Guidance on Flare Locations

[SEWConsults]

Does anyone know what codes govern the location of elevated, industrial flares? I see a minimum of 200 ft from process equipment a lot of places but no references.

Thanks for the help,
Shannon

 

[pennpiper]

I have looked through the list of NFPA Codes and Standards and I found no reference to Flare Stacks.
Here are the ones I found on the list that appear to relate to Refinery installations in one way or another.
NFPA 30 Flammable and Combustible Liquids Code
NFPA 59A Standard for the Production, Storage, and Handling of Liquefied Natural Gas (LNG)
NFPA 214 Standard on Water-Cooling Towers
NFPA 274 Standard Test Method to Evaluate Fire Performance Characteristics of Pipe Insulation
NFPA 275 Standard Method of Fire Tests for the Evaluation of Thermal Barriers Used Over Foam Plastic Insulation
NFPA 307 Standard for the Construction and Fire Protection of Marine Terminals, Piers, and Wharves
NFPA 326 Standard for the Safeguarding of Tanks and Containers for Entry, Cleaning, or Repair
NFPA 400 Hazardous Materials Code
NFPA 820 Standard for Fire Protection in Waste Water Treatment and Collection Facilities

To purchase a NFPA Code go here:

http://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asp

Based on my experience: Get it (the Flare Stack) as far away from everything as you can. That means anything inside the fence (Property line), outside the fence and the fence itself.
On one project I located the Flare on an island in the middle of the Storm Water retention Pond. The island was connected to the shore by a causeway that carried the pipeway, piping and a maintenance access road. The Flare KO Drum was on shore before the causeway.

prognosis: Lead or Lag

 

[LittleInch]

I always thought this was based on human thermal exposure limits - can't remember what they are, but you can do it in w/m2 and then analyse the flare radiation so that at full flow with the wind in that direction, no one would suffer from burns when standing at the perimeter fence.

The same thing applies to trees or wooden buildings needing to be a certain distance away.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[25362]

Visiting the following threads may be practical:

thread124-157384
thread124-40177
thread127-280575
thread798-88372
thread507-304499
thread809-190303

 

[SNORGY]

The flare radiation sfe exposure and distance guidelines are in API-521 / ISO 23251, Section 6.4 (in particular, Table 9).

You also usually need a blackened zone of 2.0 to 2.5 times the stack hight around the base of the flare.

 

[racookpe1978]

I have only been "observer" at refinery, not design team, so please QA this, but it appears that "blackened zone" would preclude grass or brush (wildlife or greenery zone) under the flare area, right? Sand, gravel, rock, concrete, or dirt OK, but not asphalt. No parking lot or other pipes or tanks too, right? If a cooling tower were next to the pond, then it would have to be checked for the walls of the tower getting too hot as well it would appear.

 

[SNORGY]

Yes. Blackened zone would be a zone clear of stuff that would catch fire. It's probably a term we see more often on rural sites to define the extent of grass and brush and tree clearing.