American Welding Society Forum
which will be a suitable filler ER90SB9 ? or ER80SB3L ? for welding P91 pipe to F22 valve
Actually, ER80SB3L is recommended for welding the 2 1/2 Cr-1 Mo steel forgings (F22). The filler metal recommended to weld the P91 material, 9Cr-1Mo and V+Nb+N, is ER90SB9. It's your choice, but with all respect, I would recommend the ER90SB9. The P91 is the higher alloyed material and it is usually recommended to match the filler metal to the higher grade.
In ASME Section B31.1, there is a temperature limitation with respect to using low carbon filler metals when welding P22 materials.
Note 17 in Table A2: For temps above 850F, the carbon content of the base metal and, where applicable weld filler metal shall be 0.05% or higher.
The 80S-B3L specification (SFA 5.28) limits carbon to 0.05% max. Before it is used in systems with design temp > 850F, you would have to obtain actual certs for the wire and make sure the carbon is not out of spec low.
For F22 base metal, C=0.15%. For P91 base metal, C=0.08-0.12%. I still recommended using the ER90SB9 filler with the higher carbon content because it can be used at "high" or "low" temperature service. ER80S-B3L is a "low carbon" filler. P91 is a high temperature base metal using Nb as a stabilizer, therefore, matching filler should be used that is compatible with high temperature service if this is the case.
Chuck, you are absolutly right. I have seen more main steam failures because ER80SB3L was used instead of ER90SB9. Just talked to a NDE person that came back from Idaho this last week end. He had to do some PMI on a main steam failure that happened because of using ER80SB3L instead of ER90SB9 on a P22 to P91 joint.
P.S Chuck, thanks for the S.S info. I recieved it today.
Hey Jim !!!
Thanks for the support. I look forward to meeting you in Seattle. I'm not sure how this Texas boy is going to act in the far north west, but I will just follow your leads. I'm glad you received the stainless steel literature. Part, or all of that is going to be included in my presentation. Keep in touch, my friend.
In the past, the company I work for,always advised to use the 'higher' spec filler for dissimilar welds of this type!
About seven years ago, this changed to to using the 'lower' of the two!
I could never really understand this change and I still think, to this day that cmeadows is correct in what he states!
By the way, I personally have noted that welds made since this change, are more likely to in-service failure!
Interesting that a F22 valve is being welded to P91 pipe. I hope there is a F91 isolation valve somewhere upstream.
I've been a Welding Engineer for almost 33 years and I've never heard of any advantage of using a "lower" alloyed filler metal in most cases. Since most every filler metal is overalloyed in regards to the comparable base metal, it is almost always advisable to use the highest alloyed metal when welding two dissimilar metals. Rod, I do not doubt what you are saying, but this is news to me. When using the lower alloyed filler metal one will compromise the integrity of the higher grade of the two dissimilars. Depending on the heat input, using the lower grade can, due to the loss of alloying agents in the weld arc, one can actually be below the chemistry of both metals and that ain't good....
What is the Minimum Design Material Temperature( MDMT) of A335 Gr P22? Where it is Mentioned?
It is found in ASME Sec II part D.
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