Is it possible to use a spot welder attach it to copper ring to heat up mild steel tube 72mm in diameter need it to get around 240 degrees cel ?

if not use a microwave transformer pass direct current hook it up to the copper coils to act as induction heater

Any other very cheap alternatives are open the aim is to get a mild steel tube to 240 cel doesn't have to be through induction

 

If the spot welder has the capacity, and you could find a way to place the M.S. between the electrodes fixed securely and apply power, the secondary can be anything from a few hundred amps to many thousand, dependent on the capacity.
The MOT will not act as an induction heater on its own.
Max.

 

Is it possible to use a spot welder attach it to copper ring to heat up mild steel tube 72mm in diameter need it to get around 240 degrees cel ?

if not use a microwave transformer pass direct current hook it up to the copper coils to act as induction heater

Any other very cheap alternatives are open the aim is to get a mild steel tube to 240 cel doesn't have to be through induction

Id use a propane torch with a flame spreader. Possibly two if you have a friend.

 

240C 464 F. with a 74mm 2.84" Depending on the tube length if you could clamp each end and run a current through the tube it should heat up, I have no idea how much current would be required. We used this method to create super heated steam in stainless steel tubing. I don't see induction being used here.

Ron

 

Is it possible to use a spot welder attach it to copper ring to heat up mild steel tube 72mm in diameter need it to get around 240 degrees cel ?

How long is the tube area that needs heating?

What's in it or passing through it?

How quickly do you need it to get to 240 C?

How accurate does it need to keep the temperature once at 240 C?