Welding of dissimilar mat. Hastelloy B2 to Hastelloy C2000

By hasway Date 03-17-2008 10:13

Dear My Expert Friends,

I am having a problem to get Hastelloy C2000 plate within short duration. Our scrubber is made up from Hastelloy C2000 and it's really in bad shape, i.e. there is hole at the neck area, and we need to replace it with new plate (insert patch weld). And, in our stock, we have a surplus of Hastelloy B2 plate, and since we got no time, we plan to replace exisiting C2000 (damaged portion) with B2. The problem is now is to get the correct filler rod for joinig these 2 disimillar plate, we have no idea which electrode will suit best for the welding either ERNiCrMo-17 or ERNiMo-7. The second question is, if we weld dissimilar material, do we have to come out with new WPS and PQR?

Thanks and really need some answers and explaination from you guys.

Hasway

By 803056

Date 03-17-2008 21:27

This is when you need to consult with the manufacturer's technical department. They are in the best position to tell you whether the materials are compatible, what filler metal is recommended, and whether the material, Hastelloy B2 is even recommended for the application.

What welding standard are you welding to?

If you are working to ASME, check the P number for each of the materials you mentioned. If they are contained in the same P number categories, no additional qualification is necessary (assuming you already have one for the Hastelloy C2000). If the two materials are contained in two different P number categories, then a new PQR and WPS is required.

Best regards - Al

By RBeldyk (**)

Date 03-18-2008 02:55

This get tricky.

Shooting from the hip... weld the combination of B-2/C-2000 with ERNiCrMo-17 , you are matching the C-2000 material and overalloying the B-2. But it is not that simple, One really need to know the environment, trace chemical etc.

Several problems to think about:

1. Chromium Carbide formation in the C-2000 with the diluted carbon from the B-2 alloy.
2. Weld HAZ Stress Corrosion in the B-2 material
3. One also needs rapid heating to avoid some detrimental tranformation reactions of the B-2/C-2000 diluted material

http://www.haynesintl.com/weldinginformation.htm

The second question is, if we weld dissimilar material, do we have to come out with new WPS and PQR? Yes, and do some immersion and Stress Corrosion testing as well. Note that the SCC testing should be fairly quick. A failure by SCC can be catastrophic.

By hasway Date 03-18-2008 03:23

Guys, I really appreciate your replies. I will try to communicate with the manufacturer and find out the recommended step to use to weld these materials.

thanks