New design opens more doors for pipe manufacturers

Amid government spend on big water projects and the ongoing, urgent need for water infrastructure development, pipes manufacturer DPI Plastics’ latest addition to its existing 630-mm-diameter range, the new 630 Class 16 modified polyvinyl chloride (mPVC) pipe, has enabled the company to make significant inroads into the bulk water infrastructure market.

“The construction industry is currently stagnant . . . but when one looks at infrastructure and the provision of bulk water, it has been ongoing for the past eight months, and that has presented opportunities for us. If this continues . . . with big projects breaking ground across the country, our business will continue benefiting,” comments DPI Plastics MD Juan Muller.

DPI Plastics technical and product manager Renier Snyman comments that the company’s new mPVC pipe, as well as having supplied technology licences to customers in Australia, Asia and South America, has confirmed it as an innovator and international market leader.

Snyman highlights that the company was the first South African manufacturer of mPVC piping systems in the 1990s, adding that all mPVC pipes are manufactured in accordance with SANS 966.

Pressure Testing

He asserts that DPI Plastics has also developed a ‘how to’ guide on field pressure testing to ensure that the integrity of a pipeline is not compromised. Field pressure testing establishes that the pipeline does not leak.

“A field pressure test is used to test the integrity of pipe joints completed on site. This test is covered by the SANS 2001:DP2 – Medium pressure pipelines standard,” explains Snyman.

He notes that modern plastic pipes are manufactured under controlled conditions, with hydrostatic pressure testing of pipes and joints to confirm minimum performance requirements.

However, he points out that, when the pipe is laid on site, the jointing quality and method are outside the control of the manufacturer.

The test pressure is thus raised above the operating pressure of the pipeline to allow the pipeline to settle under that pressure and to highlight possible leaks that would otherwise only develop after some time under pressure.

Design Specifications

Snyman explains that the mPVC has thus been designed specifically to provide similar tensile strength and greater resilience than standard PVC piping products. It is ideally suited to bulk water supply projects, owing to mPVC being considerably more ductile than industry-standard unplasticised polyvinyl chloride (uPVC).

He adds that mPVC is more beneficial than uPVC, as mPVC has thinner walls for the same pressure class. It is, therefore, easier to manufacture a 630 Class 16 mPVC pipe than a Class 16 uPVC pipe because thick walls are difficult to manufacture. Reduced wall thickness translates into using fewer raw materials during the manufacturing process and, ultimately, a lighter product that is easier to transport and install, thereby minimising its total carbon footprint.

Further, he asserts that the ductility of mPVC pipe provides it with exceptional resistance to crack propagation under pressure, in addition to superior toughness.

DPI Plastics produces mPVC pipe in pressure classes from 6 bar to 25 bar and in standard
6 m lengths, complete with spigot, integral socket and rubber ring seal for ease of installation, Snyman adds.

He highlights that the increased demand for mPVC piping systems is due to its suitability for large-bore water infrastructure projects, which are popular in the current market.