Adding a New Drain Nozzle to a Registered Air Receiver
An R-stamp holder is asked to modify a 1995 ASME Section VIII Division 1 air receiver in a manufacturing plant. The vessel is 42 in. inside diameter, 0.50 in. shell, MAWP 200 psig, and is registered with the National Board. The owner wants a new 4-in. NPS drain connection in the lower shell to replace a 2-in. connection that is frequently plugged. The proposed opening is in the shell, not on a longitudinal seam, and the R-stamp holder proposes a pad-reinforced nozzle. The holder tells the owner this is a 'repair' because it restores reliable drainage, and will file an R-1 report. The inspector notes the original NB-2 data report lists only the existing 2-in. drain and does not show the new opening. The jurisdiction requires NBIC Part 3 for repairs and alterations and requires the authorized inspector to review the work. The plant wants to install the nozzle during a 48-hour shutdown.
1. Is the new drain connection a repair or an alteration under NBIC Part 3? Explain the consequence for the work plan.
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It is an alteration. NBIC Part 3 distinguishes a repair, which restores an item to a safe condition within the original design, from an alteration, which changes the design and can affect pressure-retaining capability. Adding a new 4-in. opening and reinforcement changes the shell design and the opening reinforcement; calling it a repair because it improves drainage does not change the classification. The work may still be done by an R-stamp holder, but it must be handled as an alteration: a qualified engineer must prepare the design and reinforcement calculations per ASME Section VIII Division 1, the authorized inspector and jurisdiction must review and approve as required, and the work must be documented on the required National Board R form. The holder's statement that an R-1 alone makes it a repair is wrong. The inspector should stop the job until the alteration package is complete; a 48-hour window does not justify starting without approvals.
2. What technical items should the inspector require before accepting the completed nozzle?
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The inspector should verify: design calculations showing the opening is adequately reinforced and not in a prohibited location; a qualified WPS/PQR and welder performance qualification; material identification and traceability; fit-up and welding inspection; required NDE (surface and volumetric as specified by the design/code); any required PWHT; and a hydrostatic or other pressure test required by the code or jurisdiction. The inspector should hold witness points for fit-up, NDE, and test. The R-stamp holder must complete the R-1/alteration report and any required nameplate or registration update. If the 48-hour shutdown cannot accommodate these steps, the schedule must change; shortcuts such as skipping NDE or hydrotest are not acceptable. The inspector should also confirm the vessel's MAWP remains 200 psig after the alteration; if reinforcement is inadequate, the MAWP cannot be retained.