a cut-out for a pipe connection hit weldments of the line pipe

[etrobal]

we needed to cut-in a 24-inch diameter pipe to an existing 48-inch diameter pipe thru a 45degree lateral connection. a cut-out was necessary with reinforcing plate for the connection.

the cut-out on the existing 48-inch diameter, unfortunately, hit the single longitudinal weld of the pipe; further, the pipe to pipe circumferential weldment of the 48-inch pipes was also hit. so we now have a hole where the welds' continuity might be compromised.

will there be an effect on the integrity of the welds? we have put online the system already and am requesting information or advices on how to safely operate the system due to the cut-out of the welds. we flushed grind the longitudinal and circumferential welds to fit the reinforcing plate. will that be enough?

the system design pressure is 214 MPag (310 psig) and the design temperature is 216degC (420degF).

before i shoot the same message to the metallurgist or quality control engineer, i'd like the opinion of the experts here at mechanical.

thank you, once again.

 

[unclesyd]

Did you do any NDT on the welds in the 48" line prior to installing the lateral and doubler plate?

 

[metengr]

There shold be no adverse effects from this operation on existing welds provided NDT was performed prior to welding and final NDT was performed in accordance with the code of construction requirements.

 

[etrobal]

sir unclesyd, you are correct on the piping thread. we had failures in the stub-in weld, four times repaired. no stress relieving was done and it was put on line.

thanks sir unclesyd and sir metengr.

the existing longitudinal weld of the 48-inch pipe was factory ndt'd and the pipe to pipe circumferential weld passed all our ndt requirements, in accordance to the code.

but, the stub in connection was repaired four times, thence no stress relieving was done, and the system pressurized.

the stub pipe diameter, by the way,is a 36-inch pipe, not 24 as previously posted. please see attachment.

any advice or comment are most welcome.

thanks again.

 

[metengr]

etrobal;
What is the material of construction and wall thickness? PWHT because of multiple weld repairs may or may not be necessary. Also, what code of construction was the line modified under?

 

[etrobal]

sir metengr, the pipes are API 5L and the B311 power piping code was used for the design of the system. multiple weld repairs were at the stub-in area and not in the longitudinal or circumferential welds. thanks sir.

 

[metengr]

etrobal;
Was PWHT required by B31.1 for the stub in weld based on nominal thickness? If no PWHT was required by Code, you are fine with one repair or multiple weld repairs, it makes no difference.

If PWHT was required by Code and you performed none OR made subsequent welds repairs after the stub-in was PWHT, this is a different matter to discuss.

 

[etrobal]

again, thank you. indeed, the replies has been very enlightening.