Ensuring Safety: HSE’s Warning on Misclassification of Thermite

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The  UK Health and Safety Executive (HSE), recently issued a safety notice highlighting the incorrect classification of thermite and articles containing thermite. This new advisory underscores the importance of proper classification, labelling and transportation of hazardous materials to reduce risks and ensure the safety of individuals and the environment.

Thermites, substances known for their highly flammable properties, are too often being classified and labelled incorrectly in Great Britain and the ADR area. Despite meeting the criteria for classification as Class 1 dangerous goods, which includes explosive substances and articles, thermites are often mistakenly categorised as Class 4.1 dangerous goods (flammable solids), non-dangerous goods or

The consequences of misclassifying these goods are significant. Failure to accurately classify thermite and thermite-containing articles can lead to the inadequate communication of hazards to individuals working throughout the transport chain and emergency services. In the event of a transport incident, this lack of awareness about the true nature of the materials can pose serious risks to responders and surrounding communities.

Moreover, incorrect classification undermines the implementation of necessary safeguards during the manufacturing and storage of thermites. These safeguards are essential for protecting both people and the environment from potential harm.

Duty holders are reminded of their responsibility and it is imperative that they take immediate action to rectify this issue. Thermites and thermite-containing articles must not be consigned or accepted for carriage by road or rail without undergoing the appropriate classification process.

What is thermite, and why is it important to classify and label it correctly?


Thermite is a mixture of aluminium powder (a reducing agent) and a metal oxide (usually iron) that produces a very high temperature on combustion.  When ignited, a thermite process occurs where the reducing agent steals oxygen from the metal oxide, producing intense heat and molten metal as a result. This reaction can reach temperatures of up to 4500°F (2500°C), making it an incredibly powerful source of energy.

The Thermite Process is the method of obtaining liquid metal by reduction of the oxide with aluminium powder, when ignited with magnesium ribbon it reacts by producing iron and aluminium oxide at an intensely high temperature. The oxygen atoms separate from the metal oxide and attach to the aluminum atoms as aluminum forms stronger bonds with oxygen than iron. The products of the reaction are a stable aluminium oxide, iron (or other metal) oxide, and a large amount of heat.  This reaction involves simultaneous oxidation and reduction processes – the reducing agent steals oxygen from the metal oxide, producing intense heat and molten metal as a result.  When ignited, the reducing agent steals oxygen from the metal oxide, producing intense heat and molten metal as a result.

One of the primary applications of thermite is in welding rails. Its ability to generate intense heat makes it suitable for joining metal components, particularly in railway construction and repair. It is also used in the manufacture of incendiary bombs.


This HSE’s notice serves as a reminder of the importance of accurate classification labelling and transportation of hazardous materials. By adhering to proper protocols and ensuring compliance with regulatory requirements, duty holders play a crucial role in promoting safety and minimising risks associated with the transport of hazardous goods.

View the HSE Report.

Download “Guidance on the manufacture, storage and carriage of thermites and termite containing articles”.