Storage Tanks & Pressure Vessels
Cleaning & Technical Inspection of Tanks
Cleaning & Technical Inspection of Tanks

A) Cleaning mechanized of tanks and waste recycling


Tanks that are used for the storage of crude oil, light and dark products will over time accumulate sediments (deposits or “dregs”) in their lower sections. Excessive build-up of deposits reduces the usable volume of the tank and increases abrasive wear and pollution of process equipment at the storage facility.

Sisaco has developed capacities for cleaning of vertical steel tanks from bottom and wall sediments using appropriate chemical cleaning equipment, which can be applied self-contained and enables mechanized cleaning.

 Sisaco can boast of a solid experience in the sphere of provision of services and chemical solutions for oil and gas industry, and can offer a modern and responsible approach to the problem of bottom deposits removal from the tank.
To remove bottom deposits, a mobile treatment complex of the 6th generation МКО-1000.3 is used.

Stages of tank cleaning technological process:

  - Preparatory works;
  - Removal of technological residue of oil products;
  - Preliminary degassing of the tank;
  - Washing and cleaning the internal surfaces of the tank;
  - Degassing of the gas space of the tank up to the sanitary norms;
  - Removal and processing of the bottom deposits;
  - Final cleaning of internal surfaces and general visual inspection of bottom and walls.
After removal of the technological residue of oil products, the tank is washed with technological detergent by means of a tank-washing machine MTM-ЧM.
Jet pressure ensures penetration of washing fluid into the surface layer of the oil product, without splashes, that may become charged with static electricity when bounce off the surface. Jet pressure at the machine nozzle output is 10 atmospheres. The jet is 25-30 meters long. Productivity and the number of washing cycles depend on the level of contamination and the group of oil product by viscosity.
To pump out the detergent from the tank together with the residue of oil products and oil slurries, a membrane or slurry pump is used.
Having entered MKO, the emulsion is undergoing the following treatment and separation stages:
1) The emulsion pumped out from the tank passes through the coarse filter, installed in front of the membrane pump, where large-scale mechanical impurities are separated, and is transferred to the cascade gravitation collector of solid particles, where the basic mass of solid particles is being separated from the emulsion and pumped into special tank for further disposal.
2) Further, the emulsion is transferred to the hydraulic cyclone where light fractions of solid particles are separated.
3) After the hydraulic cyclone the emulsion passes through the surge tank and enters the labyrinth of a tank of technical detergent МКО-1000, where the technical detergent is separated from the oil product. The water is combined with water solution of technical detergent, and the oil product, due to high demulsifying ability of the technical detergent, is separated from the emulsion and is transferred to the tank for oil products.
The essence of the technology lies in the regeneration of the detergent by means of the emulsion phase division into:
- hydrocarbon compounds,
- water solution with technical detergent, and
- mechanical solids.
The hydrocarbon compounds that have been formed are transferred further to be used in the technological process, the water solution with technical detergent is sent to a repeated cycle of tank cleaning, and the mechanical solids are disposed.
Specifications of consumable materials, resources for cleaning of bottom sediments of typical РВС-20 000 m3 with internal diameter 47.4 m.
The period for installation of mobile treatment complex at the site and readiness for operation is 4 hours.
Clean oil piping from the bottom sediments in the amount of 353 m3 takes about 10 hours (provided pump delivery 37 m3/hour).
Washout, pumping-out and phase separation of oil sludge takes not more than 35 hours (provided pump delivery not more than 10 m3/hour).
The period for washing, degassing, visual inspection and final cleaning in the shielded areas of the tank is 16 hours.

The total time for cleaning the tank with internal diameter 39.9 m is 60 hours or 8 working days (provided 8-hour working day).



  • Cleaning of types the tanks made of steel, concrete having aluminum and floating roof
  • protecting the environment due to lack of need to interment of waste and deposits
  • Reduce of costs (less consumption of water and chemicals, quick return of tank to operation, etc.)
  • High speed cleaning (the time it takes to clean a tank of 20,000 cubic meters (with volume of sediment 353 cubic meters) is 66 hours or 9 Shift)
  • Close of the cycle of cleaning, recycling and reuse of used chemical solutions
  • The lowest rate risk due to the presence of personnel inside the tank
  • Back products useful to the 98%
  • highest safety against fire and explosion due to work in a neutral space


Technological detergent (ТМС) used for operation is a low-hazardous substance of the 4th class of hazard (the lowest hazard class).


B) High Pressure Water Jet

Sisaco possesses wide experience of work with this method and offers cleaning for the following Tank equipment:

* Column equipment (oil refineries, petrochemical plants etc.),

* Soaking reactors (in visbreakers),

* Reactors (PVC, ABS, polystyrene)

* Traps and separators (manufacture of polyethylene and polypropylene),

* Tanks, vessels, railway tanks.


 Cleaning of reactor from formaldehyde resin


C) Inspection of Tank bottom

The inspection technology allows to control condition of the tank bottom even with heating tubes. work productivity is 400 m2 per one 12 hour shift. all defects are immediately detected which excludes necessity to specify the kind and scope of defect with other control methods.


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