIC 2023 edition. The nozzle requires a reinforcement calculation and local post-weld heat treatment. The owner cites a 2011 NBIC interpretation, issued under the 2010 edition, stating that 'adding a nozzle to an existing vessel is a repair when the opening is within the original shell thickness and no re-rating is required.' The Authorized Inspector has determined the work is an alteration because it changes the vessel configuration and requires a reinforcement calculation. The owner argues the 2011 interpretation is binding and that an R-1 is sufficient. The AIS must resolve the conflict between the old interpretation and the current code text and decide how to proceed without delaying the project unnecessarily.
1. How should the AIS weigh the 2011 interpretation against the 2023 code text?
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The 2023 edition text controls. An interpretation is the National Board's official explanation of the code text as it existed when the interpretation was issued; it is not a code revision and does not amend later editions. The 2011 interpretation was issued under the 2010 edition, and the definition of alteration may have changed. The AIS should first read the 2023 definition and the Part 3 alteration criteria. Adding a nozzle that requires a reinforcement calculation and post-weld heat treatment changes the configuration and affects the vessel's design, which points to alteration. The owner's quotation of an old interpretation is not a binding determination for a 2023-adopted jurisdiction. The AIS should document the code basis and explain why the old interpretation does not control, rather than simply rejecting the owner's position.
2. What is the proper process to obtain a current, authoritative answer?
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The proper path is a written interpretation request to the National Board, submitted through the Authorized Inspection Agency, describing the vessel, the proposed nozzle, the reinforcement calculation, and the exact code question. The jurisdiction may also issue its own written position, and the jurisdiction's position controls for that state. The AIS should not treat an informal email or an old published interpretation as a current binding answer. Until a written answer is received, the conservative course is to process the work as an alteration, with design calculations and the appropriate alteration data report. The request and response should be retained in the job file. If the owner wants to proceed as a repair, the AIS should obtain the owner's written acknowledgment of the risk and should not sign an R-1 that the AIS believes is the wrong record.
3. If the owner proceeds as a repair and files an R-1, what are the consequences?
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If the owner proceeds as a repair and files an R-1, the registration may be rejected and the jurisdiction may require stop-work. The alteration would lack the required design review and the correct data report, and the vessel's record would be inaccurate. The AI who signs an R-1 for alteration work risks commission action, and the Authorized Inspection Agency risks accreditation action. The AIS should refuse to sign, notify the owner and repair organization in writing, and state that an alteration report and calculations are required. Insurance coverage and jurisdictional acceptance can also be affected. The AIS should preserve the correspondence and the technical basis, because the dispute is likely to be reviewed after the fact and the record should show that the AIS applied the adopted code rather than the superseded interpretation.