Viewpoint: five steps to defusing explosive situations

Owners and operators whose companies are responsible for processes involving flammable or explosive materials must be able to demonstrate compliance with the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR).

Meeting these regulatory requirements requires an organisation to consider the risks and appropriate mitigation measures through the design, construction, operation and maintenance of their facilities.

Five areas of focus are key to this:

Hazard and risk assessment

DSEAR risk assessments should:

• Be current (typically less than five years old)
• Cover all flammable or explosive liquids, gases and powders
• Provide a breakdown of the hazards
• Provide an assessment of the risks that they present
• Explain what mitigation of ignition sources is in place

Companies also need to define and document the areas where flammable and/ or explosive atmospheres exist. This must describe the extent and types of zones and include the potential sources of release.

As gases in flammable atmospheres can rise or fall, the documentation should include side elevations, as well as plan views. In addition, separate assessments should be made of the risks from external sources of ignition, including lightning and radio frequency radiation.

Engineering and design

Electrical installations must document the use of a standard for the design, selection and installation of equipment used in hazardous atmospheres. They must also consider the relevant wiring regulations.

Lightning protection systems need to list which of four lightning protection levels (LPL) apply to an installation, demonstrating that the protection design adopted meets the requirements of the appropriate level lightning protection system (LPS).

Detection systems for fire, flammable or toxic gases and oxygen require appropriate selection and design to ensure they are fit for purpose and provide the desired mitigation

Static control measures must address any earthing and bonding requirements. Sacrificial anodes or a DC current source, used to provide corrosion protection for underground or buried pipework, are a potential ignition source which must be considered if they are used in hazardous areas.

Detection systems for fire, flammable or toxic gases and oxygen require appropriate selection and design to ensure they are fit for purpose and provide the desired mitigation. Considerations relate to types of sensor used, the position of detectors and where alarms or indicators are located.

Operation and maintenance

All the systems discussed in the section above require appropriate and clearly documented operation and maintenance procedures. Electrical installations must also adhere to the appropriate British standard, typically parts 17 and 19 of BS EN 60079.

Each of these systems demand clear maintenance procedures and policies scheduled by the organisation’s maintenance system.

Equipment installed or used in hazardous areas requires an inspection process appropriate for the protection concept used. This will cover the grade of inspection (visual, close or detailed) and the frequency of these inspections. Inspection and testing must extend to electrical circuits and installations and earth connections.

Competence

The organisation must demonstrate that it is taking appropriate steps to ensure that all personnel, both in-house and contractors, have the appropriate knowledge, skillsets and competence to conduct their work.

All staff involved in the installation and maintenance of equipment used in hazardous areas should be trained to appropriate Competency in Explosive Atmospheres (CompEX) standards

All staff involved in the installation and maintenance of equipment used in hazardous areas should be trained to appropriate Competency in Explosive Atmospheres (CompEX) standards.

As these cover a wide field, organisations must ensure that staff training has included all units relevant to their work. The competency management programme should include an on-going training regime that ensures staff skills are routinely refreshed.

Safety management

Finally, as part of a robust safety management plan, an organisation must understand how the systems and processes described above contribute to overall safety, and how the site-wide safety plan addresses the needs of explosive atmospheres.

• Jeremy Gadd is managing director of GSE Systems