Horizontal cylindrical single and double-walled tanks for underground storage of flammable and non-flammable liquids. Made by using shell plates and dished ends made in carbon steel type S235JR complying with UNI EN 10025.
The external shell is welded by submerged arc welding procedure while the internal part is MIG-welded. Parts are designed in compliance with rules and regulations in force.
Single-walled tanks form an impermeable containment; they act as the inner tank of double-walled tanks.
Double-walled tanks; for these tanks, a secondary wall is welded around the inner tank, which forms an impermeable self-contained tank. These tanks are provided with two sockets for the leak detection system in order to permanently monitor the integrity of the tank.
All tanks are hydraulically tested. Tests are pressure tests and are performed to check the inner tank and the interstitial space between the inner and the outer tanks as well.
EXTERNAL COATINGS:
Each tank is provided with an external protection coating which also acts as cathodic protection. The external coating of each tank undergoes a high-voltage test in order to prove its integrity.
POLYURETHANE: steel plates are sandblasted (SA 2.5 - ISO 8501-1) and coated with a type-868.06 grey polyurethane resin, applied hot, which consists in a polyurethane-made, 2-component, solvent-free coating meeting the NFE 86-900, DIN 6607 and DIN 4681 Part 3 standards. This coating is a seamless protective film offering high tensile strength. Together with the excellent mechanical and chemical resistance of the material, it guarantees the best-in-class level of protection against external agents and a better preservation of the underground tank.
EPOXY-TAR: coated externally with epoxy-tar paint consisting in an epoxy-based, 2-component product made with epoxy resins modified by a coal tar-based hydrocarbon resin.
FIBERGLASS (GRP): steel plates are sandblasted (SA 2.5 - ISO 8501-1) and coated externally with a reinforced fiber-glass coating.
INTERNAL COATINGS:
When an internal coating is required, tank's inner surface is prepared in accordance with the customer's requirement and the coating manufacturers specifications to ensure permanent adhesion of the selected coating. On request we can provide the following internal surface coating:
1. Internal coating for non-drinking water: steel surface is sandblasted (SA 2.5 - ISO 8501-1) and coated with an anticorrosive layer of epoxy-based two-components resin.
2. Internal coating for drinking water: steel surface is sandblasted (SA 2.5 - ISO 8501-1) and coated with a bicomponent polyammine epoxy coating which is certified by the Ministry of Health for prolonged contact with drinking water and food.
3. Internal coating for aviation fuels: steel surface is sandblasted (SA 2.5 - ISO 8501-1) and coated with a light coloured epoxy-phenolic resin free from zinc, cadmium and copper alloys.
Underground Tanks on pictures: