PVC POLYOLEFINS | MATERIALS
Standing tough: latest in polyolefins
Polyolefins are still the dominant material for plastic pipes, as shown in recent applications in water transport, cable protection and geothermal heating
Polyolefins remain the most used plastic, with huge volumes consumed in the construction of plastics pipes. The toughness and relative affordability of these materials – whose properties can be raised by crosslinking or the use of different catalysts during production – make them as critical as ever in a variety of applications. Kaymac Marine & Civil Engineering recently completed a marine infrastructure upgrade in the Severn Estuary in the UK – replacing a long sea outfall pipeline that was originally constructed in 1960. The company led the £8.4 million project as the principal contractor, installing a 1.4km 560mm HDPE outfall pipe to replace the original concrete- coated steel pipe. The new HDPE pipe was manufactured by Pipelife Norge in Norway and towed 1,134
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nautical miles to the site in 11 sections. On arrival, each section underwent stringent inspections and testing before installation preparations began. This included installing more than 260 bespoke
pre-cast concrete ballast collars to stabilise the pipeline against hydrodynamic forces and buoy- ancy. These ensured the pipe remained securely in place once submerged in the trench. A key milestone was towing the first 250m section of pipe to the installation site. This seg- ment, equipped with 50 concrete collars, was positioned over the trench at low tide, sunk with guidance from the dive team, and backfilled with previously excavated spoil. The pipe installation was completed in four
separate sections, totalling 1.47km, with a diffuser head separately installed through diving opera- tions at the seaward end. A backhoe dredger
Spring 2025 | PIPE & PROFILE EXTRUSION 33
Main image: Kaymac recently
installed 1.4km of Pipelife’s HDPE pipe in the Severn Estuary in the UK
IMAGE: KAYMAC
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