Okay, here we go. Stainless Steel Tube Welding is a bit tricky. Some guys really like it. I never did. It is clean and exotic but there is so much that has to be watched.
The two most critical factors are these: Make sure your gap is slightly larger than your rod. Most of the time 2 times the rod size is a good gap. The second factor is a good purge on the inside of the tube.
I recommend carrying a role of masking tape about 3/4″ or 1″ with you especially when taking a test.
Anything you can bring yourself to make your test smoother will help you keep your nerves calmer through the test. We all know that taking a test is nerve racking. Even for an old pro.
Use the masking tape to close up the gap and both ends of the tube for a good inside purge. The better the purge the less possibility of sugaring or porosity on the inside of the tube. Always remember that any time you have to grind into the bevel and open up the bevel your test just became a bit more work. You already have a large gap because the stainless will draw up so much more than carbon.
If you can get away with placing only 3 tacks you are better off. Don’t be deceived to the idea that 4 tacks will help you.
Imagining that the standard tube test is taken in the 6G or Arkansas Bell position (45 degree), then place the bottom tack just offset to your weak side. By that I mean if you are weak using your left hand which will be the right side of the tube, than place the tack off center going up that weak side. This will cause you to weld less on your weak side.
If you don’t fully understand what I am saying for this post, I will explain more about this in a video but for now someone asked me to touch on this because that individual is going to take a welding test pretty quick. He asked me to give some tips.
So you place the tack at the bottom and then in a triangle pattern place the other two tacks. One at 10:00 on the left side from the bottom like the bottom would be the 6:00 o’clock stop and the right tack at 2:00.
This will leave the top open and give a smoother transition without a tack to grind out of your way. The top is the easy part of the weld.
The next tip I would give is this. When tig welding stainless, it is easy for the coupon to get to hot and then the stainless has a tendency to sag on the inside of the tube leaving excess penetration.
A great tip in tig welding is this. When striking up an arc with the tungsten you don’t have to keep the arc buried in the bevel to keep it going. If you were to move the cup on your tig rig away a little bit allowing the metal to harden or not melt but yet keeping the arc going, you can let the metal cool if it gets to hot, but you can also keep welding and get it over with.
Every tig welder knows that once you feel good about the root pass, the rest is gravy.
Don’t forget to keep the purge going until you get the hot pass or even the test completed.
316 ss is a typical middle of the road stainless. Be glad it isn’t 317L or 344.
Keep your tungsten sharp at all times if you can. I would make sure I have a bundle already sharpened when you show up to test.
Part of being a good welder on a construction job is looking like a good welder. Take pride in your appearance.
Wear a good welding cap. Starch your shirt up real stiff. Make sure all your tools are in order before showing up. I mean you are a surgeon dude. Act like it. Take pride in your skill. A good tig hand can call his shots.
Don’t get flustered even if the QC is breathing down your neck. Be nice to that guy. He can be your best friend or your worst nightmare. Pray before you get started. Get a good nights rest. If it is hot. Bring some cool water with you and drink drink drink. You will stay cooler. Be confident and God will bless your hands and eyes if you ask him. I could blow your mind with some stories. Anyway. I hope this helps, now go tear it up.