Hazardous Chemicals in ISO Tanks: What Goes Wrong, and How Kricon Group Prevents It

By Jakub Makarewicz, Dangerous Goods Safety Adviser, and Juri Udre, Commercial Director, Kricon Group · Published 04.10.2026 · Reading time: 11 minutes

Why are hazardous chemicals dangerous to transport?

Hazardous chemicals are dangerous to transport because they can burn, poison, corrode or react, and a transport chain exposes them to heat, movement, delays and human error. A product that is perfectly stable in a temperature-controlled plant can behave very differently after two weeks in a tank container on a hot terminal or in the hold of a ship.

For the bulk liquids we move every day in ISO tanks, the main hazards are:

• Flammability (Class 3) – solvents and many intermediates give off vapours that ignite easily. A small leak in an enclosed hold can create an explosive atmosphere.
• Toxicity (Class 6.1) – products such as chloroform harm people through inhalation or skin contact, even in small quantities.
• Corrosivity (Class 8) – acids and alkalis attack tank linings, gaskets, valves and neighbouring cargo if the wrong equipment is used.
• Reactivity and self-heating – monomers and organic peroxides can polymerise or decompose on their own if temperature limits are exceeded or stabilisers run out. This releases heat, which speeds up the reaction until the tank fails.
• Pressure – liquefied gases and heated cargo build up internal pressure, so the tank’s design pressure, relief valves and filling ratio must match the product exactly.

On top of the chemistry sits the logistics risk. Every hand-over – from producer to haulier, terminal, shipping line, port of transhipment and final consignee – is a moment where information can be lost. That is why so many incidents begin with a piece of paper, not a valve.

Are ISO tank containers safe for hazardous chemicals?

Yes – when the right tank is used, properly maintained and correctly documented. An ISO tank container is a stainless steel pressure vessel inside a 20-foot frame, built to the UN portable tank standards in the IMDG Code (sea) and ADR/RID (road and rail). Each tank carries a T-code, such as T11, that defines which products it may carry, its test pressure and its required fittings.

Tanks must pass an intermediate inspection and test every 2.5 years and a full periodic inspection, including a hydraulic pressure test, every 5 years. Compared with drums or IBCs, a tank container means fewer packages, fewer handling operations and a much stronger shell.

But the incident record shows that a strong tank is not enough. The six cases below are among the most serious dangerous-goods incidents involving containerised chemicals in recent years. Each one teaches a lesson that applies directly to how ISO tank cargo should be handled.

The worst dangerous goods incidents of recent years – and what caused them

1. MSC Flaminia (2012): the case that redefined responsibility for tank container operators

On 14 July 2012, the container ship MSC Flaminia suffered an explosion and fire in the mid-Atlantic on a voyage from Charleston to Antwerp. Three crew members died. The source was divinylbenzene (DVB) carried in tank containers. The product underwent a runaway auto-polymerisation – a self-accelerating reaction that generated enough heat and pressure to explode.

At the time, DVB was shipped under a generic Class 9 (“miscellaneous”) entry. After the casualty it was reclassified as a Class 4.1 polymerising substance (UN 3532), and the IMDG Code now requires it to travel under temperature control. In 2018, a US federal court found the shipper 55% and the tank container operator 45% strictly liable, and cleared the shipowner and carrier. Industry commentators drew a clear message for tank operators: meeting the legal minimum is not enough when you know – or should know – more about the product’s real behaviour.

Lesson: classification is the starting point, not the end of the risk assessment. Temperature-sensitive and inhibited products need active control of temperature, stabiliser levels and time in transit, whatever their regulatory class.

2. Maersk Honam (2018): when a “low-risk” class hides a high-risk product

On 6 March 2018, fire broke out in a forward cargo hold of the Maersk Honam in the Arabian Sea. Five crew members lost their lives. Singapore’s Transport Safety Investigation Bureau concluded in 2020 that the fire most likely began in a cargo of sodium dichloroisocyanurate dihydrate (SDID), a chemical used in bleaches and pool disinfectants.

SDID was carried as Class 9 (miscellaneous dangerous goods), even though its decomposition behaviour resembles more hazardous Class 5.1 oxidisers. The investigators also found that the fire alarm was not raised at the outset and that ventilation was not closed quickly enough, allowing toxic smoke to spread.

Lesson: the regulatory class does not always capture the real hazard. Experienced dangerous goods professionals look beyond the label to the Safety Data Sheet and the product’s known behaviour.

3. X-Press Pearl (2021): a known leak that nobody stopped

On 11 May 2021, the crew of the X-Press Pearl found a container of nitric acid leaking on board. Requests to discharge the container were refused at Hamad Port in Qatar and again at Hazira in India, both citing a lack of specialist facilities. On 20 May, off Colombo, fire broke out. The ship burned for days and sank on 2 June.

No lives were lost, but the environmental damage was enormous. The UN described it as the largest recorded plastic spill, with an estimated 70–75 billion plastic pellets released along Sri Lanka’s coast. In July 2025, Sri Lanka’s Supreme Court ordered the operator and its local agent to pay US$1 billion in compensation.

Lesson: a leak is an emergency, not an inconvenience. Correct packaging and compatibility checks prevent leaks, and a clear escalation plan makes sure one is handled before it becomes a disaster.

4. Aqaba chlorine release (2022): the failure happened on the quay

On 27 June 2022, at the port of Aqaba in Jordan, a pressurised tank holding around 25 tonnes of chlorine fell while being loaded onto a ship and ruptured. A toxic cloud spread across the port. Thirteen people died and 265 were injured.

The official investigation found that the wire-rope sling used was rated for only 8.5 tonnes, yet it had been used to lift several far heavier tanks before it finally broke. The investigation also found that senior officials had delegated critical safety tasks to untrained personnel. The port’s director general and other officials were dismissed.

Lesson: safety does not end when the tank leaves the filling station. Handling equipment, lifting procedures and the competence of everyone in the chain matter as much as the tank itself.

5. YM Mobility (2024): a temperature-controlled cargo without temperature control

On 9 August 2024, a container exploded on board the YM Mobility at Ningbo, China. The blast threw six containers overboard and destroyed three others. China’s Maritime Safety Administration found that the cargo was tert-butyl perbenzoate, an organic peroxide that must be kept cool. It was in a reefer container that had been unplugged in summer heat. The product self-heated until it reached thermal runaway. Fortunately, the crew were evacuated without injury.

Lesson: temperature limits must be known, communicated and monitored at every stage – including during waiting time at terminals and transhipment ports.

6. Wan Hai 503 (2025): undeclared cargo, deadly consequences

On 9 June 2025, an explosion and fire tore through the Wan Hai 503 about 70 nautical miles off the coast of Kerala, India. Four crew members were reported missing and several of the 18 rescued suffered severe burns. The ship carried 157 containers of declared hazardous cargo. Indian officials said they believed undeclared explosives triggered the first explosion, which then ignited the flammable cargo around it.

Lesson: one dishonest or careless declaration puts the whole ship, its crew and every other shipper’s cargo at risk. Accurate declaration is the foundation of dangerous goods safety.

Summary: six incidents, one pattern

Incident	Year	Cargo involved	Root cause	Human cost
MSC Flaminia	2012	Divinylbenzene in tank containers	Runaway polymerisation; hazard under-classified	3 dead
Maersk Honam	2018	SDID (pool chemical)	Classification gap; delayed response	5 dead
X-Press Pearl	2021	Nitric acid	Leak not resolved; fire	No deaths; major pollution
Aqaba port	2022	Chlorine (pressurised tank)	Under-rated lifting gear; untrained staff	13 dead, 265 injured
YM Mobility	2024	Organic peroxide	Temperature control lost	No injuries
Wan Hai 503	2025	Mixed DG; suspected undeclared explosives	Suspected misdeclaration	4 missing

The five root causes behind chemical transport disasters

Across these and many smaller incidents, investigators keep finding the same five failures:

1. Misdeclared or undeclared cargo. The World Shipping Council estimates that misdeclared cargo accounts for around a quarter of cargo-related incidents. Wrong information means wrong stowage, wrong segregation and wrong emergency response.
2. Classification that misses the real hazard. As MSC Flaminia and Maersk Honam showed, a product can be legally classified yet still behave far more dangerously than its class suggests.
3. Lost control of temperature, stabilisers or time. Reactive products have a safe window. Delays at terminals, heat and missing inhibitor data close that window fast.
4. Equipment and handling failures. Expired test dates, the wrong T-code, worn gaskets or valves, poor cleaning and unsuitable lifting gear all turn a safe cargo into a dangerous one.
5. People and procedures. Untrained staff, unclear responsibilities and slow alarms appear in almost every investigation report. Rules only work when the people applying them understand why they exist.

How Kricon Group keeps hazardous ISO tank cargo safe

As an ISO tank operator with our own liquid bulk logistics operation, trucking division and cleaning and depot services, we control more links in the chain than a traditional forwarder. Our safety approach is built around the five root causes above.

A certified Dangerous Goods Safety Adviser oversees every hazardous shipment

Our certified DGSA is responsible for dangerous goods compliance across the company. Before a new hazardous product is accepted, the DGSA reviews its classification, UN number, packing group and Safety Data Sheet, and confirms that the proposed tank type, T-code and route are suitable. We follow the lesson of MSC Flaminia: we look at how the product really behaves, not only at its legal class. Where a product is temperature-sensitive or inhibited, we agree the limits with the shipper before booking.

ADR- and IMDG-trained people at every desk that touches dangerous goods

Investigations repeatedly point to untrained clerical and operational staff accepting incorrect information. At Kricon Group, staff who book, document or handle dangerous goods are trained under ADR and the IMDG Code and receive regular refresher training. That includes the IMDG Code Amendment 42-24, mandatory since 1 January 2026. Booking and documentation teams are trained to spot inconsistencies between a declaration, the Safety Data Sheet and the requested equipment – and to stop a shipment until they are resolved.

A strict tank inspection and testing regime

Every tank in our fleet is tracked against its 2.5-year intermediate and 5-year periodic inspection dates. A tank approaching its test expiry is not offered for a hazardous load. Before each loading, tanks go through pre-loading checks covering the shell, valves, gaskets, pressure-relief devices, manlid seals and the absence of residues. Every tank must also have a valid cleaning document from the previous cargo. Equipment is matched to the product’s required T-code and material compatibility – for example, our 20ft T11 and 23ft T11 tanks for a wide range of chemicals.

Certified management systems: ISO 9001:2015 and SQAS

Our quality management system is certified to ISO 9001:2015, which means our procedures are documented, followed and independently audited. We are also assessed under SQAS, the European chemical industry’s own assessment system for logistics providers, run by Cefic. SQAS looks specifically at safety, security, quality and environmental performance. For a chemical producer, an SQAS assessment gives an independent, comparable view of how a logistics partner actually operates.

Clear responsibilities and documentation

The MSC Flaminia judgment showed that, after an incident, what matters is what you can prove. We keep complete records of product approval, tank inspection status, cleaning history and the documents issued for every shipment. This protects our customers as well as us.

Checklist: how to choose a safe ISO tank partner for hazardous chemicals

If you are responsible for chemical logistics, these are the questions we recommend asking any tank operator or forwarder – including us:

• Do you have a certified DGSA, and do they review new hazardous products before acceptance?
• Are your booking, documentation and operations staff trained under ADR and the IMDG Code, and how often is training refreshed?
• How do you track tank test dates, and what happens to a tank close to expiry?
• What pre-loading checks are carried out, and can you show the cleaning document from the previous cargo?
• How do you handle temperature-sensitive or inhibited products, including waiting time at terminals?
• Which certifications and assessments do you hold – for example ISO 9001 and SQAS – and can you share the results?
• What is your emergency procedure if a tank leaks during transport?

Safety is a shared responsibility. As a shipper, the most valuable things you can provide are an accurate declaration, a current Safety Data Sheet and clear information on temperature, stabiliser and transit-time limits.

Frequently asked questions

Are ISO tank containers safe for hazardous chemicals?

Yes. ISO tank containers are built to the UN portable tank standards in the IMDG Code and ADR/RID, use pressure-rated stainless steel shells, and are periodically inspected and pressure tested. Most serious incidents are caused not by the tank itself but by process failures: misdeclared cargo, wrong tank type, missed temperature or inhibitor requirements, poor handling and slow emergency response.

What causes most container ship fires?

Cargo-related fires are frequently linked to dangerous goods that are misdeclared, undeclared or incorrectly classified. The World Shipping Council, citing Allianz data, reports that a container ship fire breaks out roughly every 17 days and that misdeclared cargo accounts for around a quarter of cargo-related incidents.

How often must an ISO tank be inspected and tested?

Under the IMDG Code and ADR/RID, a portable tank needs an intermediate inspection and test every 2.5 years and a full periodic inspection, including a hydraulic pressure test, every 5 years. Exceptional inspections are required after damage or repair. A tank with an expired test date must not be filled.

What does a DGSA do in chemical logistics?

A Dangerous Goods Safety Adviser (DGSA) is a certified specialist who oversees a company’s compliance with dangerous goods regulations. The DGSA checks classification and documentation, advises on packaging and tank selection, trains staff, investigates incidents and reports annually on the company’s dangerous goods activities.

What is SQAS and why does it matter for shippers?

SQAS (Safety and Quality Assessment for Sustainability) is the European chemical industry’s assessment system, run by Cefic, for logistics service providers. It evaluates safety, security, quality, environmental and CSR performance using a standard questionnaire and independent assessors, so chemical producers can compare logistics partners on a common basis.

How can shippers reduce the risk of a dangerous goods incident?

Declare cargo accurately and completely, share the full Safety Data Sheet, flag temperature, inhibitor and transit-time limits, and work with a logistics partner that has a DGSA, trained ADR/IMDG staff, documented tank inspection and cleaning controls, and recognised certifications such as ISO 9001 and SQAS.

Work with a tank partner that takes dangerous goods seriously

The incidents in this article were not bad luck. Each one followed a chain of small, preventable failures. At Kricon Group – Global Liquid Care – our job is to break that chain before it starts. If you are shipping hazardous chemicals in ISO tanks and want a partner whose DGSA, people and procedures are built for it, contact our team or email info@kricon.net.