be sure to check out these other videos on tig welding stainless steel
This page is all about TIG welding a Stainless steel outside corner joint on 16 ga. (1.6mm) .063" thick.
The outside corner joint is used a lot for stainless kitchen equipment, industrial computer cabinets, tanks, reservoirs, battery boxes, and marine equipment.
When a stainless steel joint is welded, in order to preserve the stainless qualities, it is necessary to provide some type of protection on the back side.
Argon is best but sometimes it just isnt practical of feasible.
Aluminum or copper backing is the next best thing to having argon purge on the back side.
but sometimes there is just no substitute for an argon purge.
And when you need a purge, the easiest way to do that is with a dual flowmeter.
Before I go any further, let me list these rules for welding stainless that will help keep it corrosion resistant
in the pic below, you can plainly see the difference between a purged weld and one that is sugared
when stainless steel is molten, if not protected by inert gas, the chromium reacts with oxygen and other elements in the atmosphere and what you get is an ugly oxidized rough weld on the back side.
And it is not just a surface condition that can be polished off.
Sugaring/granulation is a condition that goes deep and unless it is completely removed, it greatly affects corrosion resiistance and it also provides a nest for bacteria and microbes to grow.
Imagine a pharmaceutical factory making medications for the elderly and having this condition on the inside of tubing or valves.
Or how about a brewery or dairy making edible products with sugaring on the inside of their pipes.
It is completely unacceptable.
Now I am not saying that every stainless steel weld made requires argon purge on the back side.
Sometimes using aluminum or copper backing provides sufficient protection.
But there are certain applications where argon purging is the only way to get results that are satisfactory for the service requirements of the weld.
Nuclear piping, pharmaceutical, food service, semiconductor industries are a few industries that can simply not tolerate sugaring on the root of stainless steel welds.