22:19 Oct 31, 2011 

Thanks for this. I was quite certain that there isn't a 'boiler formula' as such. This relates to a series of holes in a platen, see other question, so in fact is a series of holes that are under pressure. No boiling water just helium gas at very low temperature.

22:10 Oct 31, 2011 

There must be several hundred formulae (stress, strain, creep, fatigue, you name it) for both thin and thick-walled pressure vessels, most of which can be applied to a boiler (which is just a hot pressure vessel). Ypu could just call it "pressure vessel stress formula", or maybe "the formula used for boilers" if you want to keep the chaudière bit.