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Laying a pipeline. 16 steps to find out more:

1. Route study

Designing a gas pipeline involves:

  • respect for the environment;
  • minimising disruption to owners, workers and neighbours;
  • avoiding major natural obstacles;
  • keeping the route short

2. Site surveys before work starts

These enable us to prepare a report about the site before work starts; this can be used as the basis of any compensation payments at the end of the work.

3. Work access track

Once in place, this allows a constant route for machinery and storage areas for material excavated from the trench.

4. Transportation

The pipes are transported, unloaded and arranged along the access track.

5. Bending

The pipes are bent on site to match the contours of the land and changes in direction along the route.

6. Welding

The pipes are butt-welded using techniques and procedures meeting currently applicable standards and regulations.

7. Weld testing

The welded joints are x-rayed to ensure that the pipeline has been assembled correctly.

8. Coating

The welded joints are encased in corrosion-resistant sleeves.

9. The trench

Earthmoving is carried out in two stages, to separate the subsoil at the base of the trench from the topsoil.

10. Coating testing

The quality of the corrosion-resistant coating is checked just before the pipe is lowered into the trench.

11. Lowering in

The pipe is progressively laid along the bottom of the trench, taking advantage of the elastic properties of the steel in the pipes.

12. Topographic survey

A precise survey of the pipe is conducted so that a map can be drawn which accurately records the work carried out. Those maps are submitted to the local town hall.

13. Filling in

The trench is backfilled in two stages, ensuring topsoil is restored to the surface layer.

14. Hydraulic testing

The pipeline is filled with water and then tested at a pressure of approximately 100 bar to make sure it is fully gas-tight before being filled with gas. This operation is carried out under the supervision of an authority (DREAL) representative.

15. Restoration

The land is fully returned to its original state. Ditches and embankments are re-established, and field boundaries rebuilt. Soil which has been flattened by the machinery is decompacted by subsoiling.

Restoration (before)

Restoration (before)

Restoration (after)

Restoration (after)

16. Site surveys after the work

These enable us to assess damage caused and to work out the amount of compensation payable.

For more information, see:

Map of installations

Map of installations

List of Teréga territories operating in the 15 departments of the South West

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