Stainless steel pipe welding is gravy work. Always has been. Always will be.
If you are able to do it and do it well, you are the man and also you will never go hungry. However it takes some attention to element to do it right.
The main thing that separates the boys from the boys or should I say, the real welders from the rod burners is the willingness to follow procedures for welding stainless steel. Procedures like waiting for the pipe to chill in between passes, keeping the new tip of the rod shielded with argon, snipping the tip of the tig welding rod when it gets crapped up, keeping your tungsten sharp.
One of the principal procedures I’m talking about is PURGE. Stainless metal absolutely needs to be purged with argon gas as a way to prevent sugaring. Sugaring is also called granulation however it is severe oxidation it doesn’t matter what you call it.
You cant even get away with tack welding without an argon purge that shield the back side or inside of the pipe. So how do you do it? How do you protect the back side with argon?
Normally it is completed with aluminum duct tape. The ends of a stainless metal pipe are taped shut and the entire inside is purged with argon gas. Even the opening in the pipe joint itself is taped in order that argon can fill your complete pipe and push out any oxygen. The tape is peeled back just sufficient to get a tack once the pipe is purge enough.
What is sufficient? The only way to tell for sure is with an oxygen analyzer. A bic lighter will not do the trick. Even 2% oxygen content will blow out a bic lighter. And 2% oxygen will lead to a black root pass.
There are another down and dirty ways to check the purge however an oxygen analyzer is the certain way.
Listed here are a number of tips that will assist you to get a good purge on the stainless steel pipe you weld.
Make positive there is no such thing as a water inside the pipe…not even a drop. One single drop of water will throw a monkey wrench in your purging until it evaporates. Keep in mind what’s in water? Hydrogen and oxygen.
Poke a vent gap in the uppermost place you’ll be able to find. Think of argon as if it was water. Because it is heavier than air, it will fill up any house like water, displacing the air as it fills each nook and cranny.
More purge gas flow is not always better. A high and turbulent flow of argon will not necessarily purge a pipe quicker than a lower flow rate. And a diffuser on the tip of the tip of your argon hose normally means that you can use a higher flow rate. A homemade diffuser could be made with some stainless metal wool , some perforated stainless sheet, and a bit of sheet metal.
Once you confirm a great purge, you might be ready to tack. Peel the tape back just enough to tack and let cool a bit and re tape. Then tack once more a hundred and eighty degrees apart. Proceed until all tacks are in place.
More suggestions for welding stainless pipe…
Laying an 1/eight inch wire in the root works better than dipping a 3/32 inch rod.
Use a feather edge bevel. No land needed
You can fix areas that do not penetrate by re welding
Use only stainless metal wire brushes and only use files that have only been used on stainless steel.
Use just enough amperage. Utilizing an excessive amount of amperage will overheat the stainless metal and make things go south quick.…