Requirements and permissible pressure loads for couplings

Last updated on Tue, 11/06/2012 - 12:18

Conditions when drainage pipeworks may be exposed to an internal pressure higher than 0.5 bars:

  1. Pipes laid under the groundwater table
  2. Rainwater pipes or waste-water pipes running through several storeys without outlets
  3. Pipework operating under pressure for waste-water pumped installations

Straight runs of the pipework

Straight runs between two fixed points do not experience exceptional forces, grip collars are then not necessary.
In case of accidental overloading, the couplings will only have to address hydrostatic pressure. They generally withstand:

  • 5 bars for couplings like PAM Rapid S or PAM SMU Rapid 2 from DN 40 to 200
  • 3 bars for the same couplings for DN 250 and 300

Changes of direction and specific elements

Depending on the configuration of the pipe work, end thrust efforts can exert in changes of direction, gradient and specific components like branches and plugs for example. In these areas, the forces have to be addressed to avoid any risk of disconnection or slippage of the pipe system:

  • isolating the section subjected to thrust forces between two fixed points, like stack support pipes i.e and
  • adapting the joints (selection of couplings + installation of grip collars) between these fixed points.

To address the thrust forces, other solutions can be resorted to, like anchoring in concrete, use of thrust blocks...

Remark: under end thrust forces, where a coupling is secured with a grip collar, the maximum performance of both is limited by the weakest performance of the two products.

End thrust force under a 1m water column (kg.F).

DN 50 75 100 125 150 200 250 300 400 500 600
2 5 9 13 19 32 55 79 136 210 301
3 6 12 19 26 46 78 111 192 297 426
2 5 9 13 19 32 55 79 136 210 301

Ensure that the installation instructions for the given couplings are observed.

Specific applications

Rainwater pipes

EN 12056-3, Section 7.6.4., stipulates: Internal rainwater pipes shall be able to withstand the water column likely to occur in the event of a blockage.
The same precautions as on a pipe work liable to undergo accidental overloading should be taken: securing of bottom bends and joints with the adequate grip collars.