Welding P5B To P5B

Date 03-07-2002 18:25

Can I fit and tack butt weld flanges to butt weld elbows before preheating to 400 F to start the weld out process?
We have never welded this material before and it would be easier to do this verses building fixtures to hold our parts until they reach 400 F so they could be tacked.

Any information would be very hrelpful.

Thanks R Butler

By pipewelder_1999 (****)

Date 03-08-2002 12:55

In my experience, if the WPS calls for preheat I preheat. I would suggest a local preheat to the area to be tacked.

The preheat will reduce the likelyhood of the tacks cracking.

The requirements you "MUST" follow are probably covered in the welding procedure and the applicable code. If there is not a welding procedure, I would suggest developing one.

The thickness of the base metal, welding process and joint geometry all affect the cooling rate of the weld. Thicker metals cool off quicker, GTAW cools of slower than SMAW, a 45 Degree included angle would cool faster than a 70 degree included angle.

Have a nice day

Gerald Austin

By RButler (*)

Date 03-08-2002 15:46

Thanks Gerald for the reply, I looked at the WPS and it does say preheat before welding so I will follow those directions.

Ron Butler

By Niekie3 (***)

Date 03-08-2002 22:32

Only in the case of thin materials should you take the risk of tacking without pre-heating, but as already stated: - If the WPS calls for it, then you had better do it.

Regards
Niekie