Dear Experts, Our design specification does not require total internal shell wall of gasolene and lighter products tank to be coated. Only the bottom portion is lined (1st course). After 12 years of service, we found out that the middle courses are experiencing corrosion rates higher than anticipated particularly at areas where the floating roof is always located. Our concern with coating is that it might be scrapped off by the weather shield movements. Other light product tanks with floating roof are also showing similar symptoms/conditions. Has anyone experienced this and if so, can you share your mitigation eg. successful coating used? regards, Alani

Thanks Krish. I'll check the details of the weather shield design. I think it could be that the neoprene has hardened over the years and was not replaced much earlier.

Hi, Our experience is that corrosion is severe in the 3rd-6th shell of an Gasoline or MS tanks. The reason is - the product (gasoline) level is most likely to be in that height for most of the time. The repeated wetting & drying creates ideal condition for preferential corrosion. Our painting requirement for Gasoline / naphtha etc tanks changed after a Failure gasoline tanks in one of our Refineries in 1983. The shell ruptured vertically at 5th shell course. And yes, the secondary seal matters. Sometimes, the mechanical type secondary seal abrades the tank shell repeatedly, and even destroys the paint. We generally go for either HB epoxy paint system or Inorganic Zn Sillicate+HB epoxy paint sytem. And painting is done for full shell internal+bottom paltes. And in some places, even the floating roof internal surface (which is in contact with the product). 'Hope it helps regards