In diesel oil tanks, the most common problem is water accumulated at the bottom, coming from condensation and from refueling itself. Water promotes the formation of sludge at the tank bottom, which contaminates the fuel, clogs filters and accelerates internal corrosion.
Cleaning removes the remaining diesel, free water and accumulated sludge, followed by washing of the internal surfaces. The oily residue is collected and disposed of with full traceability. In supply tanks for generators and fleets, periodic cleaning preserves fuel quality and the reliability of the equipment that depends on it.
BPF fuel oil (low pour point heavy fuel oil) is viscous at ambient temperature. In BPF tanks, dense sludge builds up at the bottom and does not flow with ordinary pumping. For this reason, cleaning starts by heating the product with saturated steam, which reduces viscosity and allows the recoverable oil to be transferred to another tank.
After the transfer, the remaining sludge is removed by suction, manual or mechanized removal and high-pressure hydroblasting. Steam is also used for tank inerting when hot work or decommissioning is involved. For an overview of the service, see industrial tank cleaning.
Oil and fuel tanks store flammable and combustible products, so cleaning follows NR-20 (Brazilian regulation for flammables and combustibles), which covers safety in handling these products, as well as NR-33 (Brazilian regulation for confined spaces) for tank entry, since the tank is a confined space. In practice, this means control of ignition sources, atmosphere monitoring before and during entry, ventilation and an entry permit. For diesel tanks at generators, fleets and bases, see fuel tank cleaning.
Because sediment, sludge, particles, oxidation residue and water accumulate at the bottom, reduce useful volume and compromise fuel quality, in addition to promoting internal corrosion.
By pumping the remaining fuel into another reservoir. When the oil is viscous, it is heated with saturated steam to make pumping easier.
Manual removal of solids, high-pressure hydroblasting, mechanical cleaning of surfaces and suction of sludge and sediment.
It includes inerting the tank with saturated steam, which eliminates flammable vapors, before activities such as cutting the steel structures.