With different ranges, specifications and standards of plastic pipe, it is sometimes difficult to decide which system is best for you. The table below gives some information about the individual types of plastic pipe system along with a link to more information:

System Type

PVC Inch Pressure Pipe Systems

PVC Sch40 Pressure Pipe Systems

PVC Metric Pressure Pipe Systems

PVC Clear Pipe Systems

ABS Pressure Pipe Systems

CPVC Pressure Pipe Systems

PVC Ventilation Systems

PPS Ventilation Systems

MDPE and Compression Systems

Furniture Grade

Uses

Most older PVC pressure pipe systems in the UK are installed in inch sizes, as before the 1990s that was all that was available. More recently, however, metric systems have been gaining popularity as there is a wider range of fittings available. It is recommended that expansions to existing inch systems are carried out using inch sizes to avoid confusion. Inch PVC pressure pipe is typically used in process lines in factories, swimming pools and aquaculture. PVC pipe is very easy for non-skilled workers to install, with no special tools and only a small amount of training required.

With the exception of 2 ½", all plastic pipe sizes in the North American Schedule 40 and Schedule 80 pipe systems are compatible with the inch sizes you will find in the UK, so the fittings and pipe are interchangeable. The exception is where threads are involved; the North American systems will generally use NPT threads, which are not compatible with the BSP threads used in the UK and Europe. Applications for Sch40 pipe are much the same as above; however, as it is manufactured in white PVC as standard, some installers prefer to use it in high hygiene and food processing applications, as it is easier to notice dirt build up. As with the inch sizes above, Sch40 pipe is solvent welded and so easy and quick to install.

The use of metric PVC in the UK is a relatively recent occurence and started primarily because of the irrigation industry, for which many parts came from Europe. It is now firmly established in the UK and accounts for about 50% of all new PVC pipe systems installed. Still the standard of choice in agriculture and irrigation, it finds favour in many other applications (process lines, water treatment, fish farming etc.) because it has a larger range of sizes and also a wider range of fittings available. The solvent weld process of connection for metric PVC pipe makes installation very fast and straight forward.

Clear plastic pipe systems are only available in PVC material. At present, only the inch sizes have a range of fittings available to match, with metric availability being limited to pipe only. Metric clear pipe is substantially cheaper than inch sizes as it is manufactured in options with thinner walls, which means less material needs used and so the cost is lowered. Clear plastic pipe is most often used for viewing liquids in process, building demonstration units or as sight glasses. Like all PVC plastic pipe, the clear pipe is built using a painted-on cement to both the pipe and socket, although care must be taken not to let cleaner or glue splash or run down the pipe as it will affect the clarity.

As well as having a different chemical compatibility profile to PVC, ABS has a different ductility profile. This makes it the plastic pipe of choice for systems that use a cold or below freezing fluid, such as glycol circuits, ice cream factories and ice slurries in fish plants, as the pipe is far more robust than PVC at these temperatures. ABS is also often used in the brewing industry. If required, ABS can be cemented to PVC as long as PVC pipe cement is used; however, our recommendation for this type of join would be maximum pressure of half that of the normal working pressure.

CPVC or Corzan is used where plastic pipe is required and the temperature is higher than that which can be handled by PVC or ABS (60°C and 70°C respectively). CPVC will handle up to 85°C and even as high as 95°C for short periods. CPVC also has a higher chemical resistance than standard PVC and so is used in harsh applications. Installation is by solvent weld. Threads are advised to be kept to a minimum. This is because plastic pipe has a coefficient of expansion two to three times higher than metal pipes, and so when the temperature of a CPVC system is heated up or cooled, seals in threaded connections can break, leading to leaking.

This is a system of thin-walled, large diameter plastic pipe and is used for ventilation and ducting in areas where there is a high risk of corrosion of standard galvanised spiral ducting. Applications include swimming pools, public aquariums, shipping and clean room facilities. The lightweight nature of this pipe and its ability to be easily painted also make it a favourite for set design and prop construction. Joining of PVC vent pipe is by solvent weld or flanges, although some installers prefer to hot air plastic weld it.

PPS is often confusing and people think it is an abbreviation for a type of polypropylene, but in fact it is polyphenylene sulfide, which has very different properties. Its advantages over PVC for ventilation and ducting are that it has a much higher operating temperature (200°C as opposed to 60°C) and it does not build up static electricity. The latter of these makes it the material of choice for the semiconductor and aerospace industries, where it is most widely used. Other uses include industrial fume extraction. Unlike PVC, PPS cannot be joined by solvent welding and most installers use silicone or other mastic products.

Supplied in either blue or black, only the blue pipe has a WRAS approval for potable (drinking) water. MDPE is the choice plastic pipe for long runs of small-bore pipe <63mm. It is supplied in coils and is very tough, meaning that it can be buried. It is the main type of plastic pipe used in domestic water supply in the UK. A limitation of all types of PE pipe is that it cannot be cemented or glued, so compression fittings must be used. The compression fittings are much longer than an equivalent PVC or ABS pipe fitting and this, combined with the higher flexibility of the pipe, makes it unsuitable for more complex pipe arrangements.

This is a specially manufactured PVC using a formula that greatly increases the ductility of the plastic pipe and fittings, making it shatter proof and strong enough to build structures and furniture from. It is not suited to applications for fluid transfer as the fittings are not pressure rated or tested to WRAS drinking water conformity.