Polyethylene PipeBesides being leak free, PE pipe is environmentally friendly and is less intrusive to communities when it is installed. Instead of ripping up roads, sidewalks and habitats, municipalities can choose to use a trenchless installation technique which results in less disruption to “Main Street” or the environment. PE pipe is joined together through a unique heat fusion process that creates a seal resulting in a strong leak-free system.
PE-HD pipe is much easier to handle and install than heavier, rigid metallic or concrete pipe, allowing for cost advantages in the construction process. It is structurally better able to withstand an impact than other pipe materials, especially in cold weather installations when other pipes like PVC are prone to cracks and breaks.
HDPE stands for high density polyethylene (many times just referred to as PE), and is made from ethylene, which can be derived from either crude oil or natural gas. PE Pipe is extremely strong, durable, flexible, corrosion free and chemical resistant.
In a nine-year span between 1995 and 2003 in Europe, PE pipes averaged around four failures per 100km per year, while ductile iron and PVC averaged around eight and nine failures per 100km per year, respectively.
PE is considered to be a re-roundable pipe and the cold ring clamps of a McElroy fusion machine may be used to re-roundlarger pipe. When desired, expandable stiffeners are available. They can be inserted into the pipe and then expanded with a triangular wedge. Romac makes these for pipes up to 12”. Cascade Waterworks sells these up to 20” DIPS. HDPE pipe does not undergo galvanic corrosion; therefore, it may be safely installed in hot soils that would attack metal pipes without any cathodic protection. PE-HD pipe is cost effective and has long term cost advantages due to its physical properties, leak free joints and reduced maintenance costs. Institute estimates the service life for PE-HD pipe to conservatively be 50-100 years.
HDPE pipe can be joined by thermal fusion to form a joint that is as strong as the pipe itself and is leak free. Thermal fusion eliminates potential leak points every 2-6 meters commonly found with Concrete, PVC and Ductile Iron pipe. Leak proof joints also eliminate infiltration and exfiltration problems experienced with other pipe joining methods. Since fused joints are self-restraining, costly thrust restraints or thrust blocks are not required
PE has exceptional capacity for handling recurring surge pressure. For instance, AWWA standards demonstrate that PE has resistance up to 150% of its pressure class under recurring surge pressure . Additionally, in a report on the cyclical fatigue strength of PVC and HDPE, Marshall and Brogden found that at a cyclical stress range of 10 Mpa (1450 psi), HDPE pipe reached 10,000,000 million cycles before failure.
HDPE requires trained technicians and special equipment. CLI's crews are certified and trained in the installation techniques Unlike other materials, PE pipe does not corrode over time and is not susceptible to chemical damage. It is also much more flexible and can move with different soil conditions and ground movement. Because it is light weight, it is easier to handle, transport, and fix, which in turn reduces costs.
Aside from the low cost of PE pipe, long term savings may be realized due to PE pipe’s fusion joints and corrosion resistance. Leakage rates for fused PE systems are far lower than for gasket jointed DI or PVC systems. PE pipe is resistant to corrosion. It will not undergo tuberculation and is unaffected by “hot” soils or electrogalvanic corrosion, thus PE pipes last longer in the ground. Additional savings may be realized by trenchless installation
Surge pressures in HDPE pipe are significantly lower than in DI pipe and lower than PVC pipe due to the lower value of dynamic modulus for HDPE. For example, in a typical 8” line a velocity change of 5 fps would cause a 51 psi surge in HDPE DR17 pipe, a 87 psi surge in PVC DR18 pipe, and a 262 psi surge in DI Class 350 lined pipe. Lower surge pressures often mean longer life for pumps and valves in an HDPE pipeline, as well as lower pressure class pipes.
PE-HD pipe can be bent to a radius 25 times the nominal pipe diameter. This can eliminate many fittings required for directional changes compared to piping systems made from other materials. In addition, the flexibility of PE-HD pipe makes it well suited for dynamic soils and areas prone to earthquake. PE-HD pipe for pressure applications can accept repetitive pressure surges that exceed the static pressure rating of the pipe.
Flexibility and leak free joints allow for unique and cost effective methods of installation of PE-HD pipe that the rigid Concrete, PVC and Ductile Iron pipes can’t use. These alternate installation methods (Horizontal Directional Drilling, Pipe Bursting, Sliplining, Plow and Plant, Submerged or Floating Pipe) can save considerable time and money in most applications
Yes. Up! According to Global Industry Analysts, Inc. the compounded annual growth rate (CAGR) for PE pipe is an astounding 6.13 percent through 2010, while PVC is falling behind with only a 3.84 percent growth rate HDPE can be obtained with National Sanitation Foundation (NSF) certification for suitability for contact with potable per NSF-61 Standard." Be sure to check availability before specifying HDPE in this application PE is considered to be a re-roundable pipe and the cold ring clamps of a McElroy fusion machine may be used to re-roundlarger pipe. When desired, expandable stiffeners are available. They can be inserted into the pipe and then expanded with a triangular wedge. Romac makes these for pipes up to 12”. Cascade Waterworks sells these up to 20” DIPS PE-HD pipe will not corrode, tuberculate or support biological growth. It is the material of choice in harsh chemical environments. PE-HD pipe has a smooth ID and maintains its flow capability over time - Hazen Williams C Factor remains 150, even after years of use.
Bottles, jars and other containers made of PET can be collected and recycled into a wealth of products. PET can be recycled into new PET bottles and containers, carpet and clothing, industrial strapping, rope, upholstery fabrics, boat sails, automotive parts, fiberfill for winter jackets and sleeping bags, construction materials, and many other items.
No. PET does not contain dioxins, nor can it produce dioxins, and no dioxins are created in the manufacturing of PET. Dioxins are a group of compounds sometimes formed by high-temperature combustion (over 750 degrees F.) and certain types of industrial processes involving chlorine. Dioxins can't be created without the presence of chlorine, and PET does not contain chlorine. Consequently, dioxins can't be produced when a PET container is heated or microwaved, exposed to sunlight, or washed and reused (all urban myths).
PE pipe transports potable water, wastewater, chemicals, and compressed gases.
Underground water pipes are a major long term (50-100 years) investment. In addition to comparing the initial purchase price, the long term maintenance costs and overall life-cycle costs should be carefully evaluated. According to the Federal Highway Administration, utilities spend $36 billion annually on corrosion protection of pipes. Because PE pipe does not corrode and does not leak at the joints, constant repair of aging metal pipes or leaking at the joints with all other pipes is no longer an issue. Initial cost savings are also realized with the opportunity for a trenchless installation. Compared to PVC and ductile iron, PE has the lowest life-cycle costs due to lower installation costs, lower repair rates, less water loss and lower energy costs.
If the ditch can be dewatered and the pipe dried off, fusion repair may be used. Otherwise, a mechanical repair is recommended.
Other types of plastic and iron pipes require joints to turn and link the pipe. These joints tend to lose water as it flows through the pipe. PE pipe is fused together so that the links are equally strong or stronger than the rest of the pipe, meaning that it holds water much better than other types of pipe
PVC pipe has a crystalline temperature of 32 degrees F, at which point it becomes as brittle as glass. HDPE pipe has a crystalline temperature of - 180 degrees F, which translates into less potential for failure. In fact, water can freeze & thaw repeatedly inside of HDPE pipe, without causing permanent damage to the pipe. HDPE is more durable and forgiving in most applications than PVC. By using proper fusion methods, HDPE does not have joints that fail like PVC. Polyethylene pipe is more flexible, and has greater impact resistance than PVC. HDPE can handle a scratch as deep as 10% of the wall thickness, without reducing the pressure rating of the pipe. PVC is notch sensitive, meaning PVC pipe has a higher inclination to fracture because of a notch, crack, or scratch. HDPE piping systems are also more surge tolerant than PVC, which means less repairs caused from pressure surges.
If a polyethylene piping system is in need of repair, electrofusion couplings are one of the simplest ways to facilitate repairs. Clamp-around repair couplings, like those available from JCM Industries, offer a traditional method of pipe repair. Depending on the size, polyethylene pipe has pressure ratings up to 267 psi @ 73.4 degrees F, with a 2:1 safety factor built in. Yes. You have to protect the joint during cold weather fusion from wind, moisture, and blowing snow so that the heater plate uniformly heats the end of the pipes Generally speaking, many saddle manufacturers have saddles/sleeves specifically made for use with HDPE pipe, and they are typically the same as those used with PVC pipe and sometimes the same as those used with ductile iron pipe. Service saddles often include double straps or extra wide straps and Belleville (spring) washers for use with HDPE pipe so that the tension on the strap remains constant once the nuts are properly torqued. As for tapping sleeves, some manufacturers such as JCM indicate that as long as it is a full sleeve in accordance with AWWA C110/111, it can be used on HDPE pipe. Check with the manufacturer for specific information. No. PE pipe is known for its flexibility, toughness and chemical resistance. PE pipe can withstand great pressure changes due to its outstanding ductility and toughness. These performance characteristics make PE pipe an excellent choice for dynamic soils and earthquake prone areas that require a strong, long-lasting and corrosion-resistant pipe that is also flexible enough to be installed and assembled in harsh and challenging environments. |