Perfect fit

Demand for more user-friendly, efficient, durable and sustainable pipe systems has driven innovation over the past decade. Key trends include the rise of smart plumbing systems, the increased use of advanced materials such as PEX and stainless steel, and a focus on sustainability and water conservation.

“With continued innovation in materials and installation methods, installers have access to a range of pipe materials, each with advantages,” says Jack Young, regional sales manager at Mueller Europe.

The main types of pipe materials in use today include copper, galvanized steel, polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), cross-linked polyethylene (PEX) and chlorinated polyvinyl chloride (CPVC).

“At a basic level, the choice comes down to plastic or metal, although materials within each category offer some variety on performance, cost or ease of installation,” says Antony Corbett, product applications engineer at Geberit. “It’s common for installers to stick with what they know, but our advice is always to be open to new ways of working.

“Faced with the challenge of balancing increasingly stringent efficiency targets with ever-squeezed budgets, it is inevitable that some systems will be repackaged again and again, because they work at the right cost, without impacting efficiency. Many installers still use what they know, even if that means missing out on installation efficiencies.”

Metal piping

“It’s difficult to accurately compare the cost of metal pipes, not least because of the volatility in the price of raw materials,” says Corbett. “Copper is liable to price fluctuations, while carbon steel is more stable. We should also factor in manufacturing costs, particularly for stainless steel, which requires more work to make it into the right pipe.”

Sustainability is also a consideration for many businesses and homeowners, which is why copper is popular. Not only is it recyclable, but it is favourable due to its thermal resilience and ability to withstand fluctuating temperatures.

“Copper is suitable for supplying heating, water and gas into homes,” says a spokesperson for the Copper Sustainability Partnership. “As an excellent conductor of heat, it allows for rapid and efficient heat transfer, making it the standout choice for supplying the heat generated by low-carbon systems.

“Copper pipes can be integrated with air-source heat pumps, transporting the heat extracted from outside air to radiators, electric heaters and other outlets. As well as improving efficiency, copper pipes are also infinitely recyclable, helping to reduce carbon emissions associated with the design of air-source heat pumps.”

It’s because of these variants that installers are encouraged to consider the whole project cost as opposed to just the cost of the pipes. Innovations include press-fit technology, which offers time-efficient and therefore cost-effective installation while improving safety, as there is no need for soldering or lengthy cooling down periods. All these factors bring down the overall cost of installation and therefore the project as a whole.

“Another benefit of press fit is the reliability of connections,” points out Corbett. “The simple process involves cutting the pipe to size, deburring the inside and outside, marking the socket insertion depth on the pipe and pushing the pipe into the socket of the fitting, before pressing the joint and connecting pipe together. Coloured pressing indicators are fitted around the ends of fittings, which offer easy identification of both the material and any unpressed joints during the installation process. What’s more, the fitting and pipe are pressed only once the pipe has been inserted to the required insertion depth, which ensures a safe, dependable and long-lasting connection. There is no need for lubrication and the joints will leak until pressed to show incomplete pressing during pressure testing.”

Plastic piping

According to the British Plastics Federation (BPF) Pipe Group, plastic piping contributes to sustainability and the circular economy through its energy-saving potential, recyclability and energy recovery options.

When it comes to plastic, installers can choose from polyethylene (PE), polybutylene (PB), polypropylene (PP), acrylonitrile butadiene styrene (ABS) and polyvinyl chloride (PVC), each with differing levels of hardness and chemical resistance to suit a range of applications.

“In general, plastic pipes are more lightweight than metal, with a smooth bore and are less susceptible to corrosion,” says Corbett. “Push-fit plastic pipes are easier to connect than soldered metal pipes of course, but the development of press-fit technology for metal pipes and the need for welding on some plastic drainage piping systems should be considered in any debate over speed and ease of installation.”

When it comes to drainage, high-density polyethylene (HDPE) is a common choice, according to Geberit, as it combines the lightweight flexibility and installation benefits of plastic pipes with the robust, durable properties required for commercial applications. Although HDPE isn’t as cheap as other plastics, the initial investment is balanced by reduced maintenance costs and an extended system lifecycle, in addition to the peace of mind that comes with a strong and reliable welded solution.

“HDPE pipes have a smooth bore which is maintained throughout their lifetime, helping to repel any waste that might attach to the inside, and they are reasonably hydrophobic – the interior of a HDPE pipe can often be cleaned simply by flushing the toilet or running the tap,” adds Corbett.

Although PVC offers similar properties for a lower price, it is a relatively brittle material, particularly in cold weather, and doesn’t provide strong acoustic performance, so lagging is often required with extra time and cost implications.

Enhanced polypropylene (PP) composite is comparable in price to PVC pipes and fittings, more robust than PVC and has a strong acoustic performance due to its enhanced structure. This can deliver overall cost savings compared to lagged PVC by reducing or removing the need for lagging.

Multi-layer piping

Multi-layer pipes are increasingly popular due to the installation benefits, their flexibility and durability. This type of piping comprises an outer plastic layer made of polyethylene (PE-RT), which protects against corrosion and mechanical damage. Installers should look for sustainable options that use second-generation PE-RT. They contain a central aluminium layer, which makes the pipe stable yet bendable, and an inner layer, also made of PE-RT, for internal corrosion resistance.

“The technology has been often reserved for industrial applications but it also offers a single solution for all potable water and heating supplies on both domestic and light commercial projects,” says Corbett. “The central-welded aluminium layer offers mechanical stability to ensure that the pipe remains in its required position yet remains flexible enough to bend. The aluminium layer also provides an oxygen barrier, making it suitable for use in central heating systems, and makes the pipe detectable by electronic devices after installation.”

As part of its long-term plan for housing, the government is consulting on proposals to strengthen planning policy for brownfield developments. When developing brownfield sites, care needs to be taken to protect water supplies from contamination.

“Polyethylene pipes with an aluminium barrier are routinely used in brownfield applications where potable water needs protecting from possible contaminants in the ground,” explains Caroline Ayres, director of BPF Pipes Group. “They are especially useful in larger developments as their longer lengths minimise the number of joints needed.”

The BPF Pipes Group has published guidance on laying the appropriate types of pipes and fittings in such ground and emphasises the importance of specifying and installing such products correctly.

“BS 8588: 2017 is the industry standard for polyethylene piping systems with an aluminium layer,” explains Ayres. “It confirms through testing that a pipe and fitting in combination successfully act as a barrier to organic contaminants, ensuring that concentrations remain below a threshold to protect drinking water quality. Fittings for connection of PE barrier pipes shall comply with WIS 4-32-11: 2018 up to 63mm diameter or BS 8561: 2021 for large sizes. Both pipe and fitting need to be mechanically sound and together be capable of delivering a leak-tight system over the product lifetime. So, to fully comply with BS 8588, manufacturers need to declare the combinations of pipes, fittings and fusion joints which have been proven to meet this standard.

“The true benefit of installing these barrier systems is peace of mind for water suppliers and consumers when it comes to the quality of water at the tap. Integrity of the barrier to contamination is assessed through the test for resistance to permeation, which is designed to demonstrate that components in a system can together adequately resist the ingress of hydrocarbon contaminants.”

When specifying piping, installers should ensure compliance with regulations by purchasing from a member of the BPF Pipes Group, as its products have been awarded a BSI Kitemark. Products offered by members also comply with Water Regulations, ensuring public health is protected.

• Plastic piping systems and water fittings regulations and bylaws can be found at bpfpipesgroup.com

Check compliance

The BPF Pipes Group recommends using fittings that have been fully assessed and certified by a third party, such as the BSI Kitemark, to WIS 4-32-11 or BS 8561.

“Where certification is not available, specifiers are advised to check that all tests included in the specification have been completed,” says Ayres. It also strongly encourages those specifying these types of pipes and fittings to check that permeation testing under BS 8588 has been carried out to the actual pipe and fitting combination being offered, and to check that mechanical performance has been fully assessed to WIS 4-32-11 or BS 8561, using the fittings and barrier pipe for which they are being offered.

The BPF Pipes Group strives to promote best practice in the construction and use of all types of plastic pipes and fittings and its website contains many free-to-access technical guides and practical guidance: bpfpipesgroup.com/technical-information/overview