High Density Polyethylene pipe (HDPE)
High Density Polyethylene pipe (HDPE) is currently the most common type of piping used for sewer lateral pipe bursting replacement. It characteristics lend itself well to sewer laterals because it is strong, semi flexible and has no mechanical or glued joints (it is heat welded) for a watertight and root impervious lateral. It is also chemical resistant and very resistant to breakage.
The usual method for installation is “trenchless” technology where a cable is fished through your old lateral and a bursting head breaks away your old lateral. A pit is dug at the exterior of your house and at the city main. A new one-piece HDPE pipe is pulled behind the bursting head and is installed simultaneously. The disturbance to the landscape/hardscape is kept to a minimum.
Benefits
The toughness and resistance to chemicals of polyethylene, as well as the corrosion resistance and low weight have contributed to its growing use in situations where cost-effective and durable fluid and gas piping systems are required. According to a press release from the Plastics Pipe Institute, “PE piping has been used for water and other fluids in Europe and America since the 1950s due to its durability, leak free joints, resistance to corrosion, and long-term cost-effectiveness.”
HDPE pipe can be joined by butt welding, electrofusion welding, socket welding, or extrusion welding. These joints heat the pipe during the joining process, creating a completely homogeneous joint so the weld becomes as strong, or stronger than the existing pipe on either side of the weld. There is no need to use rubber seals or jointing chemicals, as is used for joining PVC pipe, which cause environmental health issues and increase the chance of failure over time. PE is less likely to have problems with root intrusion, and provides integrity for the pipeline, even when installed in unstable soils.
HDPE pipe is very durable and flexible and can be bent on site to a radius twenty-five times the nominal pipe diameter – for SDR11 and SDR17 pipe, at or below 20°C ambient temperature. This provides major cost savings, when compared to different pipe systems, some of which require glued fittings, restraints or thrust blocks for even minor changes in direction. Because of the high impact resistance and flexibility of HDPE pipe, it is well suited to installation in dynamic soils including in earthquake-prone areas. HDPE pipe has very high flow capacity, because of its smooth bore and end-to-end jointing methods. HDPE pipe does not corrode in the environment, and will maintain its flow capabilities over time, unlike ferrous piping systems, which will rust and build up internal resistance to fluid flowing through it.
Because food-grade polyethylene virgin material is used to fabricate HDPE pipes, they are safe for the transfer of drinking water, provided that any initial debris has been flushed out. HDPE pipe is resistant to many chemicals, facilitating its use in process plants or around corrosive or acidic environments, without needing to use protective coatings or galvanising, as is required on steel pipes. As HDPE has a very low thermal conductivity, it can maintain more uniform temperatures compared to metal pipes when carrying fluids, which will greatly reduce any need for insulation to control condensation around the pipeline.