Question on Material for Steam Generator Tube

Here is a start: http://www.engineeringtoolbox.com/astm-steel-piping-tubing-d_469.html. This list gives several types of steel and stainless steel for high temperature service, but it doesn't mention actual allowable temperatures.

Thanks!

My advice is talk to your material supplier.

If Milo's around he'll know as much as anyone about the performance of metals and can advise you.

But, I suspect that he would tell you this, too.

You are not allowed to use 300 series stainless but 200 series is ok for steam. I do not have the regulations in front of me but the ASTM boiler regulations lists the different alloys and where they are allowed to be used. Dave

A213/A213M-01a looked promising; it mentioned superheater service.

Thanks! To get good efficiency, I'll need to get the pressure & temperature of the steam as high as possible, and I want to make it as robust as possible also. If I spec the generator tube to handle the temperature and pressure when "dry" then it's not going to fail easily.

I would seriously question the 1100degF when dry - I suggest that the flame temperature of biomass will be considerably higher than that & any steel material used should take that into consideration, then plus 10-25% just in case

Thanks. I'm going to build the combustion chamber first and add the boiler tube to it later. That way I can nail down the exact operating temperature. The primary combustion chamber may get that hot, but there are no tubes in there. That will be steel with a castable refractory coating. The exhaust from the primary combustion chamber (gasifier) will be mixed with preheated air, and secondary combustion will take place. That's where the hot end of the tube will be. Normally it will have superheated steam in it for cooling, but just in case I want to make sure that a "dry" tube won't burn through.