7 replies to this topic

[Graduate process ENG]

All,
I am involving on selecting place that can be used to bring new propane storage tank used for gas plant processing, therefore, I am looking for standard procedure used to select suitable or safe location for propane storage tank that should be away from Hazard and associated risk.

Your respond will be high appreciated.

Thanks,
Graduate Process Eng

[breizh]

let you consider this resource , it may help you :

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

Breizh

[Graduate process ENG]

Thanks

[ankur2061]

Graduate Process ENG,

I would recommend that you get hold of API STD 2510 - Design and Construction of LPG installations where there are clear guidelines related to installation of LPG tanks considering the hazard risks of fire and explosion. There is a section devoted to 'Siting Requirements and Spill Containment' in the standard.

Hope this helps.

Regards,
Ankur

[kkala]

This is understood to be a layout issue. Required safety distances of the propane storage from factory fence, other equipment, units, or roads should be respected. These safety distances are usually included in legislation, can differ to some extent from country to country and a simple example can be found at http://www.npchse.ne...PS/C-sf-550.pdf.
In the past a layout respecting safety distances would be approved by authorities, unless environmental nuisance was possible to nearby communities. It can be valid even now in a few cases. But safety distances can be often considered as a rule of thumb now. Present trend is to show to authorities that the layout is safe enough through a proper safety study; see http://www.hse.gov.u...easplantlay.htm. Thus risk of any major accident originating from propane storage (e.g. fireball, gas explosion), or even originating from neighboring equipment but causing potential damage to propane storage, should be assessed. Final layout should induce risks within acceptable level (*), then it is considered safe.
An brief example of such assessment for LPG spheres can be found at http://www.oknation....t.php?id=563728. I have seen a wider version of this "analysis" / risk assessment in the Web ~3 years ago, but cannot find it now. Today requirements would be stricter, clarifying for each event: probability of the event (as a number), areas to be potentially destroyed, estimated fatalities / injuries. Of course this also depends on what data is demanded by local authorities.
Authorities may take much care of some points, and neglect others; the latter should be treated by the engineers having undertaken the Project.
Above will suggest "how far" propane storage should be, depending on size and kind of storage (bullet, sphere, refrigerating). As I have seen here, LPG bullets do not require so long safety distances as spheres.
Of course adequately safe engineering design withing the installation (isolation valves, fire fighting systems, codes, etc) is necessary (but not concerning the query). Simple event probabilities met in risk assessment books are based on this assumption. Reduced probability of internal accident, means reduced probability of domino effects on affected external areas.
(*) Risk is extent of damage combined with probability of event to occur.

Edited by kkala, 03 December 2011 - 12:52 PM.

[ankur2061]

Some API 2510 siting guidelines for siting LPG tanks:

The minimum horizontal distance between the shells of pressurized LPG tanks or between the shell of a pressurized LPG tank and the shell of any other pressurized hazardous or flammable storage tank shall be as follows:
a. Between two spheres, between two vertical vessels, or between a sphere and a vertical vessel, 5 ft or half of the diameter of the larger vessel, whichever is greater.
b. Between two horizontal vessels, or between a horizontal vessel and a sphere or vertical vessel, 5 ft or three quarters of the diameter of the larger vessel, whichever is greater.

The minimum horizontal distance between the shell of a pressurized LPG tank and the shell of any other nonpressurized hazardous or flammable storage tank shall be the largest of the following with the exception noted after Item d:
a. If the other storage is refrigerated, three quarters of the greater diameter.
b. If the other storage is in atmospheric tanks and is designed to contain material with a flash point of 100 deg F or less, one diameter of the larger tank.
c. If the other storage is in atmospheric tanks and is designed to contain material with a flash point greater than 100 deg F, half the diameter of the larger tank.
d. 100 ft.
The minimum horizontal distance between shells need not exceed 200 ft.

The minimum horizontal distance between the shell of an LPG tank and a regularly occupied building shall be as follows:
a. If the building is used for the control of the storage facility, 50 ft.
b. If the building is used solely for other purposes (unrelated to control of the storage facility), 100 ft.

The minimum horizontal distance between the shell of an LPG tank and facilities or equipment not covered as given above shall be as follows:
a. For process vessels, 50 ft.
b. For fllares or other equipment containing exposed flames, 100 ft.
c. For other fired equipment, including process furnaces and utility boilers, 50 ft.
d. For rotating equipment, 50 ft; except for pumps taking suction from the LPG tanks, 10 ft.
e. For overhead power transmission lines and electric substations, 50 ft. In addition, siting shall be such that a break in the overhead lines shall not cause the exposed ends to fall on any vessel or equipment.
f. For loading and unloading facilities for trucks and railcars, 50 ft.
g. For navigable waterways, docks, and piers, 100 ft.
h. For stationary internal combustion engines, 50 ft.

The minimum horizontal distance between the shell of an LPG tank and the edge of a spill containment area for flammable or combustible liquid storage tanks shall be 10 ft.


Regards,
Ankur.

Edited by ankur2061, 03 December 2011 - 11:08 PM.

[breizhonek]

If you intend to place this equipment in Europe, check current SEVESO 2 EEC directives, and future SEVESO 3 applicable in 2015.

Regards
BZH

[kkala]

If you intend to plac ethis equipment in Europe, check current SEVESO 2 EEC directives, and future SEVESO 3 applicable in 2015. Regards BZH

Indeed, the "safety study" reported in kkala's post of 3 Dec 11 is application of the Seveso 2 Directive. The "safety distances" still have value, but do not ensure a safe layout without indicating so in the "safety" (or Sevezo II) study. Same must be valid nowadays all over the world, but confirmation / advise would be appreciated. Techniques to assess events of pool fire, fire ball (BLEVE), explosion, etc, have been developed mainly in USA; they must be applied there. I quickly read once in web that after the accident of ...(?) safety distances (alone) are not enough, but I cannot find the web reference. Of course this is applicable here. Safety distances are legal requirements, yet approval of the plant requires submission to authorities of this "safety" study, which can be commented by them (see brief example of LPG spheres in mentioned kkala's post)

Edited by kkala, 07 December 2011 - 03:39 AM.