Inspection, Maintenance, and Repairs
This domain tests how boilers are inspected, how condition is evaluated, and how repairs are controlled. Expect internal and external inspection, hydrostatic testing, non-destructive examination, remaining-life calculations, and code repair requirements.
Inspection
An inspector looks for cracks, corrosion, erosion, overheating, scale, sludge, refractory damage, and leaking joints. The boiler must be cooled, drained, ventilated, isolated, and cleaned before internal inspection. External inspection covers fittings, supports, insulation, piping, and safety devices. A hydrostatic test may be required after certain repairs or alterations.
Repairs
Pressure-part repairs follow the National Board Inspection Code and ASME requirements. Repairs generally require a qualified welder, approved procedure, non-destructive examination, and an R-stamp holder where the rules require it. Post-weld heat treatment may be needed. Documentation must be retained.
Worked example: A shell course was originally 0.500 inch thick. The minimum required thickness is 0.375 inch. Current ultrasonic thickness is 0.410 inch, and the measured corrosion rate is 0.010 inch per year. Remaining life is (0.410 - 0.375) / 0.010 = 3.5 years. The boiler may remain in service with monitoring, but plan repair or replacement before the margin is consumed, and recheck if the corrosion rate changes.
Traps: welding pressure parts without an R-stamp or approved procedure; painting over cracks; skipping non-destructive examination; using an average thickness that hides a local thin area; returning to service without the required inspection.