PG-99 of ASME SEC I 2

[Mec.tec]

As per PG -99 of ASME SEC I the hydrostatic test of boiler cannot be conducted below 20 deg C.Now if the weather condition is not supporting the required temperature to achieve as required by code then is there any possible exemption in ASME SEC I for temperature that may be taken to account this problem?

 

[davefitz]

I am not sure, but I doubt it. There are available a few photographs of failed steam drums due to hydrotesting at below 20 C ( the one in florida in the 1970's comes to mind) , but there are also issues with the modern creep strength enhanced alloys of the HP main steam line ( P91), which may have marginally low ductility at temperatures below 20C.

To minimize the steam drum wall thickness ( and thus allow a faster startup time)very high strength carbon steel is used, but one issue that is inherited is lack of ductility below 20 C.

Another issue is that boiler fabricators and constructors use every loophole in the asme code to skip PWHT wherever permitted- one result is that there may be scattered components of the boiler that have brittle weld zones with pre-existing micro-cracks and pre-existing stresses from welding that have not been relieved.



"Whom the gods would destroy, they first make mad "

 

[metengr]

There are no exemptions or exceptions to Section I PG-99 for hydrostatic testing below 20 deg C.

 

[sharmass]

Refer Code Interpretation I-95-27:
Question: May pressure tests required by PG-99 be conducted using water at a temperature less than 70 deg F?
Reply: No.

There is no exemption.
I have worked at boiler assembly sites in sub zero temps. Had to use a hot water boiler and circulate it for couple of days before hydro test.