P5b to P8 welding

Date 11-02-2001 13:01

Ok guys, your input on my 9Cr preheat problem was invaluable; and I would like to thank you all for sharing your knowledge with me on that question. To update, the weld has been rejected and cut out. Hardness tests are being done on the parent metal to ascertain there are no problems there.
Now another interesting issue has reared it's ugly head; the engineering firm ordered weld-in flow nozzles made from 316L SS. They are to be welded into a joint in the 9Cr pipe. I have already rejected the contractor's 309 rod procedure and they are currently seeking a WPS that is acceptable to us. I have heard that this dissimilar metals weld can be made with an inconel filler, but I would appreciate any input. Knowledge is good.
Roy

By M-Squared (**)

Date 11-02-2001 15:02

This joint can be welded using ErNiCr-3 GTAW, or ENiCrFe-3 SMAW (Nickel Base "A" "82 or 182"). We use these fillers for all our dissimilar welding of 9Cr materials to SS, and have had no problems associated with the welds. Since you are welding an "L" grade SS, PWHT at 1400 F should not be an issue with the SS concerning carbide precipitation.

When we get into a situation where we are welding a non "L" grade SS to a 9 Cr material we will butter the 9 Cr piece with the Nickel welding rod (two layers) and PWHT the 9Cr piece. After PWHT, we weld the 9 Cr piece to the SS with the Nickel weld rod. This joint then does not require PWHT. This technique can also be applied to the "L" grade material if you are not comfortable with the idea of performing the PWHT on the "L" grade SS.

By chall

Date 11-05-2001 13:25

We use the same set up as M-squared and have had good results. Once again I'd like to point you in the direction of Euroweld. Roger Swain or Bill Newell can shed all kinds of light on this topic. They will discuss the pros & cons of PWHT on P8 material in terms that make sense. Tele: (704) 662-3993.