4 replies to this topic

[Rodscott]

Hello forum members!

We will adapt two existing spheres, originally used to store 1,3 Butadiene, to store n-Hexane. These spheres will be pressurized with nitrogen blanketing.

My doubt is: is it necessary to foresse a diked area around these spheres storing n-Hexane?

Any help or advice will be very appreciated!

Thanks in advance!

Rodscott

Edited by Rodscott, 05 January 2013 - 06:53 AM.

[Dazzler]

Hi Rod
Dikes (or bunds) will be necessary if the flash point temperature of the stored liquid is such that should a major leak or spill occur, a liquid will remain on the ground for an appreciable time. So even if it is volatile, a bund may be necessary to hold the liquid until it slowly evaporates or is otherwise managed back into another storage location. Even for a volatile liquid in a bund it can subcool due to the vaporisation and can be covered with a foam to slow its vapour cloud formation further (useful whether flammable or toxic - ie chlorine). You will need to look through the relevant flammable liquid storage and handling standards or regulations for your locaiton.
Dazzler

[Rodscott]

Hi Dazzler

Thank you very much for your help.

I will have a look at some standards but i think it is better to foresee a bund for these spheres. It will be better has one if something wrong happens in the future!

Rod

[Neelakantan]

i understand, they are existing spheres; you were storing butadiene either as refrigerated liquid or as compressed gas; originally the storage would have come under toxic/hazardous chemical storage; i dont know if petroleum rules also apply in your place.

now that you are storing n-hexane with N2 for blanketing (why nitrogen? why not natural gas?); with nitrogen blanketing it will vented to atmosphere? is there a danger of spill due to overflow / over filling?

this type of storage will definitely come under fire and petroleum acts. any developing or developed country will ask for bunds incase of spill or leakage;

regards
neelakantan

[kkala]

A diked area has to be constructed around the two spheres to retain hexane content during an accident. This according to legislation in Greece and other countries. Required dike capacity has to be according to local law, for example see http://www.cheresources.com/invision/topic/16863-maximum-capacity-in-a-diked-enclosure concerning other countries.
It is noted that Greek legislation does not require dikes for pressurized LPG storage (only "direction" of spills to safe locations), but it does for any other storage of combustibles of flash point lower than 100 oC. Butadiene is like butane, so existing spheres may not have been in dikes so far. n-Hexane is liquid under atmospheric pressure (boiling point~68 oC, flash point=-26 oC, vapor pressure~405 mm Hg at 50 oC) and would be ideally stored in floating roof tanks. Dikes are required for stored hexane, irrespectively of the storage type.
Probably existing spheres will operate as atmospheric tanks (storing hexane) blanketed by nitrogen (pressurized?).
Legislation of other countries is expected to be similar.

Edited by kkala, 13 January 2013 - 06:53 AM.