[Steam-engine] lap seam boiler pressure

[Andre' Blanchard]

At 10:03 AM 7/8/2005, you wrote:
>Robert,
>
>I'm in agreement with you that the ultra-sonic tool is the best way to 
>determine boiler condition.  Myself, since I own one, I won't operate or 
>purchase an engine till I do a preliminary check.  That is unless a state 
>official or other qualified person has looked the boiler over and given 
>its approval to operate.  But, I don't agree with "You did a hydro at 200 
>psi, with an assumed operating pressure of 100 psi; that could ruin the 
>boiler right there."  If the boiler plate was .375" original thickness, 
>then the boiler can be assumed that the design pressure was 150 lbs., a 
>standard design pressure of the time, not to be confused with operating 
>pressure.  That would be a pressure either an official or an individual 
>owner determined to operate the unit at.  I know of engines here in 
>Minnesota that have safety valves set at lower pressures than the boiler 
>equates to.  Some do it because it was the safety valve on the engine when 
>they bought it or that was the size they had read!
>  y available to put on the unit.  Either way, don't always assume that 
> the pressure releif valve coincides with design pressure.
>
>As for lap seams.  Yes, many inspection agencies pay more attention to a 
>lap seam boiler.  But if the numbers work, then there won't be a problem 
>obtaining the desired pressure rating.
>
>Lawrence
>
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When putting a lower pressure relief valve on a boiler I would think that 
the size (diameter) of the relief valve may have to be increased.  As at 
the lower pressure the boiler will still be able to make the same number of 
lbs of steam per hour, likely even a little more.  But at the lower 
pressure the relief valve may not be able to flow enough to get rid of it.
Has this ever been a problem?
___________
Andre' B.  Clear Lake, Wi.