Putting a internal floating roof tank into service and taking it out of service

[DAWN555]

We are putting our first internal floating roof tank into service. Does anyone have any guidance for whether we need to take special precautions for LEL in the upper section of the tank during initial fill. My understanding as as we fill it in order to float it off the legs the vapor will be pushed out a breather vent until the roof begins to fully float on the liquid. Once it it floating the double seals and large vent on the top will be sufficient to prevent LEL build up in the upper section. But I am concerned during the initial fill. The material is a hexane like material.

And in 3 years when we have to take it our of service for an internal inspection and set the roof on its legs by emptying it slowly, air will be drawn through a vacuum break into the section below the floating roof as we fully empty. Again I am concerned about LEL below the roof at that point.

The tank is grounded but is that enough. Trying think of commissioning and prepare for maintenance procedures

thanks

 

[LittleInch]

For IFR tanks you should always assume the whole internal volume is full of vapour which could easily be at LEL.

An IFR only reduces vapour emissions. It doesn't seal the internal vapour space.

If there isn't a spark potential then you should be OK, but your statement about preventing LEL is just plain wrong.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MJCronin]

Suggest that you re-post in the Storage Tank Forum .....

MJCronin
Sr. Process Engineer