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Hazardous substance pipe system

Context and challenges

The total length of the French hazardous substance piping system is 50,000 km, breaking down as follows:

  • 73% for natural gas,
  • 19% for petroleum products (raw petroleum and refined products),
  • 8% for chemicals (ethylene, oxygen, nitrogen, hydrogen etc.)

Most of these pipes are underground, with the exception of the elements required to operate them (pumps, compressors, gas pressure regulators, switching stations, isolating valves). 2Safety challenges2 The main cause of a loss of containment in a supply pipe is external hazard, generally during works carried out near the structure. Over half of the leaks, and nearly all complete ruptures (for example the Ghislenghien accident in Belgium on 30 July 2004) are due to this. Other causes include internal or external corrosion, material or weld defects, joint or flange leaks, chemical reactions etc.

In case of accident, the products released from the pipe can develop, depending on their characteristics, a flammable, explosive or toxic cloud. Liquid products can also contaminate the environment. The prevention of external hazards requires that information be provided to the owners or managers of land crossed by a pipeline and strict compliance with the regulations relative to works declarations (DICT).

To prevent other causes of leakage, operators implement constructive measures for new installations and monitoring resources for installations in operation. To avoid external corrosion, steel tubes are coated with leakproof protection (previously pitch, now polyethylene or polypropylene) and protected by a cathodic protection system. Operating pipes are monitored by periodic re-tests or by the passage through the pipe of different types of scrapers with instrumentation to detect minor leaks (acoustic measurements) or different categories of defects such as distortions, loss of thickness, cracks (magnetic or ultrasound measurements). The tubes affected are then easy to locate and repair or replace, or are subject to reinforced surveillance.

Due to their potential risks, hazardous substance piping systems undergo a safety audit analysis outlining the potential risks inherent in the structures and those incurred by these structures due to their environment. They are therefore affected by the public notification procedure to allow the municipalities or group of municipalities to exercise their prerogatives in terms of urban planning, by focusing on preventing these risks and protecting the people who may be exposed to them. Public notification is based on the definition of the hazardous areas set by the ministerial order of 29 September 2005 relative to the evaluation and consideration of the occurrence probability, kinetics, effect intensity and seriousness of the consequences of potential accidents in the risk assessment reports of permit holding installations.


Legislation specific to transported fluids:
Natural gas: Amended decree no. 85-1108 of 15 October 1985 and amended decree no. 70-492 of 11 June 1970;
Hydrocarbons: Amended decree no. 59-998 of 14 August 1959, amended decree no. 59-645 of 16 May 1959 and amended decree no. 89-788 of 24 October 1989;

Chemicals: Amended decree no. 65-881 of 18 October 1965;

Harmonised multi-fluid legislation:
Amended decree no. 91-1147 of 14 October 1991 relative to the execution of construction works in the vicinity of certain underground, overhead or underwater transport or distribution structures;

Order of 4 August 2006 regulating the safety of combustible gas, liquid or liquefied hydrocarbon and chemical transport piping system;

Circular of 4 August 2006 relative to the public notification to be provided within the framework of the establishment of urban planning documents in terms of hazardous substance piping systems.

Useful sites

Ministry of economy and finance, vice-directorate for industrial safety and metrology