> €€
> MR> I vaguely remember coming across a furnace once that I think
> vented
> MR> steam and condensate to the atmosphere instead of
> recirculating it. That
> MR> could have only meant it was rather low pressure. As far as I
> understand
> MR> boilers, if it uses a safety relief valve, it requires some
> IQ and a
> MR> license to fix it.
 
> Piping in refineries and chemical plants use that method for
> keeping pipes from freezing. They run tubing along the pipe and
> run steam through it and on the end is a steam trap which opens
> every so many seconds and lets some steam or condensate out. They
> also heat some outbuildings using a steamline to a radiator
> or Modine with a steam trap on the end. ...Ken
 
Most low pressure steam tracing DOES go to steam traps. A steam trap being a 
mechanical device that waits until a certain volume of steam has condensed 
back into water. Then it opens and can either vent the hot condensate to 
atmosphere, or in most cases back into the return loop of the boiler 
feedwater. EVERY pipeline in a manufacturing facility of any size WILL have 
an overpressure device, whether it be a rupture disc on a vessel, or pressure 
relief valve. Their insurance carrier gets to say "tough luck" if accidents 
happen as a result of pipes or vessels rupturing because of no overpressure 
device.  
As a side note, as steam pressure increases, it's temperature increases. That 
may have be a limiting factor in the example that MR gave above.
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