Tube failure by foreign matter blockage & hanger block failure

Failure by foreign matter
Cause :
Cleaning tool stuck inside tube.

Preventive measures :
1. Check every tubes in the boiler throughly before boxing up.
2. Have an organised system or checklist on tools usedd for boiler cleaning.

Hanger block failure
Cause :-
1. Operating on high loading & overheating the furnace.
2. Operating on too high positive draft in the furnace (puffing furnace draft)
3. Poor workmanship on the hanger block.

Preventive measures :-
1. Keep boiler loading at below 90%. Avoid overloading boiler on prolong period.
2. Ensure furnace draft at least - 5 mm/H20.
3. Check hanger block design / specifications & installation accordingly.