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Boiler Inspections
Internal and external inspections, preparation requirements, and what inspectors look for.
In this topic:
Types of Inspections
Boiler inspections are required by law and performed by authorized inspectors.
- Internal inspection: boiler is shut down, cooled, drained, cleaned, and opened
- External inspection: performed while the boiler is operating
- Certificate inspection: required to obtain or renew an operating certificate
- Insurance company inspectors and state inspectors are both authorized
Preparing for Internal Inspection
The owner/operator is responsible for preparing the boiler for the inspector.
- Cool the boiler down safely and completely
- Drain the boiler
- Remove all handhole and manhole covers for access
- Clean the waterside (remove scale and deposits)
- Clean the fireside (remove soot and combustite)
- Lockout/tagout (LOTO) all energy sources
- Provide adequate lighting and ventilation inside the boiler
- Have the operating logbook and maintenance records available
LOTO is ALWAYS required before entering a boiler for inspection or maintenance.
What the Inspector Looks For
The inspector examines all critical components and surfaces.
- Tube condition: corrosion, pitting, bulging, blistering, leaks
- Shell and drum condition: cracking, distortion, weld integrity
- Stay bolts and braces: cracking, wasting, tell-tale holes
- Safety valve condition and settings
- Condition of fittings: gauge glass, try cocks, blowdown valves
- Refractory condition (fireside lining)
- Nameplate data and MAWP verification
Tube Problems
Tubes are the most vulnerable component in a boiler because they are thin-walled and exposed to extreme conditions.
- Bulging: overheating causes the tube to swell outward — usually from scale buildup
- Blistering: surface layer separates — early stage of failure
- Pitting: localized corrosion from oxygen attack
- Bagging: sagging of flat surfaces from overheating
- Tube leaks: often caused by corrosion, erosion, or overheating