The chine is the flat steel plate at the bottom of steel tank that intersects and rest on a concrete pad, base or foundation.
Water infiltration is a general problem for storage tanks, as moisture and water penetrates below the steel bottom or floor plate, creating a corrosive issue. Due to movement and weathering, regular sealants such as silicones, polyurethanes, mastics, asphalts, bitumens, or bonding tapes have not proven to be effective, long term solutions. Some problems associated with the above referenced sealants are:
- UV Degradation
- Poor Adhesion
- Limited Flexibility
The floor plate of the tank is resting on concrete. A gap is common between the concrete base and the steel floor plate. If the chine area is not sealed, water can penetrate between the floor plate and the concrete base creating a corrosive environment. Under adverse conditions, such as those involving prolonged, unchecked exposure to air, moisture, condensation, chemicals, etc. the bottom plate projecting from the tank will corrode. If not prevented the corrosion will worsen and eventually cause leaking in the chine area as well as lead to possible section loss of the tank bottom. This leads to leakage, extensive repairs, lost production or even expensive tank replacement.
The concept is a simple one; stop corrosion in the crevice environment where a steel tank or vessel comes in contact with a concrete base or pad. You must seal between the concrete and tank itself.There is always moisture underneath a tank. When the tank chine area is sealed we are stopping the ingress of air. It is the air that combines with the moisture that accelerates corrosion. The Critical Zone of a tank is 18-inches in from the wall or shell on the tank bottom and 18-inches up from the floor on both inside and outside of the tank. Treating the tank chine area greatly reduces the corrosion that occurs there, thereby adding years of life to the tank.