Operating principle of grooved couplings

Grooved coupling parts

Grooved coupling consists of three components:

  • The two-piece coupling housing which encloses the gasket and holds it in place at the pressure and vacuum. The coupling halves are designed to fit tightly in the groove around the entire circumference of the pipe which provides a mechanical interlock which prevents axial movement of the pipes.
  • Rubber gasket
  • Bolts with oval neck which fits into the couplings’ matching oval holes and flange nuts which provide a secure locking screw connection.

Operation of the gasket

The rubber gasket has a special design with “C” profile that creates an effective seal in three steps:

  • When assembling stretched rubber gasket that is slightly smaller than a pipe diameter of the two pipe ends and create a first seal.
  • The coupling halves are then placed around the gasket which adapts to them. The coupling halves are bolted together to further improve the sealing.
  • When the piping system is pressurized, a ”pressure reserve” is created due to the profile of the gasket. The sealing lips are pressed at the increasing pressure harder down against the gasket seating surface which creates the third seal and makes the connection completely leak-proof and airtight.

Working temperature of the gaskets is -34°C to +110°C.

Difference between flexible and rigid grooved couplings

NordicFlow® Grooved coupling are available in two variants: rigid and flexible

The rigid couplings provide a completely rigid connection similar to traditional flanged, welded and threaded piping connections with the help of grip teeth. It eliminates or reduces angular deflection, axial displacement and rotation after installation. This makes it easy to install even very long pipelines without angular deflection.

The flexible couplings allow some angular misalignment and axial movement, which means that they can be used to create smooth bends and absorb thermal expansion ja contraction in the piping system. In some cases, traditional expansion joints, loops, and other expansion devices may even be completely excluded in the system with the use of flexible couplings.