Ningbo Fangli Technology Co., Ltd. is a mechanical equipment manufacturer with nearly 30 years’ experiences of plastic pipe extrusion equipment, new environmental protection and new materials equipment. Since its establishment Fangli has been developed based on user’s demands. Through continuous improvement, independent R&D on the core technology and digestion & absorption of advanced technology and other means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE water supply / gas pipe extrusion line, which was recommended by the Chinese Ministry of Construction to replace imported products. We have gained the title of “First-class Brand in Zhejiang Province”.
Polyethylene (PE) pipe was first commercially made in the 1940s, after World War II. Today, it is the second most widely used plastic pipe material, after polyvinyl chloride (PVC). These two materials account for over 90 percent of all currently produced plastic pipe.
PE is a non-conductor and therefore not susceptible to galvanic or electrochemical corrosion —the mechanism that limits the durability of buried metallic pipes. It is also unaffected by most acids, alkalis, and corrosive salts.
Its excellent toughness and flexibility distinguish PE. It is very resistant to damage by impact, even at lower temperatures. It is a ductile material that does not shatter even if punctured or cut regardless of service temperature. It withstands the effects of cyclic or repeated stressing (such as by water pressure surging). Its greater flexibility permits the coiling of smaller diameter pipes, which reduces fitting requirements and facilitates installation. PE pipe’s toughness allows it to resist failure under the expansive action of freezing water.
To protect PE pipe during extended outdoor storage against the effects of the sun’s ultraviolet (UV) radiation — which over time can damage most plastics – PE pipe compositions include additives that either physically screen or chemically absorb UV rays. The commonly used UV screen is finely divided carbon black, hence the black color of many PE pipes. Black PE pipe has excellent weathering resistance. Pipe made to other colors relies on stabilizers to absorb UV rays.
Of course, once installed underground or away from sunlight, UV protection is no longer needed.
While PE pipe has sufficient strength, toughness, and chemical resistance for water service pressure piping in common with other plastics, it has certain limitations on its performance just as any other engineering material. These limitations include the following, which must be recognized and addressed to ensure a proper and durable installation:
• Mechanical properties are temperature sensitive. As temperature increases, PE becomes less strong and less stiff. For continuous use where the pipe temperature exceeds 80°F, the pipe pressure rating should be appropriately reduced.
• The coefficient of thermal expansion/contraction is higher than metal. For the same change in temperature, unconstrained PE pipe expands about 8 times as much as metallic pipe. Installation must prevent the development of excessive pipe contraction forces which, while normally not damaging to the pipe, can produce higher than desirable pull-out and bending loadings at the point the pipe connects with a rigidly held fitting.
• Shear strength is relatively low. Installation must avoid the development of high shear stressing, which can occur in a flexible pipe subject to overburden from above while connected to a fixed, immovable structure, such as a service tap on a water main.
• Kinking can compromise mechanical properties. Pipe should not be bent so tightly that it kinks either during handling or while in service.
• Mechanical properties can also be compromised by gouging, cutting, and excessive abrasion. PE pipe should be handled and installed to prevent the possibility of excessive damage.
• Certain solvents can permeate the pipe wall. Plastic water service pipe, like most piping materials in general, should not be installed in soils which are contaminated, or can be subject to contamination, by organic solvents.
Chlorine used as a disinfectant must not exceed the requirements of ANSI/AWWA C 651, Standard for Disinfecting Water Mains. For potable water systems using chlorine as a disinfectant, the recommendation limits chlorine dosage to 25mg/l free chlorine with a residual of 10 mg/l at the end of a 24-hour stand. Daily amounts of chlorine should not exceed 3 ppm at temperatures in excess of 75°F.
Additional Information. PE piping is widely used for many other applications, including municipal water distribution systems; drop piping for submersible pumps; ground coupled heating/cooling systems; gas distribution; oil and gas production; gathering gas generated by land-fills; conveying corrosive fluids; conveying slurries, sewerage, and drainage; and pipeline rehabilitation.