welding of 304 SS with 316 filler 1

[shajanps]

Experts,
Please advise me whether Er316L filler material shall be used for welding SS pipe of 304L type. Normal practice is to use 308L filler but now some joints are already welded with 316L.so now I am trying find the possibility to justify it through a new Wps which will use 316L filler. None of the electrode manufactures manuals also recommending such usage...please share your knowledge in this subject.

 

[BigInch]

No. If you truly need 304 pipe, 316 in joints is a very bad solution.

you must get smarter than the software you're using.

 

[gtaw]

The major difference between type 304 and 316 austenitic stainless steel is the molybdenum in the 316 alloy. The moly should have no affect on the weldability, but it can provide a basis for galvanic corrosion in that it represents a dissimilar metal.

I have a couple of clients that weld 304 with 316 FM as their normal procedure will no apparent deleterious affects.


Best regards - Al

 

[BigInch]

I thought 304 had better pitting corrosion resistance to salts and better low temperature performance, so if 304 was specified with that in mind, then using 316 in the joints would not be ideal. Wrong?

you must get smarter than the software you're using.

 

[shajanps]

Thanks all. Main concern is about the effect of moli and a slightly lesser percentage of chromium in 316 Fm.

 

[gtaw]

It is always best to consider strength as well as chemical match when corrosion is an issue. The operating environment must be given due consideration, i.e., corrosion, strength, etc. The molybdenum in the filler metal resists sulfuric acid better than the 304 B.M., but if that is a concern, the 304 is a loser. If high temperature creep is an issue, the moly is fine, but again, the 304 is the loser in that department. Both the 304 and 316 have to meet the minimum of 75 ksi tensile strength at room temperature to meet Section IX requirements, but that was not defined in the original post.

316 wouldn't be my first choice, but you noted some of the pipe joints are already welded with 316 filler metal.

Following this thread is like listening to the Paul Harvey Radio Show; here's part of the story, stay tuned for the rest of the story right after the station break.

Best regards - Al

 

[BigInch]

I thought 304 was good for something other than low temperatures, but 316 does appear to be better at everything else.

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&ved=0CEUQFjAG&url=http://

http://www.parrinst.com/files/Parr_...qLlh7EDsoOjt3c6f9zrmIrA&bvm=bv.72938740,d.ZGU

http://www.bssa.org.uk/topics.php?article=100

you must get smarter than the software you're using.