need help building a wood fired vertical fire tube boiler

[steampower88]

Well I'm actually a welder by trade so tig and stick welding are not a issue. My uncle has also welded for 40 some odd years plus he has built boilers and actually a couple patented parts. So the welding part of it doesn't scare me one bit. Would flux core mig with co2 shielding gas work instead of 7018 rod. Its a process used in a lot of structural steel work and would cut down on starts and stops. I'm just trying to do some research on how to build one this way I know what the hell he's talking about lol. I really appreciate all the help from you sir and I hope I can build one of these soon, who knows maybe I can get a boat and play around with that as well. It looks like a swell time and you guys are very passionate about your hobby

[Lopez Mike]

Yeow! A real welder.

As long as the MIG filler is as strong as the usual old 7018 and you get the penetration, I don't see why not. These welds are in places where the stresses aren't that high. The seriously important welds are factory supplied when you buy the shell materials.

Bothers me that no one else has jumped in here.

Fred??? Are we planning a bomb?

[fredrosse]

"Would flux core mig with co2 shielding gas work instead of 7018 rod. "

Flux core MIG uses no shield gas, so the statement is confusing? For steel welding I think a CO2 - Argon mix is proper. HOWEVER..........

MIG with a small machine is not recommended for a steam boiler. Big MIG machines, feeding 0.045 wire or larger can be used, but none of this is with flux-core. In general stick welding provides the penetration needed for boiler pressure vessels. Special welding equipment, such as submerged arc machines are also used, but I don't think many small shops have this type of equipment.

When I had my boiler made at a ASME Code shop, they wanted at least 1/8 clearance between the tube sheet and shell pipe to get the full penetration weld. I had the tubesheets made with 1/16 clearance, so I had to do lots of grinding to get the clearance the shop wanted, at least I won't forget that lesson soon. That was with 3/8 inch thick tubesheets, 3/8 inch wall thickness seamless pipe for the shell. I would strongly recommend that proper boiler materials be used for the shell, firebox (A106 Gr B seamless Pipe) and tubesheets (SA 285 or SA 516 Gr 70 plate), and tubes (ASTM A178). Stainless is outlawed according to the ASME Code for virtually all boiler wetted parts with few exceptions.

[steampower88]

There is a process of .045 flux core that uses co2 shielding gas as part of the process. I have no problem welding with 7018 its a nice running rod. Thanks for all the help I posted in a separate thread of the engines I'm looking at converting for this project. Please weigh in on what you think

[Oilking]

Dualshield uses 75%/25% Argon/CO2 with fluxcored wire. Used on structural work, but don't know about code boiler work? In theory it allows the weld to cool under a slag cover as the gas envelope moves on. Kinda like a belt and suspenders.

Dave

[Oilking]

steampower88,
You may want to contact Doug Blackburn of Lacenter WA, whitefireantiques@netzero.net, he owns a full size American Steam Fire Engine that is in working order.

Dave

[steampower88]

Thank you Dave I'll be sure to do that

[ccdewitt]

The ASME code does not provide for MIG with or without core or shield gas for welding of unstayed surfaces in fired pressure vessels. Stick is always the best bet for hobby boiler builders. Sub-arc are is allowed but few of us have that level of welding in a home shop.

Although the ASME code can seem over cautious it is based on 100 years of experience and I strongly suggest that it be called upon for reference.

[Lopez Mike]

Amen.

I would go so far as to do a few test welds using the same techniques and materials as your boiler. Tig root weld and 7018 filler weld. Cut them up and look them over. Even with years of experience a little basic stuff never hurts.