Which electrode?

Date 04-24-2004 14:57

If you look in D1.1 code book it will give you tables of grades of steel and electrodes that are acceptable to use. It can also depend on your procedures.

By MBSims

Date 04-24-2004 17:34

You don't say what grade of SA-182 is being welded, such as F11, F22, etc. There are many grades of SA-182 ranging from low alloy steel, to high alloy steel to stainless steel. Since you said Cl. 3, it may be either F11 or F22. If so, you could weld it to SA106 Gr. B pipe with either E7018 or the matching filler for the fitting (E8018-B2 for F11, E9018-B3 for F22).

By Mark31

Date 04-25-2004 14:28

Your right I'm sorry it is F-22
How do you handle the two different tensile strenghts one being 60 psi and the other being 75 psi. Should you still use 7018 rode.

By MBSims

Date 04-25-2004 16:28

The joint is only as strong as the weaker side, in this case 60 ksi for the A106. E7018 easily provides enough weld strength to match the weaker side. There are other considerations to selecting electrodes than just tensile strength, though. You have to consider the chemical composition of both metals and what the final composition of the weld will be after a portion of both base metals is melted and mixed with the electrode composition. In this case, the weld deposit will contain some additional Cr and Mo from the F22 fitting. This would not produce an undesirable chemistry in the final weld. However, if you were welding some other combinations there could be some metallurgical issues that would affect electrode selection. AWS has a good book on the subject titled "Welding Metallurgy" by George Linnert. There were 2 volumes in the 3rd edition and AWS has only published Volume 1 in the 4th edition, so if you can find a good used copy of Volume 2 from the 3rd edition you should buy it.