Fire Tube Boiler!

[MirjafariSM]

Hi Dears
We have a 10 ton fire tube boiler with 7bar pressure.
8 tubes have some leakage in tube to tube sheet joint. We expanded them but it did not solve our problem!
How many times we can expand tubes?!
Can we do hydraulic test several times? (If the answer is yes, with which pressure and temperature?)
thanks all

 

[Duwe6]

If the tubes have been rerolled [reexpanded] three times, quit rolling them. Nothing more will be gained.

The best pressure to test the tubes at is the Set Pressure of your relief valve. The Boiler Feed Pump can supply this easily, and there is no limit to haw many times you can pressurize the boiler to this pressure. Take care to not use very cold water. Some materials used in boiler construction may brittle-fracture at 15-deg. C or colder. Much safer to use 25-deg C or hotter water. If the tubes keep leaking, consider seal-welding the end of the tube to the tubesheet.

 

[metengr]

How long has this boiler been in service? Have you inspected the tubesheet for ligament cracks? Are you sure you have tube to tubesheet leaks?

 

[MirjafariSM]

Thank You Duwe6/metengr
our boiler has been in service for 2 years.
we are sure that there is leakage from tube-tube sheet joint.
I agree with Duwe6, we have to consider seal welding.

 

[GenB]

sealweld as a temporary fix.okay.
if in the US or Canada, consider permitting
weld job done by a R or S stampholder,
if the boiler inpector find out you welded w/o permitting, you may be in a lot of trouble and may loose the whole boiler or may have to do the whole tubejb. just an advise.

 

[chicopee]

While seal welding is a surface welding job and not a strength related welding job, be sure that the tube ends have enough wall thickness so as not to burn thru. Be sure to notify the AI to determine if this is a repair of a routine nature.