Classifying Four Jobs on a 250 psig Drum

1. 6 in → 10 in nozzle: alteration. It changes a design dimension and the reinforcement requirement. Requires the inspector's authorization and jurisdiction concurrence, new design calculations from the original construction code, an NBIC alteration report with supporting calculations, and a nameplate/record update if design conditions change.

2. Lap patch over 0.36 in metal: repair. It restores the vessel to its original design condition; design pressure, temperature, and geometry are unchanged. Requires the inspector's authorization and an R-stamp repair organization, but no jurisdiction concurrence. Design the patch per VIII Div. 1, evaluate PWHT (not required originally, but weld thickness and heat input still need review), and specify NDE.

3. Tray support rings and a permanent support lug welded to the shell: alteration. These impose loads on the pressure boundary that were not in the original design, and the lug in particular is a permanent structural attachment. They need engineering evaluation of local stresses at the attachment welds, plus inspector authorization and jurisdiction concurrence. If an evaluation showed the loads were already covered by the original design, the classification would shift toward repair - the test is whether the design basis changes.

4. Service change to wet sour hydrocarbon at 500 ppm H₂S: alteration, and likely a rerating. A service change that imposes design requirements not considered originally - sour service metallurgy, hardness limits, possible PWHT, SSC/HIC susceptibility, revised corrosion allowance - changes the design basis. Requires engineering evaluation of H₂S partial pressure against the applicable NACE document, inspector authorization, jurisdiction concurrence, and a new nameplate plus revised records if MAWP or MDMT changes.

Pattern to remember: repair restores; alteration changes the design basis (geometry, loads, service, MDMT); rerating changes a rated limit and always ends with a new nameplate.

API 510 requires repairs and alterations to be tested in accordance with the applicable construction code; the construction code, not convenience, decides what test is required.

• Job 1 (nozzle replacement): pressure test required. The pressure boundary is cut and re-welded in a region carrying shell reinforcement. Default is a hydrotest per VIII Div. 1 at the code test pressure, with full NDE first. An alternative (e.g., a sensitive leak test plus full radiography of the new welds) can only be justified in writing by the inspector with jurisdiction concurrence, because this is an alteration.
• Job 2 (lap patch): pressure test required as the default for a shell weld repair. Omission is arguable only where the repair is genuinely minor and fully examined - and the inspector must document the code basis. A patch near the head-to-shell weld is not a good candidate for waiving the test.
• Job 3 (attachments): no pressure test in the ordinary sense if the attachment welds are non-pressure-retaining and the inspector determines the pressure boundary is unaffected; NDE (PT/MT) of the attachment welds is still required, and full-penetration welds into the shell would change that answer. Confirm the evaluation did not require reinforcement of the shell.
• Job 4 (service change): no pressure test arises from the service change itself, but if the evaluation results in a new MAWP or new MDMT, the rerating brings its own code-required test and a new nameplate.

Document the decision, the code clause relied on, and who approved any omission. 'We did not think it was necessary' is not a basis.

Yes to authorization; no to self-inspection.

• Holding an R certificate qualifies the organization to perform repairs and alterations under its quality program. It does not transfer the owner/user's authority to decide what may be done to the vessel. Each repair and alteration requires the API 510 inspector's authorization before work begins, and the inspector's review of the completed work - including the repair organization's records, NDE results, and test results - before the vessel returns to service.
• Alterations additionally require jurisdiction concurrence. The R stamp does not substitute for that.
• Independence: the inspector must be an employee of the owner/user or of an authorized inspection agency acceptable to the owner/user - not of the organization performing the work. An in-house inspector employed by the same maintenance group that welded the patch cannot be the inspector of record for that job; the owner must use an independent inspector for those items. Otherwise the owner is certifying its own work.
• Records: the completed package - repair/alteration report, WPS/PQR references, NDE reports, PWHT records if applicable, pressure test chart, and the updated thickness and inspection history - goes into the vessel file, with the CMLs re-baselined to post-repair readings and the next inspection interval recalculated.