Hazardous area safety in the UK - DSEAR services

DSEAR requires employers to assess the risks of fires and explosions that may be caused by dangerous substances in the workplace. These risks must then be eliminated or reduced as far as is reasonably practicable. DSEAR put into effect requirements from two European Directives: the Chemical Agents Directive (98/24/EC) and the Explosive Atmospheres Directive (99/92/EC). In the UK, DSEAR is controlled and enforced by the Health and Safety Executive (HSE).

TRaC services in support of DSEAR include:

Hazardous area classification - Zoning of hazardous areas
Hazardous area risk assessment - Defining explosion risks
Hazardous area documentation - Evidence packs to support legal obligations
Hazardous area training - Training for key personnel in support of DSEAR
Hazardous area inspections - Routine inspection of electrical equipment

Compliance with DSEAR

Compliance with DSEAR encompasses many facets of business activity which is a concept that is not readily understood.

DSEAR involves:

Risk assessment of plant operations
Defining of any hazardous zones together
Installation of hazard compliant equipment
Preparation of explosion protection records

There are many other areas of the business and its activities that need to be considered. DSEAR is a piece of legislation that is concerned with the health and safety of people working in potentially explosive atmospheres. To this end, the protection of people from the effects of fire, explosions or other similar energy releasing events must be the end product that generates compliance with the regulations. In each case the measures taken must be capable of justification and will be set down in the "Explosion protection document". This document will contain written evidence of all of the compliance measures taken, together with justification for all actions and systems installed. It is the document with which the enforcing authority will judge the quality and completeness of compliance with the regulations.

For more information on the required documentation refer to HSE Approved Code of Practice (ACOP) document L138 "Dangerous Substances and Explosive Atmospheres" (paragraphs 178 to 194) and, for storage facilities, the HSE Approved Code of Practice (ACOP) document L135 "Storage of dangerous substances".

Regulation 5(2) states that a risk assessment which evaluates and ranks the manufacturing areas in which a fire explosion or other energy releasing event can occur should be available. The highest risk areas should be known so that an action plan can be produced tackling these areas first. In all cases the regulations dictate that risk is either eliminated or reduced. See sub page on Hazardous area risk assessment.

The risk assessment can be used as the basis for a further step of eliminating and reducing risk, and by doing so bring such areas into DSEAR compliance by:

The evaluation of the zones to determine if action can be taken to reduce their size and hence the risk to people working in them. This involves limiting the discharge of any material that could cause a flammable atmosphere or fire.
The collection of accurate physical data for all of the flammable substances used. This can be a difficult and time consuming task, but is essential to the compliance route and it should be stressed that the data must be accurate. It is not uncommon for material suppliers to produce data for a range of products that is the same throughout the range, even though the products are clearly different. In the case of powders, attributes such as particle size and moisture content affect this data markedly, so that a powder may have different physical properties i.e. Kst for example if the particle size and moisture content are changed.
Producing an equipment specification will be necessary for each hazardous area, which will depend on the classification of the area and the specific materials being used. This specification will be based on the collected data in 2 above. If the data is incorrect then the equipment specified may be wrong and the equipment will not be safe to use. See sub page on Hazardous area classification and equipment.
A survey of the currently installed explosion mitigation measures must be made to establish if:
1. The materials being used are exactly the same as those in the original design of the mitigation measures.
2. The materials have changed then inspection of their physical data and a recalculation of the design will establish if the mitigation measures are still valid and safe. If not, immediate action must be taken to install a new safety system.
3. Any changes have been made to plant and equipment that would invalidate the operation of the mitigation measures. This could be, for example the replacement of an explosion vent panel with a steel plate or the positioning of new equipment such that it will prevent an explosion panel opening correctly.
4. Any explosion isolation devices have been installed and if so are they are still required. Also determine if they are fully serviced and effective.
5. Any work carried out on equipment has rendered the pressure rating less than the reduced explosion (Pred) pressure. This can be caused, for example, by installing a non-pressure rated flexible coupling in a duct or vessel feed/discharge line.
6. There has been a change of any operating device that would affect the efficient operation or prevent the operation of any of the safety systems and mitigation measures.
7. Maintenance has been carried out correctly and that all systems are in good working order and that the maintenance schedules are still valid.
8. The measures installed will comply with DSEAR and prevent injury to people exposed to potentially flammable atmospheres or working in adjacent areas.
9. The current measures are still the most appropriate and effective that could be used.
Examination of the mechanical and electrical equipment to establish if it complies with the standards required for use in hazardous zones i.e. the equipment specification (see 3 above).
Surveying the areas to determine the potential for static electrical charges to occur and assess the effectiveness of the present control measures.
Installing, a routine maintenance and cleaning schedule.
Marking all pipelines and vessels with the contents if it is a hazardous substance.

Once compliance with the above has been achieved, all of the activities undertaken should be documented for inclusion in the explosion protection document.

To pursue compliance to the final stage will involve the:

Management of change and the installation of internal control systems to prevent change occurring before a full safety evaluation of all operating and safety systems have been completed. This is intended to prevent compromising any safety systems or mitigation measures that have been put into place.
Training of all operational staff in matters affecting safety relating to the handling and use of any dangerous substances.
Training of maintenance staff in the installation, inspection and maintenance of equipment for use in potentially explosive atmospheres.
Training of cleaning staff in the correct measures, techniques and equipment to be used when cleaning hazardous areas.
Development and writing of safe operating procedures.
Establishment of contingency plans to deal with emergencies cause by fire or explosion.
Development and implementation of induction and training for contractors.
The assessment of the competency of operating staff and contractors to work in areas designated as hazardous.

All of the above activities should be carried out by persons competent and trained in the requirements of DSEAR.

Useful reference material

The following HSE Approved Code of Practice (ACOP) documents are useful in completing a full DSEAR assessment:

HSE Approved Code of Practice (ACOP) document L138 "Dangerous Substances and Explosive Atmospheres".
HSE Approved Code of Practice (ACOP) document L135 "Storage of dangerous substances".
HSE Approved Code of Practice (ACOP) document L137 "Safe maintenance, repair and cleaning procedures".

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