Natural Gas safety valves

[Sam654]

I need to replace a 3/4 x 1" safety valve on a natural gas main that has a missing label. The only question I have is what the seat material should be. Metal, Buna, Viton? Is there a standard dictating this?

 

[bimr]

Probably no specific standard for the seat material. Are you interested in an automatic valve?

Here is a typical specification for a safety valve at a facility:

Gas safety shut-off valves shall be FM & UL listed, electric motor operated, normally closed, manual reset type. Valves shall be rising stem design with a straight through flow path with metal-to-metal seat and disc arrangement. The valve seat shall be stainless steel and the disc ductile iron. Valves shall be provided with a NEMA 4 enclosure modified for Class I, Division II hazardous locations, be provided with an electrical terminal block and shall operate on 120 V AC., 60 Cycles, single phase. Valves shall meet ANSI Class VI leakage standard and shall be provided with a visual indicator to note the position of the valve whether "OPEN" or "SHUT".

Gas safety shut-off valves 2 inches and smaller shall be threaded, 2 1/2 inches and larger shall be flanged. Flanged valves shall be provided with companion flange set by valve manufacturer.

1. Gas safety shut-off valves 2 inches and smaller a. Manufacturer: 1) Maxon Corporation Series 808. 2) Or Approved Equal.

 

[Sam654]

Thanks bimr. This is a run of the mill safety relief like a Kunkle or similar, not a Maxon. There is no standard at the facility. I was considering whether I needed bubble tight shutoff (Buna N) or integrity in the event of fire (metal seats). I was being a bit lazy not going through all the NFPA or ASME/APi standards.

 

[Latexman]

Google and download Parker's o-ring handbook. That will have material of construction ratings for NG. It has a listing of UL Approved Services for NG.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.