boiler safety valve rating 1

[wengineering]

boilers are provided with two safety valves, is each valve rated for 1/2 of the boiler capacity?

We have an existing boiler (80klbs/hr) designed for 1000 psig working pressure, but had been operating at 175 psig from the start. 20 years later, boiler was converted to high pressure operation (900 psig). Now, we want to return it back to 175 psig working pressure. Do we need to reset the safety valves? If we do not, boiler feed water pumps have to be sized for safety valve set pressure, right?

 

[metengr]

This is a question you absolutely need to ask your local Jurisdiction or regulatory body that regulates/licenses boilers for operation. What we say here does not matter.

 

[Duwe6]

If you don't put anything onto the boiler not rated for 900psi, the answer is 'probably not'. Ask your insurance and/or state Authorized Inspector. That will be the answer that matters.

If you have added anything that is not rated up to 900 psi, the answer is 'Absolutly Yes, you must redo the PSV's'. Don't bother asking your Inspector.

Note that the body size of your 900# PSV's may be too small for the orifice required for proper capacity at 175#. May need completely new valves, unless you saved the old ones.

 

[littletoes]

The amount of Safety Valves is dependent on the heating surface area of the boiler, the burner size in comparison to boiler capacity, and one other item that slips my mind at this time....