Repairing a polyethylene tank depends on factors such as the location of the leak, the age of the tank and the chemical it is storing, but sidewall leaks generally require cutting away the damage and replacing it with a patch. Technicians can often repair leaks around fittings by replacing the fitting or gasket. Heat welding these tanks is usually not successful as it affects the structure of the polyethylene.
In order to repair sidewall cracks, the technician specifically designs the patch to fit the contours of the sidewall and attaches it mechanically, typically using a blind flange patch. If the blind flange is not appropriate, the tank may require a custom patch design. In most instances, professionals are able to repair cracks up to 1 foot in length.
The cause of the damage to the tank is also a factor in determining the appropriate repair. Technicians are generally more confident in repairs to damage from a known source, such as the tines of a forklift, than cracks that appear for no apparent reason. Tanks that suffer damage from heat, pressure or storing chemicals such as sulfuric acid are often more difficult to repair. If a company has used the tank for several years, it might be at the end of its useful life cycle.