Home > Products and Applications > FAQs
Please contact Global Poly Systems directly for any further questions not covered in this section.
Q. What fittings are available for HDPE pipe?
A. Global offers a wide range of HDPE fittings in standard configurations. These can be fused directly to the HDPE pipe. Custom fittings are also available upon request.
Q. In what lengths is HDPE pipe available?
A. Global produces pipe to 5" in coils, reels and 2" to 24" in straight lengths to 60 ft (18M).
Q. Is the pipe available in both ductile iron pipe sizes, metric and iron pipe size outside diameters?
A. Yes HDPE pipe is available in iron pipe (IPS) and ductile iron pipe sizes (DIPS), Ductile iron pipe sizes are available in 3 inch to 20-inch diameters. Iron pipe sizes are available from 2 to 24 inch diameters. Metric sizes from 18 cm to 609 cm are also available.
Q. Is Global's HDPE certified for potable water use?
A. Yes. Global's HDPE piping used for potable water with the initials us NSFc. This means the product conforms to NSF Standards 14" Plastic piping components and Related Materials" and Standard 61 "Drinking Water Systems Components-Health Effects" and "CSA 137.1"
Q. What is the life expectancy of HDPE pipe?
A. Current accelerated testing methods indicate that HDPE pressure pipe will last longer than 50 years.
Q. Is polyethylene pipe affected by chemicals?
A. Plastics are not subject to galvanic corrosion, as are metals, since they are not conductors. However, plastics can be affected through attack, strain corrosion, or salvation. The extent of the resistance is a function of many items, including time, temperature, and stress of contact. For more information you can consult PPI Technical Report TR18(38), Thermoplastic Piping for the Transport of Chemicals.
Q. Is HDPE able to handle ozone?
A. Yes HDPE pipe has a limited resistance and consequently a limited service life when conveying ozone at up to 120 degrees Fahrenheit. Over time the pipe will become brittle. The phenomenon occurs faster for thin wall pipes, and slower for thick wall pipes.
Q. Will sunlight adversely affect HDPE pipe?
A. If the proper amount of ultraviolet stabilizer has
been added to the colored pipe resin, non-black pipe can last several years in
outdoor storage. Non-black pipe is not recommended for permanent outdoor use.
Q. Will HDPE pipe float in water?
A. Yes. HDPE pipe has a specific gravity of about 0.95 so it will float. For underwater, anchored pipeline installations, it is important to specify the proper weights and spacing of the weights. Screw-anchors are a practical alternative. Whenever possible, an underwater pipeline should be installed in a trench with protective crushed rock cover.
Q. What is the temperature range across which HDPE pipe may be used?
A. The upper limit for pressure service is 140 degrees F. The low temperature limit is usually regarded as minus 130 degrees F. Cold temperatures do not adversely affect HDPE in static applications.
Q. Will HDPE pipe wear less than other materials in a slurry application?
A. Yes. In general terms, with adequate particulate suspension, HDPE pipe has an extremely high resistance to abrasion from slurries. In some applications, HDPE pipe has outlasted steel pipe by as much as 4 to 1 for a given situation.
Q. Can HDPE pipe be used in permanent above ground installations?
A. Yes. In many mining and industrial applications, HDPE pipe has been installed above ground and has provided and continues to provide excellent service after 15 to 25 years, with the potential to remain in service for many more years.
Q. How are HDPE solid wall pipe and components joined and connected?
A. HDPE pipe is normally joined by heat fusion, Butt fusion, socket fusion, sidewall fusion and electro-fusion are all heat fusion methods that create a leak free joint stronger than the pipe itself. The but-fusion procedure is most frequently used joining procedure.
Q. Why is it necessary to consider the working pressure rating (WPR) of a plastic piping system, instead of just considering the pressure class (PC) of the pipe?
A. Actually, you should make this evaluation regardless of the pipe material being considered. Steady state pressure (no flow or constant velocity) within a pipe induces a stress in the pipe wall. The measure of a pipe's ability to be pressurized is its pressure class. However changes in flow velocities introduce additional stresses in the pipe wall. The physical characteristics of a pipe material plays a significant role in determining the magnitude and frequency of this induced surge or water hammer stress, Pipe made of stiffer materials experience much higher surge stress levels and more frequent stress changes, while often having a less ability to tolerate surge and fatigue stresses.
Q. Will HDPE pipe of the same OD size as DI pipe deliver the same flow?
A. The inside surface of HDPE is extremely smooth and has a very long-term design coefficient to use with Ductile Iron Pipe recognizes the likelihood that the ID roughness will degrade over time. The smooth bore of HDPE pipe is maintained throughout its service life, It is often possible to use a polyethylene pipe with a smaller inside diameter than the comparably sized iron pipe, and still achieve and equal or greater flow.
Q. Are bedding and backfill procedures different for HDPE pipe that for PVC pipe?
A. No, HDPE and PVC pipelines are installed using the same standard backfill procedures. Both are thermoplastic materials, requiring the same considerations for proper embedment and backfill. The popular ASTM standard D2321 applies to both pipes materials.
Q. What percentage of external surface scratching or scarring is permissible on HDPE pressure pipe?
A. Scratches or cuts to a maximum depth of 10% of the pipe pipe wall are acceptable. The depth of the cut or scratch is measured from the pipe's original OD surface to the valley of the indentation.
Q. To avoid kinking the pipe, what is the allowable bending radius of HDPE pipe?
A, The rule of thumb is to use a minimum bending radius of 50 times the nominal diameter of the pipe.
Q. Is expansion and contraction of HDPE pipe a problem?
A. No. All objects expand and contract, As with all materials, expansion and contraction must be taken into consideration when designing a HDPE piping system, The resistance to movement provided by friction between the pipe and its embedment is usually sufficient to prevent thermal expansion and contraction,
Q. Are there recommended SDR's for directional drilling?
A.HDPE used in directional drilling must be designed to resist internal pressure, external loadings and pull back forces. Therefore there is no standard guideline for choosing an SDR. Please consult PPI Handbook's chapter on HDD.
Q. Is HDPE pipe suitable for use under railroads?
A. Yes, HDPE pipe is suitable for direct burial under railroads with just 4-5 feet of cover. An engineering burial analysis is recommended.