natural gas generator fuel piping question

[antigfk]

We are planning to install a 1300kW natural gas generator set at our facility. The utility put a metering station on our premises. The pipe coming out of the ground is run to a pressure regulator. This regulator has a 4" pipe outlet and is set to 5 psig. After the regulator is the metering components and then a flange. We are planning to run a 4" steel pipe from this flange point to another point near the generator. Near the generator the pipe will end at another flange. We will go from this flange to the generator with some flexible corrguated pipe with SS braid.

Question: Do the areas surrounding the flanges and meters need to be considered Class I Div II Group D? Is 5 psig on a 4" pipe enough to meet the requirements of NEC 500, that is - flammable gas in sufficient quantities to produce an explosive or ignitable mixture in the event of a leak from the flanges and/or meters? I think it is, but our safety department is pushing back on me.

 

[muckusmc]

POCO around here (central NJ), require 48" spacing between gas and electrical devises - ie: gas and electric metering and switching.
For some reason this does not pertain to LV equipment. ie: phone, cable, alarms

 

[yucan2]

We are planning to install a 1300kW natural gas generator set at our facility. The utility put a metering station on our premises. The pipe coming out of the ground is run to a pressure regulator. This regulator has a 4" pipe outlet and is set to 5 psig. After the regulator is the metering components and then a flange. We are planning to run a 4" steel pipe from this flange point to another point near the generator. Near the generator the pipe will end at another flange. We will go from this flange to the generator with some flexible corrguated pipe with SS braid.

Question: Do the areas surrounding the flanges and meters need to be considered Class I Div II Group D? Is 5 psig on a 4" pipe enough to meet the requirements of NEC 500, that is - flammable gas in sufficient quantities to produce an explosive or ignitable mixture in the event of a leak from the flanges and/or meters? I think it is, but our safety department is pushing back on me.

What is your facility type?

Petroleum refineries, and gasoline storage and dispensing areas;
Dry cleaning plants where vapors from cleaning fluids can be present;
Spray finishing areas;
Aircraft hangars and fuel servicing areas; and
Utility gas plants, and operations involving storage and handling of liquified petroleum gas or natural gas.
All of these are Class I . . . gas or vapor . . . hazardous locations. All require special Class I hazardous location equipment.

However your AHJ may include or exclude other areas.

The size of the fuel supply line is immaterial.

 

[rbalex]

From NFPA 37-2010, Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines:

4.5.2 Engine rooms or other locations shall not be classified as hazardous locations as defined in Article 500 of NFPA 70, National Electrical Code, solely by reason of the engine fuel, lubricating oil, or hydraulic fluid.

This does not mean there is no reason for concern; simply that it isn't the turbine and its fuel.

I am assuming the fuel service line, regulator and meter system belongs to the utility. They have their own Classification and protection techniques and probably shouldn't concern you.

If there is nothing in the piping between the meter system and the turbine inlet, except the flanges, then it is still a closed piping system and doesn't need to be classified.