Pipefitting systems manufacturer DPI Plastics has been prompted to expand its polyvinyl chloride (PVC) Ultralok range to include larger diameter couplings, owing to the popularity of this range in mining and civil engineering applications.

The company will introduce new 155 mm and 160 mm PVC Ultralok couplings to the South African mining industry next month and will introduce 200 mm and 210 mm couplings to the market in April next year.

“Ultralok, which was previously only available in 110 mm and 105 mm diameters, is a patented product for the jointing of plain-ended pipes,” says DPI Plastics technical product manager Renier Snyman.

He points out that Ultralok can be used as repair coup-lings, or for primary joints, in mining and civil pressure pipelines, as the range can be used with high-pressure PVC or high-density poly-ethylene (HDPE) pipelines of up to 16 bar.

“Ultralok is cost effective when compared with standard couplings that are currently on the market. The couplings are made from PVC, which is less expensive than couplings that are traditionally made from galvanised steel or stainless steel,” explains Snyman.

He notes that DPI Plastics originally developed the Ultralok PVC couplings in mid-2012 in response to requests from its clients in the mining industry that were experiencing substantial and costly damage to their metal pipelines as a result of sulphate-reducing bacteria (SRB) in the water.

“When the metal pipes are exposed to sulphate-containing water, the interaction of water and metal creates a layer of molecular hydrogen on the metal surface. SRB then oxidises the hydrogen while creating hydrogen sulphide, which causes severe corrosion,” he says.

Snyman highlights that the Ultralok system is fully protected against corrosion.

“The lightweight, high-strength, low-reactiv- ity, fire properties and corrosion resistance of PVC as a material makes it far better suited to heavy-duty and highly-abrasive mining applications,” he states.

Snyman adds that the design mechanism of Ultralok is unique in terms of its robustness and gripping capabilities and incorporates a pressure-enhancing rubber seal.

“As the pressure increases, the design of the seal facilitates a distributed load, thereby alleviating the tensile load on the body of the coupling,” he points out.

Further, Snyman mentions that Ultralok is manufactured in-house by DPI Plastics and is performance tested to the company’s stringent internal specifications to meet all criteria for use in 16-bar pressure pipelines, where fully restrained joints are required.

He says the Ultralok PVC range has suc-cessfully met a one-hour test at 54.50 bar, a ten-hour test at 50.60 bar, a 100-hour test at 45.50 bar and a 1 000-hour test at 16 bar, all at 60 °C.

Although Ultralok has predominantly been used in mining applications, Snyman states that the product is gaining ground in the civil engineering market. He is confident that the extended range of larger diameter couplings will lead to increased sales in this sector.

“We have sold a substantial amount of Ultralok couplings, particularly for use in new potable water reticulation pipelines. As more money is invested in larger pipeline projects, the demand for the new diameter couplings will increase substantially in the long term,” he adds.

Snyman notes that DPI Plastics will be promoting the benefits of the new Ultralok range through various trade shows, publica-tions and industry word-of-mouth.

“The South African couplings market is currently looking stable and the promotion of DPI Plastics’ reliability will contribute significantly towards sustaining future market share,” he concludes.