steam line - safety valves
steam line - safety valves
(OP)
Where in the ASME code can I find : when there are 2 or more high pressure boilers connected to a common header and the boilers are of different design pressures that a steam header safety valve(s) must be installed





RE: steam line - safety valves
RE: steam line - safety valves
RE: steam line - safety valves
RE: steam line - safety valves
RE: steam line - safety valves
You can put a relief device on the ajoining piping provided that:
1. That the relief device(s) are of sufficient relieving capacity that they can relieve the total capacity of all of the boilers and that they are set to relieve at the pressure rating of the lowest rated boiler and that when relieving the pressure in the boiler is not more that 10% above the boiler rating.
2. The piping is of sufficient size, i.e. not less than the inlet of the relief device. In this case the piping leading up to the header could be the size of the relief valve on each boiler with the header size being the same size or large of the relief valve inlet. See UG-133 an 134.
3. If you are leaving the relief devices on each of the boilers in tact the individual boilers are protected and there can be intervening valves between the boilers and the relief devices on the piping.
4. Calculations should be done to determine the effect of the piping on the relief capacity of the valves due to frictional pressure drop in the piping which will result in a lower inlet pressure at the valve. This is true of the relief valve outlet piping also.
RE: steam line - safety valves
RE: steam line - safety valves
It is possible that the 250 psig units were not designed to produce 100% MCR steam flow at 150 psig- the drum steam water separators might have excessive carryover at the lower pressure. In that case, the 250 psig unit would need a presure reuceing valve at the outlet and then additional 150 psig relief valves would be provided at the outlet of the pressure reducing valve, as spelled out in B31.1 or B31.3.
RE: steam line - safety valves
J. Alton Cox
President
DeLuca Test Equipment
www.delucatest,com