Tank cleaning | comparing the available methods
After a large oil storage tank has been in service for a certain period, sludge and deposits gradually build up on the tank bottom. To support inspection and maintenance, a change of stored product or safe operation, tanks have to be cleaned periodically.
In the past, tank cleaning relied largely on personnel entering the tank and cleaning it manually. Today, as safety requirements and equipment technology continue to develop, mechanical cleaning, closed-loop circulation and reduced or no-man entry are becoming important directions for tank cleaning technology in China and internationally.
So what exactly are the differences between the various cleaning methods, and how far has mechanical cleaning developed?
1. Traditional manual tank cleaning: people enter the tank directly
Traditional manual cleaning normally requires the tank to be taken out of service, emptied, ventilated and gas tested, after which workers enter the tank to remove sludge, residues and deposits from the shell.
The process itself is relatively straightforward, but personnel spend long periods inside the confined space of the tank. That places high demands on gas testing, ventilation, explosion protection, personal protective equipment, on-site attendance and emergency rescue.
Manual cleaning is therefore not something that "cannot be done". The real issue is that once people enter the tank, the chain of risk controls becomes considerably longer.
2. Mechanical cleaning in China is no longer simply "machines replacing people"
In recent years a relatively clear standards and technology framework for mechanical cleaning of oil storage tanks has taken shape in China.
SY/T 6696-2025, Code of practice for mechanical cleaning of oil storage tanks, in force from 18 June 2026, specifically governs mechanical tank cleaning operations, while the current JB/T 13138-2017 sets the corresponding industry standard for tank cleaning equipment.
AQ 3042-2025, a mandatory work safety industry standard in force from 1 July 2026, goes further: for tanks with a capacity of not less than 1,000 m3 where mechanical cleaning is feasible, a mechanical cleaning method should be selected.
Mechanical cleaning usually does not mean simply lowering a nozzle into the tank. It uses suction, circulation, jet cleaning, oil-water separation, gas monitoring and other equipment and processes so that more of the cleaning work is carried out by machinery.
Engineering practice in China has also begun to move towards a closed "cleaning - inspection - recovery" workflow. A study of mechanical cleaning of large floating-roof crude oil tanks published in Petroleum Engineering Construction in 2025 reported that, in the actual project concerned, the cleaning cycle per tank was shortened by 20 days compared with the traditional manual approach, labour costs fell by 46.99% and overall costs fell by 27.59%.
3. A clear international direction: further reducing or eliminating tank entry
International standards likewise focus less on prescribing a particular type of equipment and more on controlling the risk created when personnel enter a tank.
The tank cleaning guidance of the U.S. Occupational Safety and Health Administration (OSHA) explicitly lists work activities such as removing remaining product and tank bottom material without entering the tank. API Standard 2015 manages entry and cleaning safety systematically across the whole process, from taking a tank out of service to returning it to service.
In commercial practice, several No-Man-Entry technology routes have already appeared in European and other markets, including remotely operated robots, high-pressure jetting, vacuum suction and closed-loop circulation cleaning systems.
4. Safety, efficiency and environmental management: where the methods really differ
Looking at manual cleaning, mechanical cleaning and the more advanced no-man-entry or closed-loop approaches side by side, the difference is not simply whether machinery is used.
Personnel exposure. Manual cleaning requires people to enter the tank. Mechanical cleaning lets equipment take on more of the cleaning work and so reduces the need for entry. Some robotic and no-man-entry solutions go further and separate personnel from the hazardous environment altogether.
Operational efficiency. Mechanical equipment can run circulation, suction and jetting continuously, and on some large tank projects this significantly shortens the cleaning cycle. The actual duration still depends on tank size, the properties of the medium, sludge thickness, internal structure and the final cleanliness required.
Management of residual oil and cleaning medium. Some mechanical, closed-loop systems carry out residual oil suction, oil-water separation and medium recycling during the cleaning process, so that cleaning and recovery form a more complete process chain.
Environmental management. Reducing long periods of open operation and collecting cleaning media and by-products centrally helps to control vapour emissions and waste generation during the work. Whether environmental compliance is achieved, however, ultimately depends on the actual process, vapour control and waste disposal management as a whole.
5. How should a cleaning method be selected?
In practice, no single solution suits every tank.
The choice of cleaning method should take account of tank capacity and structure, the stored medium, the condition of bottom deposits, the out-of-service window, safety risk, whether personnel will later need to enter for inspection, and the project budget.
Looking at standards and technology development in China and abroad, one trend is becoming increasingly clear: tank cleaning is shifting from "how to protect people once they are inside" towards "how to complete more of the work before anyone enters, and reduce entry altogether". Mechanisation and no-man-entry technology are developing along exactly this line.
Tecway Industrial | tank cleaning equipment rental and cleaning services
For periodic inspection and cleaning of storage tanks, Tecway Industrial can provide mechanical tank cleaning equipment for rental together with the associated cleaning services, with cleaning arrangements configured flexibly according to tank type, project schedule and site requirements.
For companies that do not need to own a complete cleaning package long term, the rental model reduces one-off equipment investment. At the same time, mechanical cleaning reduces the need for personnel to enter tanks for high-risk work, improving efficiency while better addressing safety management and project delivery requirements.
References
- Ministry of Emergency Management: AQ 3042-2025, Safety specification for cleaning operations of storage tanks in onshore oil and gas fields
- National Energy Administration / National Public Service Platform for Standards Information: SY/T 6696-2025, Code of practice for mechanical cleaning of oil storage tanks
- National Public Service Platform for Standards Information: JB/T 13138-2017, Cleaning equipment for oil storage tanks
- American Petroleum Institute: API Standard 2015, Requirements for Safe Entry and Cleaning of Petroleum Storage Tanks, Ninth Edition, 2024
- U.S. OSHA: Major Work Activities for Tank Cleaning Operations
- Petroleum Engineering Construction: Research and application of construction methods for mechanical cleaning of large floating-roof crude oil storage tanks, 2025
- Wolftank Austria: No-Man-Entry Tank Cleaning Project Case
About Tecway Industrial
Tecway Industrial Systems Ltd., formerly Tecway International (Petrochemical) Ltd., was established in Hong Kong in 1995; Beijing Tecway Xuyang Industrial Equipment Co., Ltd. is its registered subsidiary in Beijing.
Both companies are engaged in services related to the import of equipment for the oil and gas storage and transportation and petrochemical industries. As consultants and distributors, we carefully select and provide our customers with practical, high-quality and cost-effective solutions sourced from reputable suppliers worldwide.