Welding fuel tank threaded flange

[rodsmith]

I'm concerned about warping these flanges when I weld them to the tank. I know to tack it well, and weld it in small segments. Is preheat recommended or not, do heat sinks help? Hopefully someone in the group has successfully done this.

Rod

[Zzz]

Have you picked out caps yet?

[fairchild]

Could you weld the flange on the sheet before the tank is built or closed ? If so- you could put a bolt and fender washer through the neck so the perimeter flange could be squeezed down to the sheet.
Tim