Welding Tips and Tricks

Hey,
New member questions about a burner stand for a boil pot (brewing, fish boils, etc) I'm planning. Looking at using A36 for the frame and wondering if I might have a problem with weld joint cracking because of all the thermal cycling.

Is ER70S-2 the best choice for filler? Or would ER70S-6 or some other filler be better?

A36 is really easy for me to get hold of but would I be better off using something besides A36 for the areas that will see the most thermal cycling?

Should I be preheating before welding and letting the weld cool slow to prevent some micro cracks from starting?

If I design the stand right, hopefully I can accomodate for catastrophic failure (14 gallons of boiling liquid spilling) by making sure if a weld fails the house of cards doesn't collapse.

Lots of questions for my first time on this forum, I hope questions make sense.

grinder

No worries about heat cracking on low carbon steel. S-2 or S-6 will be fine.

Hat's the great thing about mild steel is it's not prone to that sort of thing. Also, the temps that steel will see during boiling etc. Will not even be close to getting hot enough to cause those kinds of issues. I'de be more concerned with rust from the heat cycling.

I'm not sure what temperature your system gets up to, but long term scaling has proven to be a problem in some heating systems. I've noticed this on my "used oil" furnace and the rocket stoves as per the following youtube videos. I use stainless steel for my hearth and have no issues. One of the following videos suggests the same.

https://www.youtube.com/watch?v=90R-uB6QMG0
https://www.youtube.com/watch?v=qsB_52F8liE
https://www.youtube.com/watch?v=A-oEn4sfu7g
https://www.youtube.com/watch?v=fVI9aVm_FZM
https://www.youtube.com/watch?v=rvPnP1eGUKw
https://www.youtube.com/watch?v=HWM3BELk8Uo

Werkspace has a point on scaling, but I don't think its a concern for your application. The propane burner I use for crawfish/crab boils is a good 20 years old, mild steel, and has the advantage of a threaded stainless gas orifice, so it burns consistently each time.

Heat cycles on mild steel are a non-issue in this use. My choice would be the S6 wire, since it should all be one-pass welds. Extra scavenging whether you need it or not, and no "multiple passes" to bury silicon inclusions.

If you like, I'll dig out the boiler stand and take a picture or two, but the design is pretty simple.

Steve S

Rocket Stoves are extremely efficient for cooking/heating.
(Very minimal smoke and very little wood fuel required.)
The following videos will explain their construction and operation.
https://www.youtube.com/watch?v=HWM3BELk8Uo
https://www.youtube.com/user/aproresearch/videos

Thanks all, good to hear my concern is not serious. My welding skills (lack of) are more of a factor than thermal cycling.

-If I decided to use 304 ss would there more chance of cracking?

-Those rocket stoves are pretty cool. If I didn't have NG or propane that would be a great option.

-Otto, did you suggest -6 because the A36 is likely to have more impurities (inclusions) even though I'll flap disc the mill scale off?