Welding Q125 Casing

[PDA1950]

We are building a fixture for surface testing of downhole equipment. Our client has furnished two joints of 9-5/8 Q125 casing. The fixture requires that flanged be welded to the ends of the joints. We only need the strength of A36 plate at the welded joint. What is a recommended welding process to achieve a sound weld?

 

[metengr]

Shielded metal arc(SMAW) or stick welding process. Do you intend to use slip on flanges or butt welded flanges?

 

[PDA1950]

I was thinking of beveling the end of the casing and then do V weld plus a fillet.

 

[PDA1950]

Ho, the flange would be butt-weld type for just a flat plate.

 

[PDA1950]

Sorry about the typing problem. My keyboard has sticky keys.

 

[PDA1950]

Would you please recommend a weld wire or rod material and do we need to do any pre or post heat?

Thanks

 

[redpicker]

You will need to get a chemical analysis of the casing to be sure. In all likelihood, you will need a preheat and most likely a post heat. If you cannot get a chemical analysis, assume it is 4140 and you won't crack it. You are likely to lower the strength of the Q125 a bit more than you need to, but it should still beat the heck out of A36.

What I would say, just knowing Q125, would be Preheat 500F. Post heat 1000F.
Q125 will likely be in the 0.30-0.35%C range, with perhaps 0.8-1.0% Cr. so cracking without any Preheat is likely. I'd postheat above 950F since it could well have Vanadium (~0.05) and Molybdenum (~0.15) since they need to hold 125PSI min yield and have impact strength.

 

[metengr]

I would strongly suggest you qualify a welding procedure using the above just to make sure you have no ductility issues with the Q125 in the weld region.

 

[redpicker]

I would strongly suggest you qualify a welding procedure using the above just to make sure you have no ductility issues with the Q125 in the weld region.

Absolutely!

 

[blacksmith37]

API Committee never permitted welding on Q-125.