Has it already been out of service a long time" or WILL it be out of service a long time? To prepare it for long term out of service, I suggest using 'float-coat'--which is routinely used to protect overhead water tower tanks from rusting. The lanolin based waxy material 'floats' on the water surface , uniformly coating the tank walls and roof underside as the tank gets filled with water.

Keith's question is valid, if it is already deteriorating it needs to be sorted out first.

One assumes that as it is a floating roof tank that it is used to store hydrocarbons, in which case the tank must be gas free, thoroughly cleaned and resting on its legs in the "high" position and all surfaces wetted with gas oil.

Roof drains etc to be open and regularly checked so that no water accumulates. Manholes should be left partly open to ensure breathing during idle period.

Tank bottom to be checked regularly and water drained.

thanks for your comments..

it is a naphtha filled tank... it had been not in use for 2 years....

whether it is advice to fill with water.... kindly give your reply

regards

mani

I would not fill with water, I would wet all surfaces with gas oil after cleaning and repairing as said previously. Water is not a good preservative, but maybe you have some other reason to want to "float" the roof. (I am not a tank expert, but have been involved over the years).

SSM123,

A simple common sense idea to me is to wrap /cover the tank tight to avoid air and moisture contact with polythene sheet to avoid corrosion.

Make sure the tank is completely dry -close all manways and vents etc. - purge it with N2 - keep a little positive pressure with more N2. Possibly put a small heater inside it to keep the tank walls above the dew point. Edmund

Nice idea, but have you ever seen a floating roof tank?