Relief Valve required on Fuel Train?

[bh1]

I have conflicting information on the requirment for a Pressure Safety Relief valve on the natural gas supply line after the regulator and before the automatic fuel shut off valves. Does anyone know which code lists that requirment?
The piping between the reducing valve and the burner is specified at the same pressure requirment as the upstream line so it would not be to protect the line.

This is a forced draft, 200,000 lb/hr, gas fired package boiler.

 

[ApC2Kp]

bh1,
The piping is not the problem, as you point out it has same design as the upstream piping. The automatic fuel valves probably have a low pressure rating of maybe 15 psi, so that a relief valve is required in event of the pressure regulator failing open / not shutting off tight.
Remember to route the vent from pressure relief valve, and the vent from pressure regulator to a safe location, above burner and away from fan inlet.

 

[bh1]

What if my shut off valves are also rated above the supply line pressure.

Is there some code about relief valves being needed to limit the potential gas flow to a burner if the high gas pressure switch failed at the same time as the gas regulator?

 

[EGT01]

bh1,

Gas fired boilers are not my area of expertise but I do recall a discussion some time back about fuel gas supplies that you may find interesting.

See if these help...
thread794-104500
and the referenced link...

http://www.driedger.ca/ce5_fh/CE5_FH.html

 

[InTheField]

You will want to take a look at NFPA 85 (Boiler Combustion Systems Hazards Code) which lists the current standards (also check with the local jurisdiction).

Specifically in the NFPA take a look in Annex A and the figures that show typical fuel supply systems - then let your fingres do the walking to figure out what your system requires.

Cheers.