Strata Precision Plastics have been involved with Iplex Pipelines in the development & manufacturing of Restrain™ since 2004 when we purchased the technology from Europe to acheive a joint that provides a fully sealed joint suitable for trenchless technology, with particular emphasis on HDD & Microtunnelling.

RESTRAIN PVC pipe is currently available in DN 100, 150, 225 and 300 sizes and has been developed specifically for installation by trenchless methods. It comprises a threaded socket and spigot joint with an integral rubber seal ring. The joint and seal ring system are fully compliant with AS/NZS1260 PVC pipes and fittings drain waste and vent applications. The joint is designed to accommodate either tensile or compressive loads, thereby providing versatility and use of various trenchless installation methods including:

  * HDD
  * Auger boring
  * Slip Lining
  * Guided boring
  * Pipe bursting/cracking
  * Pipe reaming

Iplex Pipelines in New Zealand initiated development of the RESTRAIN pipe system. Hydrostatic testing of the elastomeric seal ring was conducted at Iplex’s independently accredited laboratory, with tensile and compression testing at the Massey University Institute of Technology and Engineering.

For connection of laterals to a mainline installed using RESTRAIN, we have available a Ultra Rapid Clamp which provides a quick and efficient means of connection.


Elastomeric seal ring compliance with AS / NZS 1260

The RESTRAIN seal ring complies with Section 3.4 ‘Tests on Elastomeric Seal Rings’ of AS/NZS 1260. The hydrostatic and liquid infiltration tests examine resistance to internal and external pressure. The contact width and pressure test confirms a minimum interface pressure and minimum continuous contact width between the elastomeric seal and the spigot of the pipe. This is to effectively eliminate tree root intrusion and liquid infiltration/exfiltration at joints in correctly installed u-PVC pipelines.

Tensile and compressive performance

Tensile and compression testing of RESTRAIN joint assemblies established the ultimate performance of the joint. Appropriate factors of safety were determined, giving maximum tensile and compressive loads for installation.

Laboratory testing on PVC-U material samples established a baseline for the pipe material in use.

Initial field-testing by guided auger boring, followed by conventional horizontal directional drilling (HDD) technology, tested the functionality of the RESTRAIN system during construction. The first successful HDD installation of DN 150 RESTRAIN was 105 m between manholes at an invert of 4 m.

Unlike polyethylene pipe, no site welding is necessary for the sewer main or connection of the laterals. As a result there would not be long pipe strings to block driveways and disrupt the movements of traffic and residents in the area. Should a project be undertaken in mid winter, on a ‘live’ sewer line, in wet conditions, and with temperatures as low as –10oC, the difficulties of site welding polyethylene pipe would be completely eliminated.

A further advantage of the RESTRAIN system was that pipe could be undone and removed from the excavation if drilling difficulties occurred. The pipe could then be re-used once the operation was back to normal.

For more information on Restrain™ click here




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