Boiler Material

Copper

chet86 asks:

How much stronger is Type K over type L copper tubing? Only 0.009" difference in the wall.

From gwrdriver:

Let's assume for the moment you are looking for a boiler barrel (The barrel is the long'ish, tubular, front part of the boiler). If you run it through the applicable formlae for boiler barrels you will find that Type M is actually sufficiently strong for 100psi steam. But because there are always other forces acting on the boiler, both during and after construction, as Bill has just mentioned, I don't use Type M. All three types meet the basic strength requirements, but the extra rigidity and weight of Types K and L allow me to handle the material a little bit more like a solid and machine and work it with less concern for deformation. My personal preference is Type L for barrels and Type K for flues. I can usually get Type L locally but the Type K for flues almost always has to be ordered.

Steel

Keyhole boiler inside view. Photo by Marty Knox.

What not to use

Harold V writes:

It's not a good idea to use brass in a boiler, as it can suffer de-zincification (and failure). I expect the pieces you have are made of bronze, not brass. Bronze does not suffer the same fate.

References

• "Boiler", Wikipedia