Storage of flammable liquids in containers HSG51 Guide

HSG51 is the Health and Safety Executive's guidance on the storage of flammable liquids in containers. If your business stores petrol, diesel, heating oil, solvents, paints, or other flammable liquids, this guidance could be the difference between safe operations and a catastrophic fire or explosion.

Every year, fires involving flammable liquids cause millions of pounds in damage and put lives at risk. Many could be prevented by following HSG51's practical recommendations. Whether you run a garage, manufacturing facility, or simply store fuel for company vehicles, understanding this guidance is essential.

What is HSG51?

HSG51 "Storage of Flammable Liquids in Containers" is Health and Safety Executive guidance that provides practical advice on safely storing flammable liquids in portable containers. Published by the HSE, it covers everything from basic storage principles to detailed technical requirements for different types of facilities.

The guidance applies to flammable liquids stored in containers, drums, intermediate bulk containers (IBCs), and small tanks up to 250 litres capacity. It doesn't cover fixed installations like large fuel storage tanks or underground storage systems, which are covered by separate guidance.

HSG51 supports compliance with several legal requirements, including the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR), the Health and Safety at Work etc. Act 1974, and relevant fire safety legislation including the Regulatory Reform (Fire Safety) Order 2005.

Who Needs HSG51?

You need to understand HSG51 if your business stores any flammable liquids, including:

Motor trades — garages storing petrol, diesel, brake fluid, and other automotive chemicals
Manufacturing facilities — businesses using solvents, adhesives, cleaning agents, or industrial chemicals
Construction companies — storing fuel for plant equipment and flammable construction materials
Printing and coating operations — using inks, thinners, and coating materials
Laboratories — storing reagents, solvents, and other flammable chemicals
Maintenance facilities — using degreasers, lubricants, and cleaning solvents
Any business with generators — storing diesel or petrol for backup power

Even small quantities can be dangerous. A few litres of petrol can produce enough vapour to cause a significant explosion if ignited.

What Counts as a Flammable Liquid?

Under HSG51, flammable liquids are those with a flashpoint below 55°C. The flashpoint is the lowest temperature at which a liquid gives off enough vapour to ignite when exposed to an ignition source. Common examples include:

Petrol (flashpoint around -40°C)
Diesel (flashpoint around 55°C)
White spirit (flashpoint around 30°C)
Acetone (flashpoint -18°C)
Ethanol (flashpoint 13°C)
Turpentine (flashpoint 35°C)

If you're unsure whether a substance is flammable, check its Safety Data Sheet (SDS). This legal document must be provided by your supplier and includes hazard classifications and safe handling information. Our guide to understanding Safety Data Sheets explains how to interpret this information.

Legal Framework for Flammable Liquid Storage

HSG51 helps you comply with several overlapping legal requirements:

DSEAR 2002

The Dangerous Substances and Explosive Atmospheres Regulations 2002 require employers to assess risks from dangerous substances, including flammable liquids. You must eliminate or reduce risks so far as is reasonably practicable, provide appropriate equipment and procedures, and ensure adequate information, instruction, and training.

Health and Safety at Work Act 1974

Under Section 2 of HSWA, employers must ensure the health, safety, and welfare of employees so far as is reasonably practicable. This includes providing safe systems of work for handling and storing flammable substances.

Section 3 extends this duty to others who might be affected by your work activities, including visitors, contractors, and members of the public.

Fire Safety Legislation

The Regulatory Reform (Fire Safety) Order 2005 requires duty holders to assess fire risks and take appropriate precautions. Flammable liquid storage is often a significant fire risk that must be addressed in your fire risk assessment.

COSHH Regulations 2002

Many flammable liquids are also hazardous to health and subject to the Control of Substances Hazardous to Health Regulations. You'll need to conduct a COSHH assessment for substances that present health risks as well as fire risks.

Key Principles from HSG51

HSG51 is built around several fundamental safety principles that apply regardless of your specific circumstances:

Minimise Quantities

Store only what you need. Excess quantities increase fire risk and potential damage. Keep working stocks separate from bulk storage, and use a "first in, first out" rotation system to prevent deterioration.

Segregation and Separation

Keep flammable liquids away from ignition sources, incompatible materials, and high-risk areas. This includes separation distances from buildings, boundaries, and other hazards.

Containment

Provide secondary containment to prevent spills reaching drains, watercourses, or spreading to other areas. This might include bunds, drip trays, or dedicated storage cabinets.

Control of Ignition Sources

Identify and control potential ignition sources in storage areas. This includes hot surfaces, electrical equipment, smoking materials, and hot work activities.

Emergency Arrangements

Have appropriate fire-fighting equipment readily available and ensure staff know how to respond to spills, leaks, or fires. This links to your broader fire safety training requirements.

Storage Methods Under HSG51

HSG51 covers several storage methods, each with specific requirements:

Flammable Storage Cabinets

Purpose-built storage cabinets are suitable for smaller quantities. They should:

Be constructed of steel with appropriate fire resistance
Have self-closing doors with three-point locking
Include spillage containment (typically 25% of stored volume)
Have appropriate ventilation arrangements
Display clear hazard signs

Separated Storage

For larger quantities, dedicated storage areas may be appropriate. Requirements include:

Separation distances from buildings and boundaries
Fire-resistant construction where required
Adequate ventilation to prevent vapour accumulation
Impermeable flooring with containment
Access control to prevent unauthorised entry

External Storage

Outdoor storage can reduce risks to buildings and people but requires:

Weather protection for containers
Security measures against theft and vandalism
Appropriate separation from boundaries and buildings
Emergency access for fire services
Environmental protection measures

Practical Implementation of HSG51

Implementing HSG51 recommendations requires a systematic approach:

Risk Assessment

Start with a comprehensive risk assessment covering:

Types and quantities of flammable liquids stored
Storage locations and methods
Potential ignition sources
People who might be affected
Environmental considerations
Emergency response arrangements

This assessment should follow the principles outlined in our guide to the 5 steps to risk assessment.

Storage Planning

Plan your storage layout to:

Minimise handling and movement
Provide adequate separation distances
Allow emergency access
Facilitate inspection and maintenance
Consider future expansion needs

Container Selection

Choose appropriate containers that are:

Suitable for the specific liquid being stored
Properly labelled with contents and hazard information
In good condition without damage or corrosion
Appropriately sized for handling requirements
Compliant with relevant standards

Housekeeping and Maintenance

Maintain good standards through:

Regular inspection of containers and storage areas
Prompt cleanup of spills and leaks
Proper disposal of waste materials
Keeping storage areas tidy and well-organised
Maintaining separation from combustible materials

Training and Competence Requirements

HSG51 emphasises the importance of proper training for anyone handling or storing flammable liquids. Training should cover:

Hazard recognition — understanding the risks of flammable liquids
Safe handling procedures — proper techniques for moving and dispensing
Storage requirements — understanding why controls are necessary
Emergency procedures — what to do in case of spills, leaks, or fires
Personal protective equipment — when and how to use PPE

Regular refresher training ensures competence is maintained as circumstances change. Consider integrating this training with your broader workplace safety training programme.

Emergency Planning and Response

Effective emergency planning is crucial when storing flammable liquids. Your emergency procedures should address:

Spill Response

Immediate actions to contain and control spills
Elimination of ignition sources
Evacuation procedures if necessary
Cleanup methods and disposal arrangements
Reporting requirements to authorities

Fire Fighting

Appropriate fire extinguisher types and locations
When to fight fires and when to evacuate
Fire service access and water supply arrangements
Protection of adjacent areas and structures

Remember that different types of flammable liquids may require different fire-fighting approaches. Our guide to fire extinguisher types explains which extinguishers are appropriate for different fire classes.

Record Keeping and Documentation

Maintain appropriate records to demonstrate compliance and support ongoing management:

Risk assessments — including reviews and updates
Training records — who was trained, when, and on what
Inspection records — regular checks of storage areas and equipment
Incident records — any spills, leaks, or near misses
Maintenance records — for storage equipment and fire protection systems

These records support your legal compliance and help identify trends or areas for improvement. They're also valuable if enforcement authorities visit your premises.

Common Mistakes and How to Avoid Them

Based on HSG51 and enforcement experience, common problems include:

Inadequate Risk Assessment

Many businesses underestimate the risks or fail to consider all scenarios. Ensure your assessment is comprehensive and considers cumulative effects of multiple substances.

Poor Housekeeping

Allowing combustible materials to accumulate near flammable liquid storage significantly increases fire risk. Maintain clear separation and good housekeeping standards.

Inadequate Training

Staff who don't understand the risks are more likely to cause incidents through unsafe practices. Invest in proper training and regular refreshers.

Ignoring Small Quantities

Even small amounts of highly flammable liquids can cause serious incidents. Don't ignore storage requirements just because quantities seem minimal.

Mixing Incompatible Substances

Some flammable liquids shouldn't be stored together due to chemical incompatibility. Check Safety Data Sheets for specific storage requirements.

Enforcement and Consequences

Failure to properly store flammable liquids can result in serious consequences:

HSE Enforcement

HSE inspectors can issue improvement notices requiring specific actions within set timeframes, or prohibition notices stopping work immediately if there's serious risk. Prosecution is possible for serious breaches, with unlimited fines in the Crown Court.

Fire Authority Action

Fire and Rescue Services can issue enforcement notices under fire safety legislation, requiring improvements to fire precautions or restricting storage quantities.

Environmental Enforcement

The Environment Agency may take action if flammable liquid storage poses environmental risks, particularly regarding spill containment and groundwater protection.

Insurance Implications

Insurers may refuse claims or increase premiums if storage doesn't meet recognised standards. Some policies specifically require compliance with HSG51.

Integration with Other Safety Requirements

HSG51 doesn't exist in isolation. Consider how flammable liquid storage integrates with:

Fire safety management — including your fire safety policy and emergency procedures
COSHH compliance — for substances that are both flammable and hazardous to health
Environmental management — preventing contamination and managing waste
Security arrangements — preventing theft and unauthorised access
Workplace transport safety — if moving containers around your site

Staying Current with HSG51

HSG51 is periodically updated to reflect new knowledge, technology, and regulatory changes. Stay current by:

Checking the HSE website for updated versions
Reviewing your procedures when circumstances change
Learning from incidents in your sector
Engaging with trade associations and professional bodies
Regular training and competence updates

What to Do Now

If you store flammable liquids, take these steps:

Get a copy of HSG51 — download it free from the HSE website
Review your current storage arrangements — against HSG51 recommendations
Conduct or update your risk assessment — following the 5-step process
Check staff training needs — ensure everyone handling flammable liquids is competent
Review emergency procedures — including spill response and fire-fighting arrangements
Consider professional advice — for complex situations or major storage operations

The cost of implementing HSG51 recommendations is minimal compared to the potential consequences of a fire or explosion. Don't wait for an incident to take action — every day of non-compliance increases your risks.

Need Help with Flammable Liquid Storage?

HSG51 provides comprehensive guidance, but every situation is different. If you're unsure how to apply the guidance to your specific circumstances, or need help conducting risk assessments and implementing controls, get in touch. We can help you understand your obligations and develop practical solutions that keep your people and premises safe.