Single or Double Jacket Tank
Material, thickness, diameter…three major points. Two parameters influence the choice of material for the tank : Is the chemical hazardous?. Does it need a double jacket?. For example, for storing water, no retention is required. For sulfuric acid or ferric chloride, a double jacket or double skin tank is imperative.
Storage tanks must be placed on a flat surface which does not deform under the load. Stockage & Systèmesrecommends that its customers pay close attention to the quality of support structures :
- Flatness tolerance: 5mm under a 3m ruler and 1mm under a 1m ruler
- Levelness tolerance (or slope precision) 1mm/m
Tanks with integrated retention (double jacket or double skin tanks) enable compact, autonomous installations. The installation requires just a concrete pad. For outside installations, flashing protects the retention tank and prevents rainwater from penetrating inside the tank.
Retention design rules
Retention can be designed in a double jacket construction (PEHD or PP, tank + integrated retention) or in concrete (concrete retention pit with tank installed inside or placed on a pad).
- In concrete or double jacket construction, it must have an available volume that can recover the entire volume of the full tank in the event it fails.
- If there are multiple single jacket tanks to be installed, the volume of the concrete retention pit must equal 50% of the total volume of the tanks or the volume of the largest tank.
An integrated PEHD or PPH retention tank or concrete retention basin must not in any case let the product escape in the event of a spill. Retention must be completely sealed and may not contain any orifices which can let the stored chemical flow in an uncontrolled manner.
Only chemicals of the same nature can be stored in the same retention (acids and bases separately)