Anytime a chemical tank is located outside, it’s exposed to the elements, such as sun, wind, and rain. Special considerations are recommended to protect the life of the storage tank, especially from damaging ultraviolet rays from the sun in states like Texas, Arizona, Southern California, Nevada and even New Mexico and Colorado.
This article will explore solutions to protect outdoor polyethylene storage tanks from UV damage.
How Ultraviolet Exposure Affects Poly Storage Tanks
Extended exposure to sunlight radiation and in particular ultraviolet rays results in weathering of polyethylene storage tanks. Without proper treatment, the higher energy spectrum of the UV light causes a compound breakdown of the polyethylene elements, resulting in the polyethylene tank material becoming brittle. This can cause micro cracks leading to leaks and potential failure of the poly chemical storage tank. For additional information about the impact of ultraviolet light exposure on various resin colors, please refer to the Poly Processing test within the Technical Bulletins under Carbon Black & Plastics.
Solutions to Reduce the Risk of Polyethylene Tank Exposure to UV
Several solutions exist to minimize the potential of UV light when polyethylene storage tanks are stored outside.
- Carbon Black Resin - Carbon Black is a nearly pure, elemental carbon. When used as a resin in the molding of the polyethylene tank, it acts as an absorber of UV light. Adding Carbon Black is a simple, inexpensive solution to creating an internal stabilizer to the poly tank. When outside, the UV energy is absorbed, transformed into heat, and dissipated throughout the tank. While Carbon Black polyethylene tanks tend to have higher temperatures than lighter colored or white polyethylene tanks, the UV protection outweighs the effects of the increased temperatures. Carbon Black is the preferred pigment in higher-end applications, especially when storing harsh chemicals such as sodium hypochlorite.
- Paint the Tank - Painting the polyethylene tank also adds UV protection. An acrylic house paint, that expands and contracts with the tank, is recommended. Please refer to the Poly Processing Technical HowTo Bulletin on surface preparation for painting poly tanks.
- Insulation Coating and Paint - A thin layer of insulation to control heat absorption and a coat of acrylic paint is another solution to protect against UV ray damage to the poly storage tank.
Additional Considerations Regarding The Impact of UV on Polyethylene Tanks
The cycle times, how frequently the polyethylene tank is emptied and filled, and the number of sidewall fittings on the tank, increase the potential for leaks and tank failure. Microcracks will tend to form where the tank is the weakest, at the tank fittings.
One solution to minimize the number of sidewall fittings and reduce the potential for microcracks is Poly Processing’s Integrated Integrally Molded Flanged Outlet or IMFO® system. With IMFO® chemical storage tank solutions, the flange is molded into the tank itself, eliminating sidewall fittings.