machinery | Large diameter pipe
system. Thanks to the new spiral geometry design, low pressure and high melt distribution is achieved, while the inside heating/cooling unit ensures uniform temperature control and distribution. The Tecnomatic die-heads, for large diameter pipes,
are compact and short in length and the working system is based on a swelling production process. Properly sized die-sets allow also an easy and quick disassembling and cleaning. The main advantages of two-spiral die head
Above: Krah says that its KR800-Max production line has made
2,000mm pipe at an output of 1,400kg/hour
numerous pipe sizes (in various stiffnesses and SDR classes), with changeover times of less than 10 minutes.
Big head Tecnomatic has designed a special die head that allows the production of polyethylene (PE) pipe up to 2,600mm diameter – with hourly throughputs of 3 tonnes of material. Each Venus die head features two spiral distributors,
and is fed by two extruders. High output extruders are limited in their availability and reliability, says Tecno- matic, which is why it designed the pipe heads to work with two single-screw extruders. In this arrangement, both extruders should have high capacities, identical size and be equipped and synchronised with an accurate dosing system to ensure correct weight control. This procedure increases line productivity and
ensures fast pipe turnaround times due to increased production capacity, says the company. Its Venus 1600 and 2600 pipe heads are designed to
Right: Tecnomatic’s
Venus die head is fed by two
extruders, and produces PE pipe up to 2,600mm in diameter
process PE100 material. Each pipe head has two spirals inside, with the same geometry. The system is comparable to a co-extrusion die, says Tecon- matic.
The melt distribution system is short in
length and low in volume, ensuring short residence times. A gap in the centre allows air exchange inside the pipe at high volume. Melt feed points are
horizontally positioned and allow a parallel arrangement of the extruders – leaving enough space for the ducts of the pipe air cooling
40 PIPE & PROFILE EXTRUSION | July/August 2017
technology include: high output; low material shear at high output; ideal temperature distribution inside the head, thanks to an optimal tempering system; short head dimension; smaller basic head – and bigger die – to make the volume low and residence time short; and, inner pipe air cooling. A key point of the project was to boost output rate at
lower melt temperatures and power consumption. This has been achieved by using a spiral grooved feed bush and improvements in screw design. The new feed bush ensures minor friction, commonly generated by raw material transport. Developments in the screw design – with optimisation and enhancement of torque and shearing elements – have improved the output while allowing the material to be processed at lower melt temperatures. Using two extruders in the Zephyr series, in size 75
or 90, allows the production of pipes at rates up to 3,000kg/hour.
World first Agru has claimed a world first by installing PE100 pipe – with outside diameters of 1,200 and 1,400mm – using horizontal direct drilling (HDD). The Agruline PE pipelines were installed trenchless, in a twin-pipe culvert underneath the River Spree in Germany. The pipe is used to transport groundwater – as well as water from a nearby open cast coal mine.
These pipes were originally made from GRP, but these had undergone complex repair – and could, at a later date, suffer further damage. As the coal mine can only operate for
a few days without the pipeline – which is used to lower the water table – the switch was made to PE100. A new installation using HDD with pipes made from PE 100-RC was the most
economic and easiest solution to imple-
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