TIG (GTAW) girth welding of tube OD 150mm and wall thikness 8mm in carbon steel API 5L X65 1

[kjell123898]

Hi,
I work as a welding engineer in Aker Solutions Norway Umbilical Dep. and wonder if anyone has experience in GTAW welding of pipes in API 5L X65 material without subsequent local heat treatment (PWHT).
The actual dimension is OD 150mm and wall thikness 8mm and looking for good and feasible tips before welding qualification
I'm asking you in order to obtain knowledge and be well prepared for future inquiry

 

[weldstan]

Why do you need to PWHT? What is the service? Generally the filler metal used is AWS Class ER80S-D2.
I assume the pipe is seamless. PWHT may lower the strength of the X65 pipe if thermo-mechanical processing was used in its manufacture. That is easy to address by requiring tensile testing of the pipe with the simulated PWHT that you intend to use.

 

[kjell123898]

hi weldstan,
appreciate your response
we have not taken any final decision at its discretion whether to switch from super duplex (UNS 32750) to API 5 X65 quality but trying to be slightly ahead if it is possible to TIG weld X 65 quality without subsequent annealing (PWHT) when this additional process would delay implementation dramatically.
Each individual tubes are bevelled and welded together to a long string (reeled onto big reels) which subsequently put into an umbilical that will be installed subesa later on.
We will of course do mandatory weld qualifcation in accordance with ISO 15614-1 and do all required NDT and mechanical test as well.
The filler as you proposed is a good alternative but unsure we can get in on 15 kg spool. I know we can get AWS Class ER80S-Ni2 or Ni1 but need to figure out further properties in respect to PWHT

Kjell Grønvold

 

[weldstan]

If potential for wet H2S, do not use ER80S-Ni2. ER80S-Ni1 has also been extensively used. I would not recommend X65 for wet H2S service without PWHT.
Changing to X65 from super duplex is a really big change.