Pipelines fire & emergency services

The Pipeline Safety Regulations, 1996 gives local authorities the task of producing emergency plans. These are then used in case of accident hazard pipelines (MAHP) within the area. Health and Safety Executives will then notify the council of the pipelines that require planning in the area.

The following gives an overview of what happens when the emergency services respond to a pipeline incident, showing how the existing procedures of various organisations would be applied and co-ordinated. It follows the recommended national format for Pipeline Safety Plans.

Pipeline system

The operator for the notified Major Accident Hazard Pipelines in this area is Transco (formerly British Gas) and supplies natural gas.

Transco supply maps showing pipeline routes and data to the Emergency Planning Team. This information is shared with the Fire Service but for security reasons this information is not available to the public.

Detecting a hazard

An incident involving a high-pressure gas pipeline can be identified as follows:

• Release of gas - resulting in a pipeline puncture or rupture, leading to a pressurised release of natural gas. All pipelines operating under 75 bar (which is used for the National Transmission System) contain odorised gas
• Duration of pipeline leaks - when a high-pressure pipeline fails, immediate and rapid de-pressurisation occurs over a matter of seconds, and is followed by relatively stable flow as the pipeline unpacks due to the leak and continued pumping of gas into the pipeline
• Blast effects and projectiles - the pressure blast at the time of failure can be significant in close proximity to the pipeline, cover material over the pipeline may be thrown into the air at high velocity, but the serious effects will diminish with distance
• Fire and explosion - The ignition of any release of gas will cause a flare, which may have serious effects due to thermal radiation. People can be shielded indoors but radiation levels may be sufficient for the buildings to catch fire.

If a release of gas does not ignite immediately, it will form a cloud, which will disperse over large distances. If a cloud of gas ignites it may burn back as a flash fire to the point of origin.

As it disperses it will be diluted with air, the concentration falling below the lower explosive level (LEL) when it will no longer present a fire hazard. The distance over which such a release may disperse depends on the type of release and the prevailing weather conditions. Concentrations and duration may be estimated using plume modelling.

It is important that ignited gas is not extinguished unless specifically requested by the Transco on site controller.

Noise

The release of high-pressure gas creates a great deal of noise, which can be very intense leading to temporary hearing damage. High noise levels can also be disorientating and may cause unexpected behaviour in people.

Plan activation

In view of the extreme nature of a high-pressure pipeline failure it is likely that initial notification will be by a member of the public either by calling 999 or to the gas emergency number.

There is a single national gas emergency number for all notifications: 0800 111 999

For further information contact

E-mail: emergency.planning@towerhamlets.gov.uk
Tel: 020 7364-4181 (office hours only)
Fax: 020 7364-4181 (office hours only)
Out of office hours: Contact LBTH call-centre: Tel: 020 7364-7000
website: http://www.hse.gov.uk.

Pid No: 794