Repairs and Alterations
NBIC Part 3 separates a repair from an alteration, and that distinction drives everything: who may do the work, what design is required, which form is issued, and whether the item must be re-rated.
Definitions that matter
- Repair: work that restores an item to its original design condition - weld build-up of wasted area, a flush patch, replacing a tube or a shell section.
- Alteration: a change to the pressure-retaining capability or design - raising MAWP or temperature, changing dimensions, adding or relocating a nozzle, or changing service so the design basis changes.
The process
The repair organization must hold an R Certificate of Authorization, maintain a quality control program, and have an inspection agreement with an Authorized Inspection Agency. The design must be prepared by an engineer competent in the original code of construction. Welding follows qualified WPS/PQR and performance-qualified welders; NDE acceptance comes from the original construction code, not from Section V. Hydrostatic testing is required when the work affects the pressure boundary in a way the original code treats as requiring it. The AI accepts the work and signs Form R-1, the record of the repair or alteration, and the R stamp with the R-1 number is applied at the nameplate.
Worked example. A shop proposes to add a 4 in. nozzle to a Div. 1 shell. That is an alteration: a new opening changes the design. Required: reinforcement calculations per the original code (area replacement), qualified welding, NDE as the design specifies, R stamp, Form R-1 marked as an alteration, and - if MAWP or service changes - recalculation of relief capacity and re-rating of the pressure relief device.
Traps. Calling an alteration a repair to avoid design calculations; accepting welds on a Section IX coupon that does not cover the thickness or P-number; letting an R-1 be issued without the AI's acceptance; changing MAWP without touching the relief device.