Properties of Stainless - Purging Stainless Steel

How the Tig Finger makes pipe welding easier

Good enough never is......What??

What does that even mean and how does it apply to this series on the properties of stainless steels?

Who came up with that saying anyway?

I get what they meant...you know, Go the extra mile, over deliver, build quality into everything....but sometimes you have to get the job done... and sometimes, good enough really is good enough.

..Hell, sometimes good enough is better.

Ever make a weld and then decide it didnt look all that good so you got out the grinder to dress it up? And then you got a little too happy with the grinder and put grinding scratches in places where they didnt belong. Like a mating surface, or a polished surface that made the grinding scratches look like Fidos butt?

The weld probably didnt even look that bad...If you would have just left the weld alone, it would have been a better job.

Thats just one example when good enough is better.

One of the properties of stainless steel is its tendency to sugar or granulate on the back side of a weld if not shielded with argon or protected with backing.

Purging the back side of stainless is the only way to make it shiny and pretty.

But sometimes the back side does not have to be pretty , just not ugly...not sugared up.

Even some nuclear pipe welding codes allow for purge gas to contain up to 1% oxygen. Did you know that 1% oxygen will turn a root pass gray and ugly? but according some welding codes, 1% is considered ok for many applications.

So if gray root pass welds are ok on nuclear piping systems, what about the extensions for the headers your brother in law wants you to weld for his Bucket T hot rod? Does the inside need to be shiny silver, or just not sugared? You feelin me?

We all want to do a good job and pay attention to quality where it counts dont we? But we also want to be productive and get things done.

There is a balance to achieve between production and quality.

Too much attention to every little detail and not much gets done.

Too little attention to details and quality, and things get done but come back to bite us in the ass....and we become known as a hack.

I never want to be known as a hack...never.

In this video on the properties of stainless steel, I show 2 ways of backing up stainless steel to prevent sugaring and granulation.

Neither yield a weld that is silver on the back..at least not every time. But both methods are quick and much easier than a total purge.

One method is to use a block of copper or aluminum for backing. Not the kind of backing that gets welded to the stainless,,. But Removable backing.

Copper and Aluminum are both so conductive that they work quite well as backing for welding stainless steel. Especially on gaps.

I recommend scrounging all the odd and ends of copper and aluminum you can find. It comes in very handy for backing material and to use as a heat sink too.

Copper tubing can also be used as backing material. In this video, I drill some small holes along a short piece of 1/4" copper tubing and attached a rubber vacuum hose that was hooked up to a victor dual flowmeter. It only takes about 5ch of flow rate to provide enough argon to purge with a setup like this.

The aluminum foil trough helps to keep the argon shielding in place on the molten metal....at least well enough to prevent sugaring.

The other option is to tape off all the openings and purge the inside completely with argon....but that is for next weeks video. exit properties of stainless and see the tig finger