Technical solutions


Trenchless pipe laying techniques

With the growth of urbanisation, demography and the scarcity of drinking water, project managers have to preserve our natural resources by ensuring that water is transported with the highest possible regard for sanitary conditions and environmental criteria. Trenchless pipe laying is a modern piping technique that addresses these concerns.

Thanks to the exceptional mechanical qualities, anchored joints and special coatings, PAM ductile iron products and systems are ideal for trenchless pipe laying. As an alternative to the traditional method of laying in trenches, these techniques of micro tunneling, pipe bursting or pulling through a casing are ideal for locations where conventional methods of implementation would be difficult, if not impossible.

For example, crossing through dense urban areas, rivers, canals, factories, railway lines, roads, and unstable terrain. When pipes are being laid, the nuisance caused to citizens through the slowing down of road and pedestrian traffic, diversion of traffic, noise and disturbance of local commercial activity has to be limited as much as possible.
Trenchless pipe laying techniques keep the social costs of a project to a minimum.


Pipe laying by micro tunneling

The curved trajectory of micro tunneling makes it possible to pass a pipe under obstacles starting from ground level. This technique involves three distinct steps:

  1. Creation of a pilot hole using a drilling machine guided from the exterior;
  2. Boring of the pilot hole; and
  3. Pipe assembly and pulling of the string of anchored pipes from the downstream well towards the upstream, using the drilling machine.



More than 90,000 linear meters (the equivalent of two Channel Tunnels) of PAM pipes have been laid to date using micro tunneling.

trenchless pipelaying
Frist step of the drilling, assisted by a drilling unit and bentonite
exit of the earthworks
Second step of the drilling: exit of the earthworks


Pipe laying by pipe bursting

Pipe bursting is used to replace one damaged pipeline with another of the same diameter or, often, a slightly larger diameter. The old pipeline can be burst in-situ or removed piece by piece and broken up as it is pushed out of the tunnel. This replacement procedure can only be used for straight sections. An initial diagnosis is required, with a video inspection of the pipeline to be replaced, to ensure that there are no obstacles to impair its extraction or destruction.

pipe bursting
Pipe bursting

Pipe laying by pulling through a casing

Pipe laying through a casing consists of introducing a pipeline intended to transport a fluid (drinking water, waste water, rain water, dry networks, etc.) into a circular sleeve that already exists or is installed specifically for this application. Ductile iron pipelines are perfectly suited for this application since the anchored joints can withstand significant pulling forces while retaining the flexibility offered by elastomer gaskets. This pipe laying method is suitable for specific rehabilitation techniques, for laying new networks that cross a natural obstacle, and for trenchless work.

pipelaying in casings
Pipelaying through casings

Special coatings

The coatings in the DIREXIONAL range are made of extruded polyethylene, reinforced polyurethane or cement mortar, and fully address the requirements of trenchless technology. They completely protect the pipes from any impact that might occur during pulling and also improve the way they slide through the ground.

Saint-Gobain PAM microtunelling
Pipeline Direxional - Microtunelling under the Loire

Calculation tools

Calculation apps for trenchless pipe laying, ductile iron

Saint-Gobain PAM provides two calculation tools to improve project organisation on construction sites:

Associated products
Associated documents
Pictures and videos
  • Saint-Gobain PAM microtunelling
  • Saint-Gobain PAM microtunelling
  • Direxional - Saint-Gobain PAM microtunelling
  • Saint-Gobain PAM microtunelling
  • Saint-Gobain PAM microtunelling
  • Direxional - Saint-Gobain PAM microtunelling
Logo de la gamme Direxional

See also

Ductile iron pipes for energy, snow, geotechnical, trenchless, pre-insulation, and foundation solutions
Ductile iron pipes DN 60 to 1000 can be laid without a trench using either techniques: new pipe laying by horizontal directional drilling (HDD), or trenchless replacement of existing pipes.