Nothing big going on is the shop today. But this one quick tig welding job came in so what the heck?
The welds were depicted in a drawing detail for some type of lid for a solvent tank and this is the only weld on the whole drawing.
Often times, welding symbols on drawings are full of errors....and sometimes there are no welding symbols at all. And sometimes there are only basic welding symbols but no real information on type or size of weld.
It's a problem sometimes, but sometimes its a blessing. Sometimes the customer just wants the part to work and does not really care if all the welds were done exactly to specification. The welding symbols dont really help in this case .
This is a simple job. A piece of 1/8" thick square tubing welded to another short piece that acts as a spacer....and that is welded to a stainless steel spring loaded latch.
But we can still find stuff to talk about.
For starters, those flare bevel welding symbols have the weld symbol placed on the arrow side of the reference line but the arrow is pointing to the wrong joint.
Like I said earlier, mistakes on welding symbols are pretty common. Its a lot less common in critical industries like construction of Nuclear Plants...but it mistakes still happen.
Next is the technique for tack welding. Blasting a quick tack weld with a tight arc and roughly twice the normal welding amps is a quick way to fuse joints together with a very small tack weld. ( the fit has to be tight, and you might want to practice on some scrap to get the hang of it before tacking live parts)
Next is using a magnet to identify metal. Carbon steel is very magnetic but stainless steel is non magnetic or slightly magnetic depending on amount of cold work.
see more tig welding videos
Some stainless steels are pretty darn magnetic (like 301, 410, 15-5,
17-4) but mostly you can get a pretty good idea using a magnet. The
latch was shiny with no plating. That usually means some type of
stainless steel. Using er309L filler rod is a good choice for tig
welding carbon to stainless steel. In fact, that latch could have been
made from a variety of alloys and 309 rod would still work. Its a good
rod to have around.
A while back, I did a video on removing a broken exhaust manifold stud that had a high carbon EZ out broken off in it. I used 309 rod to weld to the EZout fragments along with the broken stud and it worked great because the thing about 309 rod is that it wont harden from picking up carbon from a high carbon bolt or ezout.