Maintenance, Inspection, and Testing
Routine versus code-driven work
Daily and shift duties are operator work: water column and gauge glass blowdown, low-water cutoff test, bottom blowdown, water treatment testing, burner and flame-safeguard observation, and an accurate log. Periodic work includes safety valve pop testing, internal and external inspections, hydrostatic testing, refractory and tube cleaning, soot blowing, and combustion tuning. Repairs to pressure parts are controlled by the National Board Inspection Code (NBIC) and require an authorized inspector and, for weld repairs, a certified welder plus approvals and hold points.
Tests you must know
- Hydrostatic test - commonly 1.5 times MAWP on new or altered construction; it verifies tightness, not strength, and must never be used carelessly on an old firetube boiler.
- Safety valve test - the valve must open and reseat cleanly at its set pressure.
- Accumulation test - with firing at maximum, the safety valves must keep pressure from rising more than about 6% above MAWP.
Traps: a safety valve that weeps should be repaired or replaced, not adjusted by the operator; try levers only while attended. Water treatment neglect - scale, oxygen pitting, carryover - causes most premature failures. Keep the log and inspection certificate current and available; inspectors look for both.
Rule of thumb: if a test result surprises you, repeat it before you write it down - but never write down a result you did not actually observe.