Inoxidable Steel Tube Pipe needs a good purge on inside of the root pass in order to keep it from getting crapped up.

Inoxidable Steel Tube Pipe welders called it "sugaring" and the technical term is oxidation or "granulation".

Either way its ugly stuff. It not only inhibits flow of liquid, but it provides a place for bacteria to grow. For food grade piping, that is not cool.

For food grade and other Inoxidable Steel Tube Pipe applications, getting the root purged right is a must.

The inside of the weld must be silver and shiny or the inspector aint gonna let it ride. And even if there is no inspector when the weld is made and you get away with a sugared weld, later on when the swab tests are done and little critters are seen under a lab microscope, the company gets shut down and you don't get any more work from them.

That should be incentive to do it right.

Seriously, when stainless steel pipe is purged right, it's fun to weld and flows like honey.

If it's not purged right, all the fun is gone and it's like welding in a bowl of cornflakes.

I did another story recently about a contractor who was installing stainless steel pipe in a wash station for trucks that hauled chocolate milk and other food products. It falls right in line with this page about purging stainless pipe.

His welds looked great and he got his purge using aluminum tape and a lot of hard work, but he definitely could have saved some time and aggravation if he had these slick little purge plugs.

OK, Let's talk about the built in diffuser for a minute.

Why do you need a diffuser? Why can't you just stick the argon hose in the end of the pipe and crank up the flow?

Here's why… Remember that argon is heavier than air and fills a container much like water would. If you stuck a fire hose in a pipe, you never would get all the air bubbles out. But if you ran a soft stream of water from a garden hose, it would fill every nook and cranny and completely displace the air.

That's a rough analogy but I think you get the point.