One natural event that could potentially lead to catastrophic risk, resulting in a complete failure of a chemical storage tank system, is an earthquake. Earthquakes can happen in areas not considered earthquake zone, such as the August, 2011 5.8 magnitude tremor that rocked Virginia.
Considering the risk of an earthquake on a chemical storage tank, a proper restraint system is essential. Let’s explore steps to take to protect your chemical storage tank in the event of an earthquake.
Evaluate the Earthquake Risk
It’s vital to determine the possibility of a seismic event at the specific location of the polyethylene chemical storage tank. Poly Processing uses the latest International Building Code to design restraint systems for polyethylene plastic storage tanks. The actual location and seismic activity are evaluated to make sure safety is ensured.
How Do Polyethylene Tanks React in a Seismic Event
Fiberglass tanks are more rigid and brittle than polyethylene tanks and therefore can’t absorb higher seismic and wind forces. Polyethylene is more ductile, absorbing the forces and stresses during a seismic event. As a result, the risk of damage to the polyethylene chemical storage tank is less than a steel or fiberglass tank.
How a Seismic Tank Restraint System Is Designed
The size of the polyethylene storage tank, the weight of the fluid, and the type of chemical being stored will determine the restraint system required to prevent damage to the tank during an earthquake. Passive stainless or galvanized steel clips, separate from the polyethylene tank design are used. These clips confine the tank to the area during an earthquake.
Fiberglass tanks, typically with the clips molded into the tank design, work as long as material structure of the fiberglass tank isn’t compromised. Damage to these structural components can be difficult or impossible to detect on fiberglass chemical storage tanks.
Inspection of seismic restraints is simplified with polyethylene tanks since the restraints are separate from the tank and made of steel. It’s important to visually inspect the steel tank clips and any cables and anchor bolts for corrosion to make sure the restraint system will be effective if it’s needed.
During the 1989 Loma Prieta earthquake in California, over 100 Poly Processing polyethylene storage tanks were located in the earthquake zone. None of the tanks failed. However, while the tanks and seismic restraints held up to the quake, pipes fitted to the tanks cracked and were damaged due to the effect of tank movement on inflexible fittings. Consider flexible tank fittings to help reduce the risk of failure in the complete chemical storage system.
Designing a separate restraint system that functions independently from the tank is the solution to preventing catastrophic storage tank failure in the event of an earthquake.