Welding Thermowells to U-Stamped Pressure Vessel
Welding Thermowells to U-Stamped Pressure Vessel
(OP)
We have a new U-Stamped pressure vessel in our facility. Due to service requirements, it was PWHT.
For several reasons, the vessel arrived without the thermowells welded to the vessel (although the coupling for the thermowell was welded).
We are trying to decide the fastest and most cost effective way to weld the thermowells to the vessel and still meet B&PV code. The concerns, amoung others, is the affect of the new weld on PWHT, the need to hydrotest after the weld, and NDE requirements.
Suggestions would be appreciated.
For several reasons, the vessel arrived without the thermowells welded to the vessel (although the coupling for the thermowell was welded).
We are trying to decide the fastest and most cost effective way to weld the thermowells to the vessel and still meet B&PV code. The concerns, amoung others, is the affect of the new weld on PWHT, the need to hydrotest after the weld, and NDE requirements.
Suggestions would be appreciated.





RE: Welding Thermowells to U-Stamped Pressure Vessel
Did you look @ API-510?
There is a way around hydro testing with doing more NDT's.
Cheers,
Faraz
RE: Welding Thermowells to U-Stamped Pressure Vessel
RE: Welding Thermowells to U-Stamped Pressure Vessel
RE: Welding Thermowells to U-Stamped Pressure Vessel
Based on U-1(e)(1)(a), the opinion was expressed that this thermowell is not included in the code. Thoughts on this please.
RE: Welding Thermowells to U-Stamped Pressure Vessel
Refer to interpretation VIII-1-89-115, which is quoted here: thread292-262542: Welding pipe to pressure vessel nozzle. (Sorry no link as eng-tips is blocked in the country I'm in, and am using a proxy server)
RE: Welding Thermowells to U-Stamped Pressure Vessel
Any welding would be subject to the applicable code. In the case of welding pipe to a pipe stub nozzle, a piping code would apply rather than the vessel code. You'd need to either hydrotest or pneumatic test, or do the special NDE/sensitive leak test etc. to avoid a hydrotest per that piping code.
But what code would apply to welding a thermowell into a (presumably) socket welding or threaded coupling? Is that a matter for the owner to decide?
What if the thermowell is to be full pen welded into the shell or head? Surely in that case, both the thermowell and the full pen weld are subject to the requirements of the vessel code?!
RE: Welding Thermowells to U-Stamped Pressure Vessel
RE: Welding Thermowells to U-Stamped Pressure Vessel
Any welding to the vessel mentioned above is either under API 510 or the NBIC (National Board Inspection Code) and Jurisdiction rules, if applicable, will be followed. A re-hydrotest is not required for this activity, and would serve no useful purpose. NDT would be required.
Most likely, the designer of the vessel needs to be contacted to determine if local PWHT or an alternative PWHT method can be accepted. There is not enough information regarding process application and service conditions to provide an opinion.