Plumbing 101: A Guide to Poly Pipe and Poly Pipe Fittings

Plumbing revolves around pipes and the right fittings. Pipes or tubing are what get water to and from your home or business, and fittings are used to control and distribute the flow of water within the plumbing system. Choosing what’s needed for your next DIY plumbing project can be confusing. First, there are differences in the types of plumbing. Potable systems for instance are responsible for drinkable or potable water and that which is appropriate for human consumption. Sanitary piping or plumbing removes human waste and wastewater products into the sewage system, and stormwater systems are what redirect rain and precipitation to another area.  

Most plumbers will be concerned with potable plumbing systems. And here pipes and fittings vary according to usage, water flow, and the materials they’re made of. Different metals have been used throughout the years, with lead being an infamous and toxic example, but where rigidity, strength, resistance to temperature extremes, and low corrosion rates are important, brass and copper seem to be sound choices.

For large-scale plumbing, these materials do however pose some problems. First is the high cost, and then the work and time needed in installation and fitting. The rise of plastic piping options over the last few decades has resolved these issues and plastics feature in the majority of new plumbing projects. 

What is Poly Pipe? 

Man using poly pipe fitting for underground pipes

Poly pipe (PE) is made of high-density polyethylene (HDPE), a thermoplastic ethylene polymer. It has been made in Australia since the 1950s and was first used in small-scale rural and irrigation piping, as well as in minor industrial applications. Compared to other traditional piping materials, such as PVC and concrete piping, poly pipe exhibits high durability and impact strength, abrasion, chemical and weathering resistance, good flexibility, and with the right poly pipe fittings, quick and easy installation. These properties have extended the use of the poly pipe, and today we see it used in residential water and gas supply, irrigation, sewage and treatment plants, mining and industrial piping, telecommunications and power cable routing (conduit) and more.  

Benefits of Poly Pipe 

Man using different double poly pipe fitting on underground pipe

Poly pipe plumbing owes its popularity to a multitude of benefits:  

  • Cost – PE is way cheaper than copper straight off the shelf, and any required maintenance or repair work is cheaper too, with less spent on labour. The same goes for installation costs. Since Poly pipe is quicker to install, you’ll be paying your plumber less.  
  • Simplified Handling, Transporation and Installation – Poly pipe is flexible, often bundled in spools, and this is how it’s transported. The light weight means it’s easy to handle. And being bendable and easy to cut to size, it’s much quicker to run in any plumbing project. This also means that there are fewer fittings required and these are installed with no expensive or specialty tools.  
  • High Durability and Longevity Once Installed – With the correct installation, poly pipes won’t succumb to the downfalls of other plastic or copper piping and fittings. This means that they won’t have any sort of scale buildups like in copper piping, or instances of corrosion. Water quality is better as a result and persistent over the lifetime of poly pipe, rated at 50 years.  
  • The main benefit over PVC and copper pipe is owed to its flexibility and expandability, and though freezing temperatures are rare in Australia when this does occur, homeowners can count on poly pipe not to burst or leak.  
  • Eco-friendly and Safe– Besides being cost-effective, HDPE piping is straightforward to recycle. The eco and safety benefits also relate to safer joining, with no toxic or hazardous gases released during soldering or welding. In addition, poly pipe uses less energy to make. 
  • Seamless and Leak-free Joints – Heat fusion is used in creating leak-free joints and this is where poly pipe and poly pipe fittings have a considerable advantage over metal piping.  
  • Strength and Fatigue Resistance – PE pipes retain remarkable strength, making them suitable for a range of applications, and also exhibit extremely low fatigue resistance so can comfortably handle higher water pressure.  
  • Non-corrosive – Plastic piping won’t corrode or rot under any conditions. This helps with water quality, especially resisting the growth of bacteria or mould as can happen with metal pipes and fittings.  

Range of Fittings 

Range of poly pipe fittings
Source: senpupipe.en

Controlling the flow of water within a system is done with pipe fittings. There are dozens of different fittings and each with a different task. Plumping sourced in a poly pipe is best paired with the appropriate poly pipe fittings to distribute and manipulate water within households, businesses and commercial premises. Fittings sourced in PE can also be paired with some copper piping and fittings.  

Poly Adapters 

Adapters are used to extend runs or change the type of connection at the end, allowing for connecting pipes of different types. Adaptors with male ends are used to connect to a pipe length with a female-threaded valve or tap, or in cases with there’s a planned extension to the system, with a female end cap. The same applies to female adaptors used to connect to piping with male ends. Common sizes for both are 20, 25, 32, and 40mm for household use, and all the way up to 110mm for large-scale industrial or agricultural applications. Adapters can be used with or without bushings. 

Poly Couplings 

Couplings are used for two main purposes. To extend the run of a pipe in the same size, or to connect pipes of different sizes. For this reason, they are also called pipe joiners. Some poly couplings can also join poly pipe and copper piping. Couplings are optioned in the familiar pipe sizes, but the largest can reach 160mm in diameter. A similar function is performed by unions. 

Poly Elbows 

Elbows are used to change the direction of the flow of water and piping. They come in 45- and 90-degree angles, with some unusual variants at 22.5, 30, and 60 degrees. Elbows can be sweated or threaded, with male and female threads.  

Poly Tees and Crosses 

Where there is the need for more than one branch of piping, tees and crosses come into the picture. Tees have 3 openings and crosses have 4 (making crosses a combination of 2 tees). Openings can be in the same or different diameters, affecting water pressure.  

Poly fittings retain all the benefits of poly pipes, being non-corrosive, chemical resistant, durable, and with high strength. All are capable to work flawlessly under very high water pressure, up to 16 bar (1600 kPa). 

Twenty years from now you will be more disappointed by the things that you didn’t do than by the ones you did do.