Tank cleaning process and services

This is a quick demonstration of Oreco's BLABO® system performing a safe, environmental friendly tank cleaning and oil recovery process. This demonstration covers a floating roof tank containing crude oil, but the process varies depending on oil type and tank size.

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The BLABO® system is installed according to the mobilisation plan approved by the customer. The mobilisation process involves the installation of the Suction, Recirculation, Separation and Skimming modules. The time required for mobilisation of the BLABO® system and the auxiliary equipment varies depending on the complexity of the job, but usually it does not take longer than a week.

The auxiliary equipment are set up in accordance with prevailling regulations regarding potentially hazardous zones. The colours red, yellow and green illustrate the different safety zones. The zones are set up to meet the highest international safety standards and directives when working in potentially hazardous environments.

Depending on the diameter of the tank, the required number of nozzles are installed in the roof. This is either done through existing openings or new, cold-tapped openings securely made with the certified SafeTap® tool. The nozzles are key to ensuring an optimal cleaning result. Their unique indexed washing pattern fully covers the complete surface of the tank.

Tank blanketing

To secure a safe tank cleaning process an inert gas, typically nitrogen, is injected into the tank. The purpose is to reduce the oxygen level to below 8 per cent to eliminate the risk of explosion. This oxygen level is held under the entire cleaning process


Desludging is the first process in the cleaning of the tank and this is where most of the oily sludge from the tank is removed. The desluding process may begin when the oxygen level has fallen below 8 per cent. The nozzles are operated one at a time, alternating between all of the nozzles supplied with the system. Since the sludge may contain solids, water and trapped, liquefied oil it may be necessary to add cutter stock to re-liquefy the sludge. 

Tank cleaning services

The tank cleaning service process consist of an oil wash and if required a final hot water wash. Oreco's efficient and especially designed Single Nozzle Sweepers (SNS)® are installed on the roof of the tank and play a vital part in the cleaning process.The nozzles use recirculated oil as their primary cleaning media and their effeciency is due to their far-reaching, low pressure high impact jets. The nozzles are hydraulically driven and two nozzles at a time can be operated. 

Via a PLC in the Recirculation module the nozzles can be programmed to focus on areas that require more intensive desludging. The non-man entry concept of the BLABO® system means that personnel do not enter the tank during cleaning. The system is easily operated and monitored by a few trained operaters via built-in PLCs and user friendly control panels.

Safety and protection of personnel during tank cleaning services are of high importance. The BLABO® system is a non-man entry system, since there is no need for personnel to enter the tank during the process. Every component of the BLABO® system has been designed with safety and human health in mind. In addtion to this, personnel must undergo a comprehensive training programme in operating the BLABO® system and in safety procedures.

Oil separation

The Separation module enables tank owners to achieve specific separation requirements. Separation takes place simultaneously with desluding and the sludge is separated into clean oil, solids and water. 

The decanter in the Separation module performs a liquid/solids separation, while the high speed separator makes a oil/water separation of the liquid. The BLABO® system recovers close to 100 per cent of the hydrocarbons. This continues untill the tank is free from sludge. The clean oil is pumped to the pipeline and can be reused.

Water wash

At this stage there is no sludge left in the tank. To clean the tank completely a final water wash is necessary and this is where the Skimming module comes into action. 

The nozzles spray fresh water into the tank and hereafter the water is pumped through the Skimming module where coalescing plates perform the oil/water separation.The oil is skimmed off the water surface and pumped back to the tank owner as recovered oil, and the water is pumped directly to local waste water treatment facilities.


Finally demobilisation and de-installation of the tank cleaning system takes place. As soon as the tank atmosphere has been approved by a safety officer, personnel are free to enter. 

Equipment, piping and cabling are disconnected, de-mounted, cleaned, packed and loaded onto trucks. For easy transportation the BLABO® system is built into standard 20' high cube containers.

Click to view a detailed animation of the entire tank cleaning process in Windows Media Player.

Contact us to find out more about automated tank cleaning and tank cleaning services or to get your own copy of our multimedia CD-ROM.

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Welcome to Oreco A/S

Oreco A/S has acquired the company Entecx Environmental Technologies ApS. With the acquisition Oreco consolidates and further advances its position as world-leader and preferred supplier of Automated Tank Cleaning and Oil Separation Technologies to the global oil and gas industry.

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