Flexible Polyvinyl Chloride (PVC) Secondary Containment Liners are more commonly used in the liquid fertilizer industry to satisfy many state secondary containment requirements for aboveground storage tanks. Most secondary containment methods serve as catch containers and only come in contact with the product when it leaks from the tank. A flexible PVC internal tank liner works differently and has added benefits beyond simply satisfying containment requirements.
Tank Liners are Primary Containment
PVC tank liners are situated inside the aboveground storage tank as opposed to most other secondary containment methods that are outside of the tank. Because the tank liner is what holds the product in the tank, the PVC liner acts as the primary containment, and the tank becomes the secondary containment. This design is permitted by many states as long as the tank liner system has leak monitoring capabilities incorporated into the design.
Logistical strategies must be implemented in using a flexible tank liner to ensure the material stands up to the product and the its metal tank housing. With the tank liner serving as primary containment, the product must be compatible with the PVC. Care must also be taken when filling or cleaning the liner to ensure no sharp objects are introduced into the liner.
Most flexible PVC tank liners are suspended from the top of the tank below the roof rafters and have connections to the nozzles and manways that are integrated with the liner to make it an entire tank system. In addition to the liner itself, the tank is equipped with valve boxes with leak monitor ports to ensure the product is contained should an inlet or outlet valve leak or break.
Extra Benefits of PVC Liners
The two main benefits of using a PVC tank liner are potential longer tank life and lower cost for required containment. The life span of a tank in part depends on how long the shell material and welds are effected over time by exposure to product stored, the weather, and water. Using a PVC liner creates a barrier between the potentially corrosive liquid product and the tank shell and floor. This decreased exposure to liquid and corrosive products can increase the life of a tank.
The second benefit of a PVC tank liner is that it is less expensive than other secondary containment methods. Using a double walled tank is purest form of secondary containment by having a tank within a tank. However, it also comes with a much higher price tag due to it requiring double the steel to build. A lined dike is the next choice in price, but it also has added cost due to it requiring a significant amount of land beyond the size of the tank and the operational cost of disposing of rainwater that collects in the dike. Several states now require all dike liquids be agronomically applied. The internal flexible PVC liner is the best choice because the material is much less expensive than steel, does not require additional land, or have additional operational costs.
To learn more about the benefits of an internal PVC tank liner and whether it meets your state’s containment requirements, contact us at Heartland Tank Services, Inc.