Fourteen new plastic extruder machines have been moved to plastic pipes manufacturer DPI Plastics’ new factory in Roodekop, Johannesburg, which is next to the already existing Roodekop polyvinyl chloride (PVC) pipe factory. The extruders can produce 2 200 t/m of new high-density polyethylene (HDPE).

The factory, which was completed in March this year, was commissioned in November last year. With the new extruders, the factory can produce HDPE pipes between 16 mm and 1 000 mm in diameter, and up to nominal pressure (PN) 25 pressure class.

The new factory more than quadruples DPI Plastics’ HDPE pipe production, and the new extruders have lower maintenance costs than that of the older machines in the Bellville factory, explains DPI Plastics technical and product manager Renier Snyman.

He points out that the factory consists of an entirely separate site that required new infrastructure, such as cabling, power, water, stockyard, a laboratory and a raw materials store.

Using only approved PE 100 raw material, HDPE pipe will be manufactured in accordance with SANS 4427 (HDPE for water) and SANS 4437 (HDPE for gas). The pipes produced at the factory falls under the Durothene brand from DPI Plastics.

He points out that the Durothene pipes can handle pressure classes from 3 bar to 25 bar. Smaller pipes with a diameter of up to 110 mm are coiled in up into 100 m lengths, which eases transportation and reduces the amount of joints needed.

“Our laboratory has melt flow indexing and oxidation induction time testers to perform critical quality tests on the HDPE pipes,” explains Snyman.

He points out that the addition of the new factory enhances the manufacturing capabilities of DPI Plastics, which he says has one of the largest PVC pipe production capabilities in Africa.

“It produces PVC pipe in diameters from 50 mm up to 630 mm, and pressure classes from 4 bar to 25 bar. “This is the only factory in Africa that produces 630-mm-diameter PVC-m pipe,” he says.

DPI Plastics also has an injection-moulding factory, with 18 injection moulders ranging from 50 t to 575 t in size, and an installed capacity of 250 t a month. The factory produces PVC fittings ranging from 40 mm to 160 mm, which are also trimmed, assembled and packed on site.

Mould and machine maintenance of the injection-moulding factory are conducted by our team in the fully functional tool room, using lathes, milling machines and a spark eroder, says Snyman.

He adds that certain fitting configurations are fabricated separately through cutting and welding, while two 30 t presses fit steel Victaulic shoulders onto PVC high-impact and mining pipes.

Snyman points out that the company also reuses waste material that originates from the in-house production of HDPE pipes. The company reclaims the waste by granulating and then pelletising the waste plastic, this material is tested before being marked as acceptable for use.

He concludes that building the factory in Gauteng is a strategic manoeuvre, which reduces transportation costs. The company will now focus on improving efficiency and cost effectiveness with future growth depending on the market needs.