7 replies to this topic

[hamidkeng]

Dear ALL
In my country, Fire Zone study carry out with TOTAL GS 253, in order to find best distance between fire zones,
I want to be inform about your methods, or codes and standard,
What is your criteria?

[breizh]

Consider this link to support your studies:

http://www.hse.gov.u...easareaclas.htm

Hope this helps
Breizh

[demank]

Dear ALL
In my country, Fire Zone study carry out with TOTAL GS 253, in order to find best distance between fire zones,
I want to be inform about your methods, or codes and standard,
What is your criteria?

Dear Hamidkeng,
I think you mean not your country, but your COMPANY, right?
Commonly for me, we use Identification of Zone boundaries that consider of the geography of firewalls (if any), bundwall, decks and module levels, roadways, buildings, dikes, HVAC items, fire protection systems, etc.

But need confirm about fire zone,
do you mean fire zone for deluge system as per NFPA 13, NFPA 15, NFPA 16? where commonly one deluge is for one fire zone.
or do you mean zone on Hazardous Area Classification based on IP 15, API 500, API 505?

[hamidkeng]

Thanks all

Please note that Fire Zone is not related to Hazardous Area Classification, It is a area that can be independently isolate in the case of fire,

Generally a fire zone is a process unit (or sometime two or more unit which work near together)

The main issue is distance of fire zones. Total GS 253 recommend 4 main scenario to find distance between fire zones:

1- Jet fire (9.5 kw/m2) 2- Pool Fire (9.5 kw/m2) 3- Flammable Gas dispersion ( 1LFL) 4- Vapor Cloud Explosion (170 mbar).

Fire Zone is important for following issues:

F&G response (which section shutdown in response to Flame or Gas detection)?

Fire Water Demand Calculation (Fire Zone in fire)

Flare Blowdown load calculation

Shutdown Level (ESD1 is fire zone shutdown)

 

Edited by hamidkeng, 13 February 2013 - 01:12 PM.

[kkala]

Thanks for the information about Fire Zones, I had a vague picture on the subject: The plant (e.g. refinery) is separated in fire zones, each aiming at area of 500 m2 max (this can be eventually increased, if fire water, its drainage, etc, are sufficient for it). Fire fighting scenarios deal with one Fire Zone at a time. These Zones have a clear spacing of 20 ft wide on all sides, or provision of access ways (??).  In case of any fire in a Zone, fire water supply has to be adequate, as well as its drainage. Besides combined pressure relief due to fire has to be assured. Possibility of installing emergency isolation valves is examined for pipes crossing different Fire Zones. There may be also other provisions unknown to me.

'TOTAL GS 253' seems to have a more quantitative approach. Values in parentheses are understood to represent max acceptable values on the concerned Fire Zone from events in other (neighboring) Fire Zones; e.g. ground radiation up to 9.5 W/m2, if a Jet/Poll fire occurs in another Zone. Is it so?

Edited by kkala, 16 February 2013 - 02:23 PM.

[hamidkeng]

Thanks for the information about Fire Zones, I had a vague picture on the subject: The plant (e.g. refinery) is separated in fire zones, each aiming at area of 500 m2 max (this can be eventually increased, if fire water, its drainage, etc, are sufficient for it). Fire fighting scenarios deal with one Fire Zone at a time. These Zones have a clear spacing of 20 ft wide on all sides, or provision of access ways (??).  In case of any fire in a Zone, fire water supply has to be adequate, as well as its drainage. Besides combined pressure relief due to fire has to be assured. Possibility of installing emergency isolation valves is examined for pipes crossing different Fire Zones. There may be also other provisions unknown to me.

'TOTAL GS 253' seems to have a more quantitative approach. Values in parentheses are understood to represent max acceptable values on the concerned Fire Zone from events in other (neighboring) Fire Zones; e.g. ground radiation up to 9.5 W/m2, if a Jet/Poll fire occurs in another Zone. Is it so?

 

Thanks for your answer and sorry for my delay.

Don't mix up this fire zone with Fire area that we consider to calculate Fire case of PSVs.

Your criteria for fire zone area (500 m²), makes no sense for me. Please refer the code. I have seen units (or Fire Zone) with 66m*80m=5280m² area.

TOTAL GS 253 is a guide to establish Safety distances between fire zones. As I mentioned above, four main scenarios are considered for this safety distance:

1- Jet fire- Leak Size 20mm Criteria 9.5 kW/m²

2-Flammable Gas Dispersion- Leak Size 20mm Criteria 1LFL

3- Vapor Cloud Explosion, Half of congested area full of gas- Criteria 170mbar (200mbar in 2012 rev)

4- Pool Fire- Dike area in Fire Criteria 9.5 kW/m²

I think the results of TOTAL are very big! sometimes fire zone distance could be up to 120 m! (normally for slug catcher liquid part) and 80m for LPG/Propane/High pressure gas units.  

[demank]

Hello HamidKeng,

firezone distance up to 120 m is based on what scenario? If refer to Jet Fire/LFL Dispersion, have you checked the calculation especially at the leak size? the leak size for firezone calculation should be 20 mm refer to GS 253.

 

And then, the explanation from kkala is make sense for me.,

[hamidkeng]

Thanks for your reply

 

Please explain kkala points for me. I need more explanation and reference,

 

SLUG CATCHER scenario Liquid part is generally the worst scenario. I saw distances between 100 to 120m in different projects,

 

In my project a NGL plant this distance was 101m.

 

Pressure is 101barg, composition from C1-C6+ liquid, Leak size 20mm. Outcome LFL distpersion.

 

http://img.im/i/u1pig4

 

 

Bests

 

 

 

 

 

Hello HamidKeng,

firezone distance up to 120 m is based on what scenario? If refer to Jet Fire/LFL Dispersion, have you checked the calculation especially at the leak size? the leak size for firezone calculation should be 20 mm refer to GS 253.

 

And then, the explanation from kkala is make sense for me.,

Edited by hamidkeng, 31 March 2013 - 02:58 AM.