Maintenance, Inspection, and Testing
What this domain tests
Maintenance, Inspection, and Testing asks how a boiler is kept reliable and proven fit for service: planned maintenance, water-side and fire-side inspection, non-destructive testing, hydrostatic testing, and record keeping.
Core rules
- Planned maintenance covers lubrication, bearing and coupling checks, vibration monitoring, alignment, refractory repair, gasket and handhole renewal, and instrument calibration.
- Water-side inspection looks for scale, sludge, pitting, caustic attack, tube sheet ligament cracks, and staybolt condition. Fire-side inspection looks for soot, overheating, bulging, and refractory spalling.
- Non-destructive testing: ultrasonic thickness for tube wall loss, radiography for welds, magnetic particle for surface cracks in steel, dye penetrant for non-magnetic surfaces.
- Hydrostatic test: water at a safe temperature, safety valves removed or gagged, pressure raised slowly to the test value and held, with no permanent deformation allowed.
- Records: boiler log, repair history, valve test results, and calibration data must be retained for the jurisdiction.
Worked example
A boiler has a MAWP of 200 psi. For new construction, ASME Section I sets the hydrostatic test at 1.5 times MAWP, so 1.5 x 200 = 300 psi. The vessel is filled with water, vented, warmed to avoid brittle conditions, and pressurised slowly to 300 psi, then held while all joints are examined. In-service tests after repairs follow the NBIC and the local jurisdiction, and the safety valves must be isolated so they are not damaged.
Traps that cost marks
- Confusing MAWP with normal operating pressure when setting a test pressure.
- Hydro-testing with safety valves left in place, which ruins them.
- Testing a cold boiler with cold water and risking brittle failure.
- Inspecting only the fire side and never opening a handhole to see the water side.