ASME IX, QW-423 allows the use of alternate base materials for welder quaifications. This would qualify a welder for welding stainless, however most companies view it as bad practice and require welders to qualify using P-8 base material. 309 welds easily to carbon steel and will pass the bend test. But why would you not use a back purge?

To qualify to GTAW weld on SS with purge, ASME Sec IX allows you to qualify using carbon steel for the base metal, ANY F-6 filler metal (ER70 S or 308), and no purge. However the SMAW portion requires that you use an austenitic filler metal.

Since there is no purge, it may be difficult to get the root pass to flow well on the inside so pay extra attention to getting enough metal inside to grind down for the coupons. The SMAW stainless is probably the most difficult part for me. The ease of welding varies a great deal between manufacturers. Practice running the rods uphill with stringer beads, use a short an arc as possible and when you notice your welds starting to sag, let it cool a little.

There is actually no need to run the root with stainless wire. It's just an added aggravation. The reason they are not having you purge is probably to allow you to put roots in CS pipe with or without purge.

One of the differences you will notice from the test and actual welding of SS pipe is how long it takes to cool down. CS pipe is a little easier to weld on because of its higher thermal conductivity which causes the weld metal to freeze faster.

I've never been (slick) at stick welding SS pipe. But I haven't come across any that were with every welding rod available.

Have a nice day

Gerald AUstin

http://www.weldinginspectionsvcs.com