essenwood
Chemical
- Mar 6, 2003
- 25
Hi everyone,
Petroleum tank rim seal fires attributed to lightning are known to happen, fortunately, the statistics are rare.
Key strategy for preventing fire is to properly bond the roof and wall of the FRT via shunt, walkway ladder, cable.
Reasons such 1)seals become worn, cracked and/or damaged over time 2)tank shell becomes warped and out-of-round due to repeated filling, draining, heating, cooling, etc.
3)tank shell's inner surface becoming uneven from corrosion and/or petroleum residue can lead to a a situation where flammable vapor can exist around the rim edge of the tank. Thus area above the roof of a FRT is classified as a Class I Division I hazardous area.
My question is : does anyone know of any specifications on the amount of hydrocarbon % LEL that the operator of the FRT can expect in the VAPOR SPACE BETWEEN THE PRIMARY AND SECONDARY SEAL?
My tank caught fire the other day due to ligtning strike. The debate is whether: one should expect that there will always be hydrocarbon in the vapor space between the primary and secondary seal that is rich enough to catch fire and thus any fault in the bond between the roof and the wall would result in a fire even if the secondary seal is doing an excellent job in sealing the vapor from the open environment.Bascially, what I am alluding to is that even if my secondary seal is ok, there will always be flammable vapor in the space between the primary and secondary seals and if my shunts are not working properly, I still would have a fire to fight. Is this correct?
Thanks....
Petroleum tank rim seal fires attributed to lightning are known to happen, fortunately, the statistics are rare.
Key strategy for preventing fire is to properly bond the roof and wall of the FRT via shunt, walkway ladder, cable.
Reasons such 1)seals become worn, cracked and/or damaged over time 2)tank shell becomes warped and out-of-round due to repeated filling, draining, heating, cooling, etc.
3)tank shell's inner surface becoming uneven from corrosion and/or petroleum residue can lead to a a situation where flammable vapor can exist around the rim edge of the tank. Thus area above the roof of a FRT is classified as a Class I Division I hazardous area.
My question is : does anyone know of any specifications on the amount of hydrocarbon % LEL that the operator of the FRT can expect in the VAPOR SPACE BETWEEN THE PRIMARY AND SECONDARY SEAL?
My tank caught fire the other day due to ligtning strike. The debate is whether: one should expect that there will always be hydrocarbon in the vapor space between the primary and secondary seal that is rich enough to catch fire and thus any fault in the bond between the roof and the wall would result in a fire even if the secondary seal is doing an excellent job in sealing the vapor from the open environment.Bascially, what I am alluding to is that even if my secondary seal is ok, there will always be flammable vapor in the space between the primary and secondary seals and if my shunts are not working properly, I still would have a fire to fight. Is this correct?
Thanks....
