CB tubes are cracked

[nazawale]

Recently upon annual maintenance on our Cleaver Brooks boiler, tech found various tubes are cracked. I am wondering why. Did someone try to introduce cold water at start up or condensation mix up? Any clue or experience

[Control Man]

Are they cracked on the rolled ends of the tubes at the rear tube sheet ?

[slimwoodie]

prolly just age ..

most CB's on the job are made in the 1960's ..

[Control Man]

Well if they are from the 60's then they are not the original tubes so the old age factor is not likely the cause.

Some CB firetube boilers have a flaw in them , the rear tube sheets were not aligned properly on the vertical plane , this caused the tubes to crack on the roll edges of the 3rd and 4th pass and the welded tube rolled edges on pass 2.

Another cause was buildup of crud at the tube and rear tube sheet on the water side , this caused the area to overheat as the heat was not transfering to the water.

Retubed so many CB boilers in the early to mid 70's that I still have nightmares of hauling the tubes up the stairs to 18th floor boiler rooms