Filler Metal Selection 1

[Terrywis]

We are welding 1 1/4 Cr 1/2 Mo pipe (SA335 P11) Everything I read tells me to use Low Hydrogen 80 series filler.
Another company started this job using 90 series filler under the theory that stronger is better and it was easier for the Welders to use. I was always taught that you should not use filler metal that is too strong compared to the base metal. The site Engineer wants an explination why we are using lower tensil strength filler. Does anyone have a simple explanation on this

 

[stanweld]

Using a 90XX-B3 filler metal is not recommended for making P11 pipe welds for the following reasons. Greater preheat temperatures will be required to prevent cracking. Higher PWHT temperatures are also required. Use the 80XX-B2, matching chemistry fillers.

Note that the 80 series is also substantially stronger than the P11's minimum requirements.

 

[metengr]

....and you should specify low hydrogen filler metal, as indicated by the H4 suffix designation.

 

[Mr168]

To add a bit, the notion that the 90XX is easier to run than the 80XX has no merit whatsoever.