High Pressure Pipe Couplings

Pipe clamps and hubs are a safe, easy and economical way of joining high pressure pipes compared with traditional flanges.

A pair of clamps with a tapered recess machined into them fit over tapered hubs which are welded onto the ends of the pipe. A firm, but elastic seal ring fits into grooves machined in the faces of the hub and provide an alignment spigot for assembly and an effective seal. The clamps are pullet together with either two or four bolts.

The 15 degree taper of the hubs is sufficiently large to make initial fitting and tightening easy.

50 to 100NB clamps are held together by 2-bolts and nuts while 150 to 300NB clamps are pulled up with 4 studs with self-aligning nuts. These clamps are all ANSI class 1500 (MPa) rated. All the fasteners are low tensile (grade 4.6), galvanized and have generous corrosion allowances.

An earlier range of two bolt clamps is also available for low pressure applications (ANSI class 900 and below – 16MPa).

The hubs are made of wrought steel with guaranteed properties and are factory welded onto the pipes. The weld is as simple as a normal butt weld done by code welders to a controlled standard.

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  • Designed in accordance with ANSI/ASME VIII.
  • Designs tested and approved by CSIR Miningtek to burst pressure in excess of 5 times the rated working pressure.
  • Installation is quick and easy.
  • The seals are robust and re-usable many times over.
  • No secondary leak protection baffles are needed due to the contorted leak path of a possible leak. The eliminates the risk of a person being jetted by a poorly assemble joint.
  • The seal is mechanically and pressure loaded ensuring that the seal will work under positive, negative and alternating pressures.
  • The clamp hub and joint is less expensive than flanges of similar rating.
  • The clamp and hub joint is much quicker to install than flanges of similar rating due the smaller number of bolts.
  • The joint can be twisted to any angle eliminating the bolt-hole alignment requirements of flanges.
  • The hub is full bore and therefore no flow restriction or turbulence is induced.
  • The relief space provided between the clamps allows corroded bolts to be removed with a cutting torch without damaging the clamp.


Technical Specifications

  • Seal: Robust UHMPE unit (can be reused time and time again)
  • Hubs: ST52
  • Clamp: Cast steel (machined to ensure a correct wedge contact surface)
  • Bolts/Studs: Gr 4.6 galvanised