NBBI Inservice Inspector (IS) cheat sheet

NBIC is organized into Part 1 (Installation), Part 2 (Inspection), Part 3 (Repairs and Alterations), and Part 4 (Heating Boilers); the current edition is 2023 with supplements.

NBIC applies to boilers and pressure vessels after they are placed in service; new construction requirements come from the ASME Boiler and Pressure Vessel Code, not NBIC.

The Inspector's role: verify that inspections, repairs, and alterations comply with NBIC; the Inspector does not design or perform the work.

Jurisdictional requirements: where a state or province has adopted NBIC, its rules govern; NBIC itself is not law until adopted.

Inspection intervals: internal inspection of power boilers generally every 12 months, but jurisdictional rules may extend to 24 months under certain conditions; heating boilers often 24 months or longer.

NBIC Part 2 defines inspection methods: internal, external, and pressure tests; the Inspector must review operating history and previous inspection records.

Repair and alteration definitions: a repair restores a component to a safe condition; an alteration changes the item from its original design (e.g., increasing MAWP, changing service).

NBIC requires that repairs and alterations be documented on the appropriate NBIC forms (e.g., R-1, R-2, R-3, R-4) and that the Inspector sign off where required.

NBIC Part 1 covers installation of new boilers and pressure vessels, including foundations, piping, and safety valve requirements.

Maximum allowable working pressure (MAWP) is the maximum pressure at the top of the vessel at the design temperature; it is determined by the weakest component using the applicable ASME formula.

Minimum thickness for a cylindrical shell under internal pressure: t = P R / (S E - 0.6 P) per ASME Section VIII Div. 1, where P is internal pressure, R is inside radius, S is allowable stress, and E is joint efficiency.

Corrosion allowance: remaining thickness below the minimum required thickness (including corrosion allowance) indicates the need for repair, rerating, or retirement.

Safety valve capacity must equal or exceed the maximum steam or pressure generating capacity of the boiler; for pressure vessels, relief capacity must handle the maximum expected overpressure scenario.

Hydrostatic test: typically 1.5 times the MAWP for new vessels; for in-service repairs, the Inspector may require a hydrostatic test at 1.5 times MAWP or a pneumatic test at 1.25 times MAWP with special precautions.

Visual inspection includes checking for cracks, distortion, corrosion, leaks, and condition of supports, insulation, and refractory.

Non-destructive examination (NDE) methods: visual (VT), ultrasonic (UT), radiographic (RT), magnetic particle (MT), liquid penetrant (PT), and eddy current (ET); the Inspector reviews NDE reports.

Boiler external piping: ASME B31.1 governs; the Inspector verifies that piping is properly supported and that expansion joints and anchors are in good condition.

Record review: the Inspector must examine the manufacturer's data report, previous inspection reports, and repair records before signing an inspection certificate.

A repair restores a boiler or pressure vessel to a safe and operable condition without changing its design parameters; an alteration changes the design (e.g., MAWP, temperature, service fluid).

All repairs and alterations must be performed by an NBIC-certified repair organization (R stamp holder) using qualified procedures and personnel.

The Inspector must be notified before the start of a repair or alteration that requires inspection; the Inspector reviews the proposed procedure and qualifications.

Repair procedures must include welding procedure specifications (WPS) and procedure qualification records (PQR) per ASME Section IX; welders must be performance-qualified.

Post-weld heat treatment (PWHT) may be required for certain materials and thicknesses; the Inspector verifies that PWHT was performed per the applicable code.

NDE requirements for repairs: the Inspector may require RT, UT, MT, or PT depending on the type and location of the repair; acceptance criteria are per the original code of construction.

Alterations require a new or revised Manufacturer's Data Report and a new nameplate or stamping; the Inspector must approve the alteration before it is placed in service.

NBIC forms: R-1 (Repair), R-2 (Alteration), R-3 (Repair of pressure relief devices), R-4 (Repair of boiler external piping); the Inspector signs the appropriate form.

The Inspector must verify that the repair organization has a valid R stamp and that the scope of work is within the stamp's authorization.

Pressure relief valves (PRVs) protect boilers and pressure vessels from overpressure; they must be set at or below the MAWP and have sufficient capacity to relieve the maximum expected flow.

Safety valves are typically used for steam service; relief valves for liquid service; safety relief valves for both. Pilot-operated and spring-loaded designs are common.

Set pressure: the inlet pressure at which the valve starts to open under service conditions; for steam, set pressure must not exceed MAWP; for pressure vessels, it may be up to 110% of MAWP under certain conditions per ASME Section VIII.

Accumulation: the pressure increase above MAWP during relief; typically limited to 10% for pressure vessels and 6% for steam boilers (with variations for fired vessels).

Blowdown: the difference between set pressure and reseating pressure, usually expressed as a percentage of set pressure (e.g., 2-7% for steam safety valves).

Capacity certification: valves must be capacity-certified by the National Board; the capacity rating is stamped on the valve and must be adequate for the application.

Inspection of relief valves: the Inspector verifies that the valve is the correct size and set pressure, that it is properly installed (vertical, unobstructed discharge), and that it has a valid test tag or certification.

Testing: relief valves are typically tested at intervals determined by the jurisdiction (often annually for steam boilers); the Inspector may witness tests or review test reports.

Repair of relief valves: must be performed by an R-stamp holder or a qualified valve repair organization; the valve must be reset and sealed, and a new tag attached.