Repair and Alteration Requirements (NBIC)
Repair vs alteration
NBIC Part 3 defines a repair as work that restores a boiler or pressure vessel to a safe, operable condition without changing its design parameters. An alteration changes the pressure-retaining capability or design: changing MAWP or design temperature, adding or relocating openings, changing service, or changing material. Alterations require design calculations and AI approval; repairs generally follow the original code of construction.
Technical controls
- Welding: WPS/PQR per ASME Section IX and welder performance qualification.
- Heat treatment: PWHT per the original code or NBIC Part 3 when required by thickness or material.
- NDE: method and extent per the original code or NBIC Part 3, with personnel qualified to ASNT SNT-TC-1A or CP-189.
- Pressure test: hydrostatic test after completion unless the AI accepts a documented exemption.
- Documentation: R-1 form describing the work, code references, and test results.
Worked example
A vessel originally built to ASME Section VIII Div. 1 needs a new 2-inch nozzle. Because this creates a new opening in the pressure boundary and changes the design, it is an alteration. The R stamp holder obtains design calculations including reinforcement, has the AI approve them, welds with a qualified WPS and welder, performs RT per the original code, hydrotests, and completes the R-1 marked as an alteration. Calling it a repair to skip design review is a mark-losing error.
Traps
- Misclassifying an alteration as a repair to avoid design calculations.
- Ignoring the original code of construction when choosing NDE and PWHT.
- Using a welder whose qualification has lapsed.
- Forgetting that some repairs require AI hold-point inspection before welds are covered.