Maintenance, Inspection, and Testing
Maintenance and inspection items test preparation, documentation and acceptance criteria.
Preparing a boiler for internal inspection
Shut down and cool slowly, isolate and lock out all energy sources including fuel and electrical, drain, wash waterside surfaces, remove handhole and manhole covers, obtain a confined space entry permit, and provide ventilation and a standby attendant. The jurisdictional inspector needs a clean, cool, safely accessible boiler plus the previous inspection record.
What inspectors look for
Waterside: scale, sludge, pitting, cracking at tube ends and ligaments, rolled joint weeping. Fireside: corrosion, refractory deterioration, tube bulging or blistering, sagging, support and casing condition. Also inspect the water column, gauge glass tappings, safety valve outlets, blowdown piping, vents and drains.
Testing
- Hydrostatic test: typically 1.5 times MAWP for Section I and IV boilers; use water between roughly 70 and 120 deg F to reduce brittle fracture risk, vent all air, and hold while joints are examined.
- Safety valve: hand-lift lever test, pop test and accumulation test; setting and sealing by a qualified organization. Never gag a valve permanently and never test by blocking a discharge.
- Non-destructive examination: ultrasonic thickness, radiography, magnetic particle and dye penetrant for crack detection.
Records
Logs of water tests, blowdowns, safety valve tests, repairs, and inspection findings are legal records, not paperwork.
Traps
A hydrostatic test is not a substitute for internal inspection, and a boiler that passed hydro does not thereby have capacity or relief protection confirmed.
Worked rule
For a 200 psig MAWP boiler, hydrostatic test pressure is 200 x 1.5 = 300 psig, with all safety valves removed, gagged per code, or isolated so they are not subjected to test pressure.