It is a type of flexible plastic pipe used for fluid and gas transfer and is often used to replace ageing concrete or steel mains pipelines. Made from the thermoplastic HDPE (high-density polyethylene), its high level of impermeability and strong molecular bond make it suitable for high pressure pipelines. HDPE pipe is used across the globe for applications such as water mains, gas mains, sewer mains, slurry transfer lines, rural irrigation, fire system supply lines, electrical and communications conduit, and storm water and drainage pipes.
PE refers to the grade of the HDPE resin used for manufacturing the HDPE pipe. It’s basically Material of construction. PN refers to the pressuring rating of the pipe. PN 6 means the pipe is suitable for 6 Kgf/Cm2 of pressure.
High density polyethylene – HDPE – is a very popular material for water pipes. It is
- Resistant To Chemicals
- Easy And Light Weighted
- Long Living
- Low Friction
- Relatively Cheap
- Sun Resistant
PE pipes can be used in range of temperatures -40 oC to 60 oC considering the change of operating pressure. Typically the standard specification identifies class of a HDPE pipe is by the nominal pressure class – PN – up to PN 20 or 20 bar. HDPE pipe can also be classified by the material used – PE 100, PE 80, PE63, PE 40 or PE 32.
PRESSURE NOMINAL – PN
PE pipes are produced in different pressure grades (PN grades), which indicates the pressure in bars the pipe can support with water at 20 oC.
The pressure grades available
- PN 2.5 – max pressure 2.5 bar
- PN 4 – max pressure 4 bar
- PN 6 – max pressure 6 bar
- PN 8 – max pressure 8 bar
- PN 10 – max pressure 10 bar
- PN 12.5 – max pressure 2.5 bar
1 bar = 105 Pa (N/m2) = 0.1 N/mm2 = 10,197 kp/m2 = 10.20 m H2O = 0.9869 atm = 14.50 psi (lbf/in2) = 106 dyn/cm2 = 750 mmHg
CLASSED BY MATERIALS
Polyethylene pipes are also classified by the type of material used:
- PE 63 – medium pressure piping systems – irrigation system – drinking water connections
- PE 80 – gas pipe for natural gas distribution network with pressure rate up to 4 bars- drinking Water pipe with pressure rate up to 16 bar – sewers, outfall pipes, industrial pipes
- PE 100 – high demands piping applications
COLOR CODES AND MATERIALS CLASSIFICATIONS
Common colors used to classify the pipes
- completely black for industrial applications
- completely blue or black with blue stripes, fro potable water
- completely yellow or black with yellow stripes, for gas conduits
Note that the colors may depend on country.
- Quick Installation – Due to its lightness, the transportation, handling and installation process is shortened. Besides, it doesn’t need heavy machine to move it.
- Flexibility – They are adapted to changes of direction and bends, so they don’t do fittings or additional tools. In comparison, it is more flexible than the polyethylene.
- Resistance – They support vertical loads due to they transfer the higher part of the load to the soil which is around the pipe. This is due to its corrugated external wall.
- Useful life – They are resistant to the effects of the abrasive liquids, to impacts and to other chemical agents; the useful life of the HDPE pipes is estimated of 50 years.
- Safety – They are not used together as the welding is done by thermo fusion welding, with which the safety of the installation is complete.
- Efficiency – Due to its flat inside part, they facilitate a flow of liquids to the pipes of other materials. Besides, they don’t accumulate sediments or incrustations inside them.