Anti-corrosion coating system for the inner wall of crude oil tanks – lower surface of the floating deck and side walls of the floating deck

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GB50393-2008 specifies the use of an oil-resistant, electrostatic dissipative coating with a thickness of not less than 250μm (with a surface resistivity of 108Ω–1011Ω). On the other hand, the \"China Coatings Industry Association Industry Standard CNCIA-HG/T0001-2006 ‘Specifications for the Application and Acceptance of Antistatic and Corrosion-Resistant Coatings on Oil Storage Tanks’\", which represents another viewpoint, suggests that oil-resistant antistatic coatings with a thickness of not less than 350 microns (and a surface resistivity of 105Ω–109Ω) should be used. Clearly, the differences between these two viewpoints lie in the coating thickness and surface resistivity. The choice of paint types remains the same. Given that this area is always in direct contact with the oil in the upper part, and since corrosive substances such as water tend to accumulate at the bottom of the tank, corrosion of the oil in this area is relatively mild. A coating thickness of 250μm should be sufficient. During painting operations inside tanks, using roller brushes on the top surface is very difficult (for safety reasons, spraying is hardly used for painting inside tanks these days). Currently, the design uses epoxy oil-resistant antistatic coatings with a high solid content; there are also designs that employ solvent-free epoxy antistatic coatings. The most common coating defect in this area is interlayer delamination, for the following reason: when the humidity inside the tank is high, dew formation is likely on the surface of this area, which affects the adhesion between the coating and the substrate as well as between successive coating layers. Oil-resistant coatings are usually thermosetting coatings with a high cross-linking density, and there must be a maximum interval between applications. If coating is applied beyond this maximum interval without sanding, it becomes difficult to ensure adhesion between the layers. In my opinion, using solvent-free epoxy antistatic coatings is more beneficial for safety; if applied in a single coat via high-pressure airless spraying, it will not cause issues with interlayer adhesion.