DSEAR Risk Assessments for Industrial Machinery Manufacturing

Get in touch if you answer yes to any of the following:

If your site grinds, machines, cuts, welds, coats, or heat-treats metal, you’re already creating the two conditions the DSEAR regulations (the Dangerous Substances and Explosive Atmospheres Regulations 2002, set out in detail in HSE’s Approved Code of Practice L138) exist to control: a flammable atmosphere and a source of ignition, in the same place, at the same time. The UK’s industrial machinery and mechanical engineering sector is one of manufacturing’s largest, and one of the most exposed to fire and explosion risk.

Metal grinding, machining, spray coating, and heat treatment all generate flammable atmospheres, whether that shows up as suspended metal dust, solvent vapour from a coating line, or an oil mist thrown off during quenching. Many machinery manufacturers don’t recognise these as DSEAR triggers, because the hazard doesn’t look like the ones in a chemical plant. It looks like routine production.

DSEAR applies to most activities on an industrial machinery manufacturing site where a material capable of combustion is present. That includes:

• Use of flammable solvents and liquids (acetone, ethanol, toluene)
• Handling or storing flammable gases (LPG, hydrogen, methane)
• Metal grinding, machining, cutting, and finishing that generates combustible metal dust (aluminium, magnesium, titanium)
• Spray painting, powder coating, and paint-booth operations using flammable substances
• Hot works such as welding or grinding near flammable materials
• Chemical mixing or reactive processes that release heat or vapours
• Heat-treatment furnaces, ovens, and quench tanks using oils or flammable atmospheres
• Storing or handling flammable waste, such as solvent-soaked rags
• Filling or dispensing flammable liquids or gases from drums or cylinders
• Handling or transferring combustible metal powders, including feedstock for additive manufacturing

If any of these run at your site, you’re legally required to carry out a DSEAR risk assessment focused on the specific activities involving your dangerous substances. If your site stores dangerous substances above COMAH (Control of Major Accident Hazards) threshold quantities, you’ll likely have additional duties that sit alongside, and go further than, your DSEAR requirements.

Routine processes on a machinery manufacturing floor, grinding, machining, polishing, cutting, and finishing metal, generate fine metal dust as a by-product. Where that dust is aluminium, magnesium, or titanium, it’s combustible, and the finer the particle, the more readily it ignites and the more severely it burns. When enough dust is suspended in air and meets an ignition source, a spark, a hot surface, an electrostatic discharge, you get a dust explosion, not a fire.

The difficulty is that metal dust accumulates gradually and out of sight: on beams, ledges, extraction ductwork, and inside dust-collection systems. A small primary ignition can disturb these accumulations, throwing up a larger suspended cloud and triggering a far more destructive secondary explosion.

Workplace example: In October 2003, an aluminium dust explosion tore through the Hayes Lemmerz aluminium wheel plant in Huntington, Indiana. Fine dust thrown off by machining aluminium wheels had built up in the scrap re-melt and dust-collection system. When it ignited, one worker was killed and six more were injured. The US Chemical Safety Board found the company had never identified or controlled the hazard of its own aluminium dust, and that following the recognised standard for combustible metals would have prevented it.

You can’t judge the combustion behaviour of a metal dust by looking at it. You have to test it and establish properties such as minimum ignition energy (MIE) and explosion severity (Kst), so you can set an appropriate basis of safety for each dust-generating process. Sigma-HSE’s ISO/IEC 17025 accredited laboratory carries out this testing to the relevant standards, with the fastest turnaround time in the UK, giving you the data your DSEAR assessment needs.

If your site handles or transfers combustible metal powders, aluminium, magnesium, or titanium feedstock for additive manufacturing or 3D printing, you’re working with some of the most reactive materials DSEAR covers. Fine powder handled in bulk during loading, sieving, or reclaim behaves differently to the same metal in solid form or even in coarser machining swarf. Particle size, moisture content, and how the powder is handled between print runs all change the risk picture, and each needs testing on the specific material you use, not a generic assumption based on the base metal.

This is a newer risk for many machinery manufacturers moving into additive processes, and it’s often missed in a workplace risk assessment written for conventional machining, because the equipment and the workflow look nothing alike.

Q: Does DSEAR apply to your industrial machinery manufacturing operations?

A: Yes-if there’s a chance of a flammable atmosphere forming, even briefly. Industrial machine manufacturing operations that store flammable or combustible materials, or operate equipment that could ignite them, fall within the scope of DSEAR.

Spray painting, powder coating, and paint-booth operations using flammable coatings are a standard part of finishing on a machinery manufacturing line, and a standard DSEAR trigger. Flammable coatings, thinners, and cleaning solvents create the same combination of flammable atmosphere and ignition source as any other DSEAR-regulated process. Booth extraction, bonding, and earthing need to be part of your basis of safety from the start, not an afterthought once the booth is installed.

DSEAR applies to how your materials are used, stored, or processed, not just to their labelled properties. Diesel, for example, is classified as flammable under the Classification, Packaging and Labelling (CLP) Regulations, with a flashpoint around 55°C. At ambient temperature, a flammable atmosphere won’t form. Heat it above its flashpoint, as happens in some heat-treatment processes, and DSEAR applies. Flashpoint testing can be carried out by Sigma-HSE to confirm where that threshold sits for your specific fluid.

The same logic applies to quench oils and metalworking fluids. They can be stable at rest, but a fine mist, or oil heated above its flashpoint during machining or heat treatment, becomes a fire and explosion risk. Think about DSEAR in terms of the specific situation your materials are in on your site, instead of their properties on a safety data sheet.

Once you know where flammable atmospheres can form on your site, you need to classify those areas. DSEAR Regulation 7 makes a Hazardous Area Classification (HAC) a specific legal requirement, not an optional extra. If your DSEAR risk assessment report doesn’t contain one, that’s worth sending back to your provider.

For a machinery manufacturing site, this usually means classifying zones around grinding cells, dust-collection systems, and paint booths specifically, rather than treating the whole shop floor as one uniform area. Our Hazardous Area Classification guide covers how the zones work and which equipment category each one allows.

Once zones are classified, every piece of equipment placed in them needs to be rated to avoid becoming a source of ignition. Depending on the zone, that’s either specialist ATEX-rated equipment (rated for safe use in explosive atmospheres) or standard equipment placed appropriately. This covers all of your manufacturing equipment as well as fixtures, fittings, tools, and personal devices such as mobile phones.

Equipment gets updated often on a manufacturing site as processes evolve. When equipment changes, or hazardous zones change, your DSEAR assessment needs reviewing and reissuing by a competent person.

When you add a process, a new grinding cell, a powder-coating booth, a switch to a different cutting fluid, the DSEAR basis of safety needs reviewing before it goes live.

DSEAR Regulation 5 states that no new work activity involving a dangerous substance can commence unless an assessment has been made and the measures required by the regulations have been implemented. A full review is standard every three to five years, but review sooner after a near miss, or after any change to your process, however minor it seems at the time.

This gets harder to manage consistently once you’re running more than one site. We recently completed a multi-site DSEAR assessment for a steel foundry operating across 2 sites with more than 20 distinct operational areas, covering combustible wood dust, flammable liquid coatings, natural gas systems, and electrostatic discharge risk around insulating materials. The assessment delivered over 60 specific action points and zone classifications referenced against standards including BS EN 60079-10-1, BS EN 60079-10-2, and BS EN 60079-32. If your machinery manufacturing group runs several sites without a central EHS (Environmental, Health and Safety) function watching all of them, that’s the gap where basis-of-safety decisions quietly drift out of date.

Many machinery manufacturing sites store raw metal stock, coatings, solvents, and finished goods alongside the production floor, and that storage carries its own DSEAR obligations, separate from the process risk. If your site includes a warehouse or bulk storage area, DSEAR for warehousing and storage covers what applies specifically to stored flammable liquids, aerosols, powders, and combustible materials.

We wrote about the storage of combustible dust & powders in a two part series. Read Part 1 & Part 2. 

DSEAR regulations will apply to most activities that are undertaken throughout the warehousing industry (if your stored materials are capable of combustion). The HSE state that a DSEAR may apply to any of the below activities:

• storage of petrol as a fuel for cars, boats or horticultural machinery
• handling and storage of waste dust in a range of industries
• handling and storage of flammable wastes such as fuel oils
• storage and display of flammable goods i.e. paints in shops
• filling, storing and handling aerosols with flammable propellants such as LPG
• transporting flammable substances in containers around a workplace
• deliveries from road tankers i.e. as petrol and bulk powders
• chemical manufacturing, processing and warehousing
• the petrochemical industry, both onshore and offshore

If any of these activities are undertaken at your place of work, then you are legally required to undertake a DSEAR risk assessment, which must focus on the specific work activities that involve the use of dangerous substances.

We wrote about the storage of combustible dust & powders in a two part series. Read Part 1 & Part 2. 

DSEAR regulations will apply to most activities that are undertaken throughout the warehousing industry (if your stored materials are capable of combustion). The HSE state that a DSEAR may apply to any of the below activities:

• storage of petrol as a fuel for cars, boats or horticultural machinery
• handling and storage of waste dust in a range of industries
• handling and storage of flammable wastes such as fuel oils
• storage and display of flammable goods i.e. paints in shops
• filling, storing and handling aerosols with flammable propellants such as LPG
• transporting flammable substances in containers around a workplace
• deliveries from road tankers i.e. as petrol and bulk powders
• chemical manufacturing, processing and warehousing
• the petrochemical industry, both onshore and offshore

If any of these activities are undertaken at your place of work, then you are legally required to undertake a DSEAR risk assessment, which must focus on the specific work activities that involve the use of dangerous substances.

We wrote about the storage of combustible dust & powders in a two part series. Read Part 1 & Part 2. 

DSEAR regulations will apply to most activities that are undertaken throughout the warehousing industry (if your stored materials are capable of combustion). The HSE state that a DSEAR may apply to any of the below activities:

• storage of petrol as a fuel for cars, boats or horticultural machinery
• handling and storage of waste dust in a range of industries
• handling and storage of flammable wastes such as fuel oils
• storage and display of flammable goods i.e. paints in shops
• filling, storing and handling aerosols with flammable propellants such as LPG
• transporting flammable substances in containers around a workplace
• deliveries from road tankers i.e. as petrol and bulk powders
• chemical manufacturing, processing and warehousing
• the petrochemical industry, both onshore and offshore

If any of these activities are undertaken at your place of work, then you are legally required to undertake a DSEAR risk assessment, which must focus on the specific work activities that involve the use of dangerous substances.

We wrote about the storage of combustible dust & powders in a two part series. Read Part 1 & Part 2. 

The two incidents referenced on this page failed in different ways. Hayes Lemmerz never identified the aluminium dust hazard in the first place. Hoeganaes knew, from its own test data and earlier flash fires, and didn’t act on what it knew. Both ended in fatalities.

Beyond the human cost, an ignition event on a machinery manufacturing line means damaged equipment (dust-collection systems, extraction ductwork, machining centres), lost production during the rebuild, and an insurance claim that’s harder to make if you can’t show you’d assessed the risk beforehand.

If your facility:

• Generates metal dust through grinding, machining, or finishing
• Runs spray painting, powder coating, or a paint booth
• Operates heat-generating machinery or fuel-powered equipment
• Handles chemicals with flame, explosion, or oxidiser hazard symbols
• Experiences spills, leaks, or dust generation during production
• Uses gas ovens, furnaces, or charges batteries indoors
• Runs CNC (Computer Numerical Control) centres or LEV (Local Exhaust Ventilation) and dust-extraction systems on grinding and finishing lines

You likely need a DSEAR assessment. Arrange a DSEAR assessment and we’ll review your safety data sheets, run any dust or vapour testing you need, and guide you to compliance. If your team needs it, we also run DSEAR and ATEX awareness training, so the people working the floor understand the hazards as well as the paperwork does.

Learn more about DSEAR in our FREE on-demand webinar.