Welding AISI 4130 weldneck flange to ANSI line pipe

[engr2GW]

Hi all,

It is always recommended that when tieing line pipe to the wellhead by welding the last wellhead 4130 flange weldneck to A106 grade B pipe, that the weld has to be pre-heated and post weld heat treated, preferably in the shop.
Is it possible to do this welding in the field without the heat treating and be fine or is should that recommendation be considered a requirement?
Of course this bothers on the chemistry and mech. properties of the 4130 being an unassigned material, not the 106B which is a P1 material.

Thanks you.

 

[metengr]

mysarah;
What is the thickness of the 4130 weldneck flange? You should at least require a local preheat of 300 deg F minimum for the 4130.

 

[engr2GW]

Thickness: 0.55" sometimes a little more, and other times a little less.

 

[metengr]

Run a weld coupon on the above and evalute bend specimens and hardness w/o PWHT.

 

[engr2GW]

I did run a weld coupon with PWHT and with a max of 250 Vickers hardness in mind, I got numbers ranging from 230 to 247, that is with PWHT

 

[engr2GW]

and that was with TIG root and 7018 fill and cap. Another reason why I'm asking about shop welding is because since no cellulose soduim electrode is recommended like 6010, a process like TIG, etc will probably work better in the shop.

 

[metengr]

Well, you have your answer. Why can't you perform PWHT in the field? GTAW can be done in the field.

 

[engr2GW]

It can with portable equipment, but isn't it going to be more expensive? not to mension cumbersome...

 

[metengr]

mysarah;
You need talk with qualified mechanical contractors that can provide welding/PWHT in the field. Portable equipment today is easily mobilized, and ready for use in the field. I would not reach a final decision used until I at least talked with several contractors that know your situation.

 

[stanweld]

The GTAW process is used in the field all the time. But why don't you provide the spool with the dissimilar weld in the shop? To meet your hardness limits, PWHT will be required.