Sealing a localised area of the pipe reduces the sealing area hence the loads which need to be restrained. Due to this, these clamps are much lighter and easier to handle than a traditional repair clamp which encapsulates the whole circumference of the pipe.
The localised sealing area is provided by a circular ‘D’ seal, mounted in a profiled groove which confirms to the pipe outside diameter. The size of the repair which can be accommodated with this design can vary but must be small in relation to the pipe diameter, less than 25%.
The clamp is installed by assembling the strap around the pipe and connecting the two elements together. Once connected, the strap can be orientated to provide easy access for assembling the seal housing.
The clamp can then be relocated to the correct position and the strap bolt tightened. The elastomeric seal on the pipe can accommodate a poor surface finish on the pipe outside diameter, however, coatings must be fully removed and any deep gouges must not impinge on the seal contact area.
The strap bolts do not require a high torque as they are only required to provide the initial seal. Once pressure is applied to the seal housing, the pipe seal will become energised by the differential area acting across the cartridge. This is an important feature on a thin pipe wall, where the pipe would deflect with preload on the strap bolts.
