Speed, strength and safety: Why plastic water supply systems are on the rise
Water supply systems in tall buildings can be complex, and with a growing number of modern systems with different materials and jointing methods replacing traditional copper plumbing, both specifiers and contractors face a dilemma. Here, Juan Ramiro, Design Engineer at Polypipe Building Services, weighs up the pros and cons of the available choices and explains the advantages of different installation methods.
I’m a plumber by trade and, having spent time in Europe, I noticed that plastic water supply pipework started to appear in the 90s on the continent and became pretty much standard by the turn of the millennium.
Meanwhile in the UK, copper plumbing has remained prevalent – which can be viewed as a missed opportunity for project efficiency. Every material has its pros and cons, and we will address the bigger picture of the copper versus plastic debate later. But as far as installation goes, plastic plumbing has an undisputed advantage, especially in tall buildings.
As installation windows shrink, margins for error are now smaller than ever. So, any prospective water supply system must be installed safely, accurately and efficiently to meet project deadlines. Cutting, fluxing, de-burring and soldering copper pipe joints takes time and involves hot works. Aside from the work itself, safety requirements add further time to the job, with at least 30 minutes of fire watching needed after every individual solder. Crucially given ongoing skill shortages in the sector, metal plumbing requires expertise that is increasingly difficult to find.
Plastic water supply pipes can be joined by various methods which are far easier to learn and execute. In tall buildings, several of these methods may be used at different points in the system. The large diameter pipes used for risers and headers can simply be joined using butt welding techniques, and it’s also worth noting that it can be cost effective to have any complex branches or bends fabricated off-site.
Electrofusion welding
Further along the system as the diameter of pipes decreases, electrofusion welding comes into play. In this method, joint fittings contain a sleeve with an embedded coil of resistance wire. When electrical current is applied to this wire, both the sleeve and the surface of the pipe melt and fuse to form a highly robust, watertight joint upon cooling. It takes just a few hours to learn the technique, which uses light equipment and produces joints that are just as strong as an unjointed section of pipe.
In conventional electrofusion, pipes are clamped in place until the joint has solidified on cooling to ambient temperature. Our MecFlow Fusion system also uses our patented CLICKWELD electrofusion technology, with fittings that have integrated clips which eliminate the need for clamping. This enables sections with multiple joints to be assembled prior to welding, cutting installation time by as much as 30%.
As pipe diameters reduce further, socket welding is typically used. A socket welding machine heats an element with a socket and a spigot. This enables the installer to simultaneously melt the outer surface of the pipe and the inner surface of the joint, then push them together quickly to fuse the two. As a manual technique, socket welding requires a little more skill than electrofusion jointing, but both can be learned far more quickly than soldering copper joints.
The last leg of a water supply system, often from the meter to the tap, is where plastic plumbing stretches further away from copper in terms of speed and ease of fitting. The low-diameter plastic piping used here is very lightweight and flexible. Used straight off the reel, it can be fed through awkward runs, avoiding the need for the skills, tooling and time required to bend and join multiple sections of copper piping.
Extra security
Some push-fit systems claim to require only a pipe cutter to make a watertight joint in seconds.
At Polypipe Building Services we prefer the extra security of a press-fit system to provide confidence that jointing will be up to the job. MecFlow Press system fittings incorporate a large inspection window so that installers can be sure that the pipe is inserted correctly before the joint is pressed home.
All water supply systems must be rigorously tested as part of the installation process, making sure the water system is leak-free and can withstand the required pressures and temperatures. Again, the MecFlow Press system has a ‘leak before press’ function that enables installers to identify potential leaks before a system is fully commissioned.
In my view, therefore, it’s hard to dispute that plastic pipes are easier, safer and more efficient to install than copper, as well as being significantly less expensive.
Looking at the bigger picture, copper has historically held other advantages over plastic systems in water supply applications. It is naturally biostatic, so bacteria will not grow on it, eliminating the risk of legionella and other pathogens. But plastic pipe materials can now match copper in this regard using antibacterial additives.
Copper is well recognised as being able to handle the pressure and temperature requirements of water supply applications, and now polymer systems match the performance levels of traditional materials – thanks to next generation polymers and advances such as microfibre reinforcement and multilayer construction.
High quality plastic water supply systems have the mechanical strength, together with the temperature and pressure resistance needed to perform just as well as copper, for just as long.
The huge advantages that plastic water supply systems provide when it comes to material cost, installation time and safety mean that they will surely become as popular in the UK as they are already elsewhere, especially now that the performance gap between copper and plastic has been closed in terms of mechanical strength, temperature and pressure resistance. And the fact that the shortage of skilled labour in plumbing can be offset by the simplicity of installation that polymer systems offer, especially in tall buildings, means the rise of plastic looks set to continue.
