Tank Cleaning · Accident Alert
During oil tank cleaning, the real danger is often not the sludge you can see, but the atmosphere inside the tank that you cannot see, cannot reliably smell and cannot judge from experience.
Oxygen deficiency and the accumulation of toxic or flammable gases can turn into an accident within moments of a worker entering the tank. And if people on site rush in to attempt a rescue without proper protection, the casualties can multiply.
01 How did a routine tank-cleaning job end in multiple fatalities?
In its July 2025 hazardous-chemicals accident alert, China's Ministry of Emergency Management (MEM) once again cited the "14 July" major poisoning accident at a company in Luoyang, Henan Province.
Outcome: 3 fatalities, 1 injured
Task: removing residue from the bottom of a storage tank
The direct cause was not complicated:
The workers entered the tank without analysing and testing the atmosphere inside, and without any safety protection.
Even more sobering, once the first worker was in distress, the on-site rescuers likewise entered the tank without the necessary protective measures, which is what turned a single casualty into multiple fatalities.
02 Inside a tank, "looks fine" does not mean safe
After long-term storage of crude oil, refined products or similar media, the tank bottom, shell and residues can create a complex gas environment.
Even after the liquid has been drained, oxygen deficiency and pockets of toxic or flammable gas may remain.
One of the defining features of this hazard is that human senses cannot assess it reliably.
The tank must never be judged safe to enter simply because:
- the manway is already open;
- the tank "does not smell too strong";
- the previous person went in and nothing seemed wrong.
The basic sequence for confined-space work: ventilate first, test second, work last.
MEM regulations also make clear that ventilation and gas-concentration monitoring must continue throughout the job; the moment an abnormality appears, personnel must be evacuated immediately.
For tank cleaning specifically, AQ 3042—2025 Safety Specification for Storage Tank Cleaning Operations at Onshore Oil and Gas Fields, in force since 1 July 2026, sets out further concrete requirements for pre-entry gas testing, monitoring during the work and personnel management.
03 Gas testing is not a one-off "check before entry"
A common misconception on site is that a passing pre-entry test means the whole job is safe.
In reality, the atmosphere inside a tank keeps changing as residues are disturbed, as cleaning progresses and as ventilation conditions vary.
Effective gas testing therefore has to run through the entire period that people are inside the tank.
AQ 3042—2025 requires gas testing to be carried out as specified before anyone enters a tank, and the tank atmosphere to be monitored continuously while work is under way.
When planning tank-cleaning work, operators should therefore also ask:
- Is the testing carried out at the right time?
- Are the sampling points sensible?
- Is monitoring maintained throughout the job?
- When an alarm sounds, does work actually stop and are people actually withdrawn?
The purpose of gas testing is not to tick a box in the records; it is to detect changes in the tank atmosphere early enough to get people out.
04 After an incident, the most dangerous move may be "go in and save them now"
Many confined-space accidents share a painful pattern:
Only one person is initially in distress, but co-workers instinctively enter the space to help, and the result is multiple casualties.
The Office of the State Council Work Safety Committee has issued a dedicated circular on such cases, noting that several confined-space accidents began with a single casualty, but escalated because rescuers entered without identifying the hazardous agent or taking reliable protective measures.
Rescue red line: no blind rescue attempts, ever.
"No blind rescue" does not mean standing by and doing nothing.
The correct response is to activate the site emergency plan immediately and, once the hazardous agent has been identified and safety measures such as respiratory protection and rescue equipment are in place, to have properly equipped and qualified personnel carry out a controlled rescue.
The current Provisions on Work Safety in Confined Spaces for Industrial and Trading Enterprises likewise require that rescue after an accident be carried out in a controlled, scientific manner, and that the attendant must stop any blind rescue attempt made without adequate safety measures.
This is one of the most important, and most easily overlooked, lessons in confined-space training.
05 Reducing tank entry is itself a key risk-control strategy
Looking at what these accidents reveal, most of the severe consequences ultimately occur at one step: people entering the tank.
For tanks where it is feasible, completing more of the cleaning mechanically and reducing the need for personnel to enter a high-risk environment is therefore an option that deserves increasing weight when operators plan tank-cleaning work.
AQ 3042—2025: tanks with a capacity of 1,000 m³ or more that are suitable for mechanical cleaning shall be cleaned mechanically.
Mechanisation is no excuse to relax safety management, but it offers a different approach to risk control:
Rather than relying entirely on protecting people once they are already inside the tank, reduce their exposure to confined-space hazards at source, through the choice of working method itself, wherever conditions allow.
Tecway Industrial | Oil tank cleaning equipment rental and cleaning services
For scheduled tank inspection, maintenance and cleaning, Tecway Industrial offers rental of mechanised oil tank cleaning equipment together with associated cleaning services, with cleaning solutions configured to the tank type, project schedule and site requirements.
For operators that do not need to own a complete cleaning system long term, the rental model reduces one-off capital outlay. At the same time, mechanised cleaning reduces the need for personnel to enter tanks for high-risk work, improving efficiency while striking a better balance between safety management and project delivery.
References
- Ministry of Emergency Management: Hazardous Chemical Accidents That Occurred in July in Past Years (July 2025)
- Ministry of Emergency Management: AQ 3042—2025 Safety Specification for Storage Tank Cleaning Operations at Onshore Oil and Gas Fields
- Ministry of Emergency Management: Provisions on Work Safety in Confined Spaces for Industrial and Trading Enterprises
- Ministry of Emergency Management: Interpretation of the Provisions on Work Safety in Confined Spaces for Industrial and Trading Enterprises
- Office of the State Council Work Safety Committee: Circular on Recent Accidents in Which Improper Rescue Led to Increased Casualties
About Tecway Industrial
Tecway Industrial Systems Limited, formerly Tecway International (Petrochemical) Limited, was established in Hong Kong in 1995. Beijing Tecway Xuyang Industrial Equipment Co., Ltd. is its subsidiary registered in Beijing.
Tecway Industrial Systems Limited and Beijing Tecway Xuyang Industrial Equipment Co., Ltd. specialise 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 feasible, high-quality and cost-effective solutions for our customers, sourced from reputable suppliers around the world.