What's in the pipeline?

Dave Gray reports on the latest developments from plastic pipe extruders and their suppliers.

It’s an uncomfortable truth that 40% of waste plastic used in construction sites ends up in landfill. Polypipe Building Services is one of the UK’s manufacturers that is aiming to turn the tide on that, with a new recycling service that was trialled recently with plumbing trade merchant Wolseley UK.

In fact, the trial has been so successful that it’s now being rolled out across 11 of Wolseley’s branches in the UK. The trial began in three of the group’s branches in Brimsdown, Trafford and West Bromwich. Since January last year, Polypipe says it has collected more than 2,700 kilos of recycled waste. Polypipes drivers drop off empty collapsible pallets to the merchants they supply, which can be filled with PVC piping offcuts, obsolete products, plastic packaging, and bulk bags, and will pick the full ones up on their next delivery to the branch.

Alex Ashton, environmental & sustainability manager at Polypipe Building Services, said: “This scheme ties into our strategy of using more recycled materials in our processes following the release of our Terrain PVC sustainable pipe last year which is manufactured from up to 65% recycled PVC-u and is helping us to hit our targets as part of the Genuit group, which is committed to using more than 60% of recycled materials in our products.“Plastic often gets a bad name when it comes to the environment, but when it’s used responsibly it can be recycled again and again helping us to limit the resources we take out of the earth.”

Cardboard, wooden pallets and plastic bottles are already recycled at Polypipe Building Services headquarters in Aylesford, and recycling bags are also supplied by Polypipe to building sites they supply, so any offcuts can be collected and recycled instead of going to landfill. He added: “We’ve already had interest in the trial from several of our other distributors as it really is a win-win for them, their customers and our environment, and we have employed two dedicated recycling staff to sort all the different recycling streams.”Luchiana Laza, category manager at Wolseley, added: “We have weekly deliveries from Polypipe so the volume of waste which we can now recycle means this scheme also makes good financial sense due to the cost saving on skips.”

Polypropylene random copolymer (PP-R) pipes, and the later generation PP-RCT (polypropylene random copolymer with modified crystallinity and temperature resistance) pipes, have become increasingly popular in recent years due to their superior chemical and mechanical properties, versus older materials. A comparatively low environmental impact means they have been used more and more in the construction of hot and cold water distribution and water purification systems, in heating systems, inthe transport of compressed air, but also for the transport of chemical fluids.

Responding to the trend, pipe extrusion machinery group Bausano has now developed extrusion lines dedicated to PP-R and PP-RCT mono and multilayer pipes.

Low thermal conductivity is a key benefit of PP-R pipes, resulting in reduced heat loss or heat gain when transferring hot or cold fluids. They also exhibit strong resistance, even under changing environmental conditions, with a temperature range of 20°C to 95°C, as well as being able to withstand abrasion by solid particles, aggressive chemicals and alkaline solutions. As a result, PP-R pipes can remain functional for over fifty years. Smooth internal surfaces also make for a lower coefficient of friction, further contributing to system efficiency. 

In multilayer PP-R pipes, the intermediate layer consists of a glass fibrecompound, which further increases the pipe's strength and limits its thermal expansion. They’re also non-toxic, and less prone to electrolysis. Each of Bausano’s new lines consists of one or more single-screw extruders, equipped with a specially designed screw, and optimised melt plasticisation. 

Calibration and cooling benches, made of stainless steel, are designed to give effective cooling, providing a flawless surface. The other components of the new lines are the drive systems for a continuous, vibration-free drive, the cutting unit and the packagingwrapper.

 The latter is an automatic system, capable of forming bundles of pipes of the predeterminednumber, from 16-125mm in diameter and from 1-6m in length. The machines also come with Bausano’s ‘Digital Extruder Control 4.0’ for process control and data analysis.

"The combination of superior performance and lower raw material costs is leading to the increasing useof PP-R pipes, replacing the less efficient metal pipes," said Massimiliano Fenili, Bausano's technical manager. He added: "For this reason, at Bausano we have been specialising for some time in the design of dedicated extrusion lines that can meet the most challenging requirements of our customers. 

Thegoal we constantly keep in mind is in fact to offer a complete solution, aimed at guaranteeing maximum results and designed down to the smallest detail to optimally process the chosen material, with particular regard to its rheological behaviour. 

The inclusion of the gravimetric dosing unit, which provides interesting data on the amount of plastic processed, combined with downstream automation such as the bar wrapper, testifies to our commitment to customising our technology to specific production requirements.”In tooling, US player Guill Tool recently announced the availability of a spiderless pipe die. The firm says this die configuration increases material savings compared to conventional basket dies for pipe extrusion.

Designed to be used by tube and pipe producers for larger diameter capabilities, this new pipe die is capable of providing a finished extrusion with OD from 2”-15”. It’s offered in 4140 steel or stainless with heat treating.

In general, according to Guill Tool, material costs can range from 50% to 70% of the total cost of polymer pipe production. Increasing energy and labour costs also contribute to a need for pipe extruders to make savings in their process. The precision nature of the spiderless die means it should cut materials costs for processors, according to the firm.