HSG71 is HSE guidance for the storage of packaged dangerous substances in warehouses, compounds and similar facilities. It covers risk assessment, segregation, racking, ventilation, spill containment, fire and explosion risks, emergency planning and employee training. The guidance applies regardless of facility size and should be used alongside current legislation such as DSEAR, COSHH and COMAH where relevant.
HSG71, Chemical warehousing: The storage of packaged dangerous substances, is guidance published by the Health and Safety Executive for organisations responsible for storing packaged dangerous substances.
The HSE currently lists the fourth edition, published in 2009.
The guidance is aimed at anyone responsible for dangerous-substance storage, regardless of the size of the facility.
It applies particularly to:
Its purpose is to provide good-practice measures for eliminating or reducing risks to people arising from the storage of packaged dangerous substances.
No. HSG71 is HSE guidance rather than a separate piece of legislation.
The legal duties affecting a chemical warehouse may arise from several sources, including:
HSG71 provides practical guidance on how many of the storage risks associated with packaged dangerous substances can be controlled.
HSE continues to list HSG71 as guidance for chemical warehousing, with the current published edition being the fourth edition from 2009.
Because the publication predates some later legislation and regulatory changes, individual legal references within HSG71 should be checked against current requirements.
For example, HSG71 refers to the former COMAH 1999 Regulations, which have since been replaced in Great Britain by the Control of Major Accident Hazards Regulations 2015.
The underlying warehouse risk-control principles remain useful, but current legislation and current regulatory guidance should always take precedence where requirements have changed.
HSG71 is concerned with packaged substances that can create significant health, fire, explosion or other safety risks when stored.
These can include materials stored in:
The hazards can include flammability, toxicity, corrosivity, oxidising properties, dangerous reactions and other risks associated with individual substances.
HSG71 explains that risk assessment is fundamental to deciding how dangerous substances should be stored.
Relevant factors include:
Risk assessments should be reviewed whenever significant changes occur, including changes to substances, quantities, equipment or warehouse operations.
HSG71 describes segregation as one of the most important risk-control measures in the storage of dangerous substances.
Segregation can help prevent:
Dangerous substances may need to be stored in dedicated warehouses, separate compartments or clearly segregated areas depending on the hazards involved.
No. HSG71 provides general segregation recommendations based on dangerous-goods classifications, but it specifically warns that these do not account for every chemical incompatibility.
Substances that appear compatible in a general table may still react dangerously when mixed.
Safety Data Sheets and other reliable chemical compatibility information should therefore also be consulted.
Examples of potentially dangerous combinations include:
Racking used for dangerous substances should be properly designed, constructed, loaded, inspected and maintained.
HSG71 advises that:
For example, storing incompatible substances directly above and below each other may increase the consequences of a leaking container.
Where warehouses do not use racking, packaged chemicals may be stored in block stacks.
HSG71 advises that maximum stack size and height should be controlled so that:
Information from the container manufacturer or supplier should be considered when establishing safe stacking limits.
Drums and Intermediate Bulk Containers should be stored in a way that protects them from physical damage, corrosion, unstable stacking and incompatible materials.
Important considerations include:
Particular care may be necessary when storing flammable liquids in plastic or composite IBCs because their behaviour in a fire can differ significantly from metal containers.
HSG71 recommends suitable arrangements to prevent spilled chemicals escaping from outdoor storage areas.
For many packaged chemical storage arrangements, an impervious sill or low bund may be used.
The guidance describes a containment volume of at least 110% of the capacity of the largest individual container within the bund.
The storage surface should also be impervious and arranged so that spilled liquid can be directed to a safe contained location.
Alternative arrangements may include drainage to a suitable remote sump, interceptor or other controlled containment system.
The correct containment capacity and arrangement should still be determined from the substances, quantities, packaging, environmental requirements and site-specific risk assessment.
Floors within chemical storage buildings should be compatible with the materials being stored and designed to prevent uncontrolled spread of liquids.
Depending on the warehouse design, containment can be achieved using:
HSG71 advises that liquid spillages should not be allowed to flow into areas where incompatible substances are stored.
Where individual bunded areas are used, HSG71 gives a bunded volume of 110% of the largest receptacle within the bund.
Where a leak of flammable liquid or gas could produce dangerous concentrations of vapour, adequate ventilation is required to prevent accumulation.
Natural ventilation can include permanent openings at high and low levels in external walls.
Where openings are provided on opposing walls, they can encourage cross-flow, while high- and low-level openings can promote air circulation through thermal movement.
The DSEAR assessment should also consider ventilation when vehicle doors and loading bays are closed outside normal operating hours.
Large buildings or storage arrangements that cannot achieve suitable natural air movement may require mechanical ventilation.
Where mechanical ventilation is relied upon as a safety measure, HSG71 advises that it should operate as required and that failure can be monitored using suitable airflow-detection equipment linked to an alarm.
Where there is uncertainty about the effectiveness of the ventilation system, a competent ventilation engineer may need to measure the actual air-change rate achieved.
Gas cylinders should be protected against falling, physical damage and inappropriate storage conditions.
HSG71 advises that cylinders should be stored securely so that they cannot topple.
Storage arrangements should also consider:
More specific gas-cylinder guidance may be required depending on the gases and quantities involved.
Aerosols can create particular warehouse fire risks because containers exposed to heat may rupture and become projectiles, spreading fire to other areas.
HSG71 advises that aerosols should not be stored close to:
Where practicable, aerosol stock should be stored separately or segregated using suitable fire-resistant construction.
The quantity stored within an individual compartment may also need to be limited to reduce potential fire severity.
Forklifts and other vehicles can create significant risks in chemical warehouses through impact damage, ignition sources and accidental release of packaged chemicals.
The warehouse risk assessment should consider:
Damage caused by vehicles should be treated seriously because even minor impact can compromise containers, racking or containment systems.
Yes. Where flammable gases, vapours or other explosive atmospheres may occur, hazardous-area classification should be considered as part of the DSEAR assessment.
The assessment should determine:
Equipment used in classified areas should be appropriate for the zone and substances involved.
See our DSEAR Regulations guide for further information.
The appropriate fire-protection measures depend on the substances, quantities, packaging and potential accident scenarios at the site.
Depending on the risks, controls may include:
Fire protection should be designed around the hazards of the stored materials rather than applying one generic warehouse specification.
A current inventory is important for managing a chemical warehouse and for providing information during an emergency.
HSG71 recommends maintaining records showing the quantity and location of dangerous substances within the store.
The inventory should be updated to reflect stock movements and should be accessible from a location unlikely to be affected by an incident.
This allows emergency responders and site personnel to understand what substances may be involved and where they are located.
Employers should establish emergency arrangements for foreseeable incidents involving dangerous substances.
The primary objective is to ensure that people can evacuate to a place of safety.
Depending on the facility, emergency arrangements may include:
Emergency arrangements should be tested periodically and reviewed when circumstances change, including when the quantities or types of dangerous substances stored are significantly altered.
Employees should receive information, instruction and training appropriate to the hazards and activities involved in their work.
This can include:
Training should be reviewed when substances, processes or storage arrangements change.
HSG71 is broad guidance for the storage of packaged dangerous substances, while HSG51 focuses specifically on flammable liquids stored in containers.
A chemical warehouse holding significant quantities of flammable liquids may therefore need to consider both documents.
See our HSG51 flammable-liquid storage guide for further information.
Large chemical warehouses may fall within COMAH where dangerous substances are present at or above the relevant qualifying quantities.
HSG71 provides useful warehouse risk-control guidance, but COMAH establishments can require additional measures reflecting their major-accident hazards.
The current Great Britain regime is the Control of Major Accident Hazards Regulations 2015.
See our COMAH Regulations 2015 guide for further information.
Chemstore designs and manufactures hazardous material storage facilities that can be configured around the substances, quantities and controls identified through a site’s risk assessment.
For larger and more complex requirements, Chemstore provides bespoke chemical warehouses with options including chemical segregation, bunded containment, fire-rated construction, ventilation, fire suppression, temperature control, monitoring, quarantine areas and restricted access.
For drums and IBCs requiring dedicated bunded storage, the Hazvault range provides a range of packaged chemical storage configurations.
Storage facilities should be specified according to the dangerous substances, quantities, incompatibilities, fire and explosion risks, operational requirements and findings of the site-specific assessment.
A Chemstore product or warehouse does not by itself make a site compliant with HSG71, DSEAR, COSHH or COMAH.
The Health and Safety Executive provides HSG71 directly on its website.
This page summarises HSG71 and provides general information only. It does not replace the HSE publication, current legislation, Safety Data Sheets, environmental requirements, a site-specific risk assessment or advice from a competent person.
Because HSG71 was published in 2009, references within the original publication to legislation and external guidance should be checked against current requirements before being relied upon.
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