Keeping the area near the weld cool

I own a jar of some stuff called "Heat Fence". It looks like modeling clay. It's supposed to keep heat from traveling down a bar. I've not tried it yet.

See

GWE

I used to use something like the "heat fence" on sheetmetal and O/A welding. It really worked well! Unfortunatly, it was full of asbestos and went the way of the buffalo. A few years later I tried what was at the auto-body supply place as a replacement and it was more like paper mache, and it did not work worth a damn. Maybe in the last 20 years somebody has come up with a usable replacement for the asbestos stuff.

I think I would try the "heat fence" and if it didn't work, a really wet rag tied tightly around the steel. Keep the welding times short and the rag wet, and it should be OK.

Good Luck, Bob

I think a moist cloth will work. An alternate is some chunks of copper clamped to the vertical posts. I would try the moist cloth using some scrap. So you can find out without messing up the final product if it doesn't work.

Dan

I had another idea. If you have access to an open end of the vertical sections, perhaps you could wad up some aluminum foil into a plug and jam it in so it's between the weld zone and your PVC collar, and then plumb up a stream of air to blow into the vertical section. The air would go in, hit the plug and have nowhere to go but back out again, but it would carry a lot of heat with it. Better would be a water spray.

GWE

As others have suggested, wet cloths and or filling or spraying water inside the post to cool from the inside will be of help.

IMHO the greatest problem is with the time that you will be applying heat. You did not state how big your TIG torch is but normally TIG tends to be a slow process, especially on tubing of the size and wall thickness you are working with. I would suggest you consider welding with stick electrodes as you can make a weld faster which will limit the time that you will be heating the post. Depending on your experience, 3/32 rods will allow you to use lower current but you may prefer to use 1/8 and higher current and just move faster. The heavy flux from a 7018 will also help to shield the weld from rapid quenching even if you apply water after putting in a bead. I would think you could weld a full 2" long bead then quench and cool completely before welding the next side.

Good luck,