NFPA 54 Applicable?

[millerbp]

I have a project in which gas is produced in a large lagoon-type digester (similar to a landfill). The gas piping from the digester is HDPE (below ground) and then stubs above ground. The gas in the pipe is low pressure (sometimes slight vacuum).

Does NFPA 54 apply in this situation? If so this means that the above ground piping need to be metallic, correct? Safety, of course, is the primary concern but if it has to be metallic it will go to SS because of the H2S.

I've seen multiple installations for landfill gas collection in which they snake HDPE above ground all the way to the collection/processing facility.

 

[bimr]

NFPA 820 Standard for Fire Protection in Wastewater Treatment and Collection Facilities would apply.

"Gas-Handling Equipment. Equipment, including gas compressors, sediment traps, drip traps, gas scrubbers, and pressure-regulating and control valves, used in the removal of gas evolved from the anaerobic digestion process and the compression, conditioning, or treatment of such gas. Gas-handling equipment does not include equipment or devices for the utilization of the gas, such as boilers, engines, and waste gas burners."

 

[millerbp]

I believe my treatment system is expempted from 820 under 1.1.3.1 and 1.1.3.2. What spec do landill collection systems use?

 

[bimr]

The reference numbers 1.1.3.1 and 1.1.3.2 seem to be incorrect. Are you referring to onsite treatment systems?

What type of business do you operate?

 

[millerbp]

The reference numbers were for:
1.1.3(2)On-site treatment system (commercial establishment) and

1.1.3(1) Treated waste is not discharged to a publically or privately operated municipal facility.

I'm not sure how "small" commercial establishment is defined, but 1.1.3(1) is a definite. The sytem is a "packaged" plant (consisting of multiple interconnected skids). The effluent is discharged or reused onsite. the entire system is also located outdoors.

 

[bimr]

In order to be effective, the NFPA Standards would have to be adopted by the jurisdiction where your project is located, as part of the building code.

So if you want to determine the standard that you must follow, you should contact the local building code department.

In addition, if not adopted in the building code, the NFPA Standards are only voluntary guidelines.

The NFPA prepares the various standards in response to hazardous historical accidents. Tombstone engineering more or less.

Lacking a better NFPA standard and/or not being an expert regarding the potential for hazardous operations, one would be advised to follow the guidelines in the NFPA 820 for any type of wastewater treatment plant, not just municipal treatment plants.

I believe that the NFPA 54 is the standard for fuel piping. Fuel piping is normallly metallic for safety in case of fire, where the fire could potentially burn through the piping. Digester piping would not be covered by NFPA 54 and it is completely acceptable to use non-metallic piping. There is probably no NFPA standard for digester gas collection. The digester gas may not even be flammable.

 

[millerbp]

That is basically my thoughts. There's no doubt we want as safe a system as possible, but we also don't want to incur unneeded costs. Let me assure you that digester gas is flammable.

Also, I spoke with some technical experts at the Plastic Pipe Institute and they indicated that this is a very common application.

Thanks.