From the magazine

New PE pipe systems

Whilst attractive from an economic and environmental viewpoint, trenchless installation can be demanding on polyethylene (PE) pipe as gouges and scores to the outside surface of the pipe can develop into cracks. In response, polymer suppliers have developed high stress crack resistant (HSCR) PE100 materials that have the ability to cope with surface damage by dramatically reducing the rate at which any cracks can propagate through the pipe wall. This gives engineers the necessary confidence to specify PE pipes in the most difficult circumstances, as illustrated in the following case studies.

Attaining a higher resistance to cracks

Most HSCR PE100 materials, including BorSafe䋢HE3490-LS-H from Borouge, use hexene as the co-monomer rather than the butane, which is used in most PE100 materials. Under the correct polymerisation conditions, this leads to a PE molecular structure that has longer side branches. This results in tie molecules that have a much greater resistance to the propagation of the crack through the pipe wall, which slows down both the initiation and growth of the crack. In international standards
(ISO 4427 and ISO 4437) PE100 pipes are required to have a minimum time of 500 hours before failure in the notched pipe test, but HSCR PE100 materials should achieve failure times in excess of
8,760 hours (one year).

Renovating the watermains in Shanghai, China

The population of the city of Shanghai in China is growing at 5 per cent per year and has now reached 23 million people, who generate a demand for eleven million cubic metres of fresh water each day. The existing water resources cannot meet this demand and reservoirs are being constructed to support growth, however, leakage levels from the city’s water supply systems are also high and need to be addressed to help the challenge.

Recently the Shanghai Fengxian Waterworks Company used swagelining technology to renovate 270 m of corroded cast-iron watermain under a wooded area in the city. The new 300 mm diameter PE100 pipe with an 8 mm wall thickness was pulled through a die that reduced the diameter by approximately 10 per cent to enable it to enter the old main. Once in position, the pulling force was released and the pipe expanded to form a close-fit with the inside of the old host main. To ensure that the durability of the system was maintained BorSafe HE3490-LS-H HSCR PE100 material was used to manufacture the pipe by Jiangyin David Plastics. Projects such as this will make a major contribution to solving the water needs of many of China’s large industrial cities.

Lining Steel pipes for the mines in Australia

Sino-Steel has invested in the development of the Cape Preston Sino Iron Project for Citic Pacific Mining in Western Australia. Like most projects of this type, there is a need for the development of a huge amount of infrastructure including the installation of many kilometres of pipe for transporting water and slurries to different parts of the site. For the lower pressure pipelines PE is usually selected, but for higher pressure pipes welded steel is required, however, these need to be protected against corrosion and abrasion using a PE liner.

Kingston Bridge Engineering in Perth received an order from United Pipelines, a US-based specialist pipe lining company, for 2×30 km special-sized PE100 pipelines for close-fit lining of a 30 and 32 inch steel slurry transportation and return water pipelines. Since close-fit lining techniques can cause damage to the external surface of the pipe, HSCR BorSafe‰ã¢HE3490-LS-H material was recommended to ensure that the pipe would provide the expected life.

The pipes were extruded by Kingston Bridge and delivered to site where they were butt-welded together and then inserted into the steel pipes by United Pipelines using “÷tite liner’ technology. Before insertion, the PE pipes are drawn through a hydraulically powered roller reduction box that reduces the outside diameter of the pipe. This can then be easily pulled through the steel pipe and once in position the tension is released so the pipe can recover and form a tight compression fit with the bore of the host pipe, where it will protect this pipe from abrasion and corrosion.


Using PE pipes in combination with modern trenchless installation methods provides a new pipeline at a lower cost whilst minimising any disturbance to the life of the city or damage to the environment. The growth in the use of this technology has encouraged
PE polymer producers to strive to produce a range of HSCR PE100 materials. These materials enable engineers to exploit the benefits of trenchless technology to the maximum whilst ensuring that life of the systems should still meet their expectations.

Send this to a friend