Engagement développement durable - Saint Gobain PAM

Search product

Bridge crossing pipe laying

Technical solutions

Bridge crossing pipe laying


Bridge crossing with a push-in joint main involves determining:
– the support system,
– the accommodation of both bridge and main thermal expansions,
– the anchoring of components subjected to hydraulic thrust,
– the protection against freezing, if necessary.

There are two principal installation systems, the choice depending on the type of structure:

  • pipeline secured to the structure,
  • pipeline independent of the structure.

Systems shown below correspond with the usual types of bridge crossings ; they are merely given as examples and do not represent the variety of situations that may be encountered.
Every bridge is a special case and must be specifically studied. The initial concern is to ensure that the structure can support the weight of the main and that provision of anchorages is possible.

Pipelines fixed solidly to the structure

Supports

– one per pipe,
– every support behind a socket,
– supporting saddles (α = 120° is a good precaution),
– securing collars,
– rubber protection.

Thermal expansion

Relative expansion: every clamp must be adequately secured and act as a fixture to the bridge. Between each of these supports, which are solid with the pipe and bridge, the push-in joints act as expansion compensators, absorbing the expansion of a length of pipe.
Overall expansion (ΔL): depending on its amplitude, the overall expansion at the bridge ends is accommodated by either a simple socket joint (in the case of a traditional short span masonry bridge), or by an adequate size expansion accommodator (in the case of an open end bridge).

Anchorage

Every component subjected to hydraulic thrust (bends, tees, valves...) must be held by an anchoring system.
The supports must be of sufficient dimensions to secure the correct alignment of the pipes and to withstand the hydraulic thrust. Provision of an adequate safety margin on the support dimensions is recommended, to compensate for hydraulic forces due to any misalignment of the pipes.

Pipeline independent of the structure

Supports

Each support is solid with the pipeline and independent of the bridge movements. Several techniques may be used, using sliding or rolling on rails or rollers, depending on the magnitude of the expansions.
The support sliding forces must be compatible with the anchoring system :
– one support per pipe,
– every support behind a socket,
– a saddle support,
– a securing collar,
– a rubber protection.

Thermal expansion

The pipeline expands and contracts independently of the bridge. The joints are anchored: they facilitate assembly and play a part in distributing the overall pipeline
expansion. This expansion, ΔL, is taken up by an adequately sized expansion absorber at the free end of the main.

Anchorage

Every component subjected to hydraulic thrust (bends, tees, valves...) must be stabilized by an anchoring system.
Sliding supports must be of adequate size to maintain the pipeline correctly aligned and to withstand the effects of hydraulic thrust.
Provision of an adequate safety margin on the support dimensions is recommended, to compensate for hydraulic forces due to any misalignment of the pipes.

Images

Bridge crossing pipe laying - water - ductile iron pipe - Saint-Gobain PAM
Bridge crossing pipe laying
Bridge crossing pipe laying - water - ductile iron pipe - Saint-Gobain PAM - INTEGRAL
INTEGRAL range - Bridge crossing pipe laying
ISOPAM - pipeline - pre-insulated
ISOPAM pipeline bridge crossing

See also

Ductile cast iron pipelines are suitable for all soil types. Saint-Gobain PAM offers a comprehensive network that can adapt to any environmental or soil conditions.