Quote:
Originally Posted by Badbubba
From my experience, you can not cut stainless with torches, you basically melt your way through it. You need a plasma cutter or air arc for cutting. As far as metal fatigue (cracking/splitting,warpiing), due to heat cycling, it will eventally happen to all metals. Some faster that others. It all depends on the composition of the metal, the weld material, the consistancy of the weld beads and a few other factors. I work in an electrical maint. dept. as a predictive maintenance reliability cordinator for a Steel Manufacturer. Lots of heat cycling where I work, so we need to know the metallurgy of materials before we use them in critical areas. We've gotten some low quality metal products, including conduit, that have been nothing but headaches. Btw, running rigid & coated is slightly harder than emt.
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The OBX headers I received a few weeks ago were cut with a cut off wheel. Not a plasma or gas cutting system. The lack of weld root / penetration left plenty of room to see the scared edges of the pipes.
It is very common and I bet most header manufacturers use that same method. They may plasma cut the flanges but the piping is very most likely cut by wheel or band saw.
And on "all metals", not true. As a professional weld inspector, I look at new production welds as well as 50+ year old in service welds. You could replace all metals with cost efficient alloys and have a fairly true statement.