PIPE STIFFNESS AND DEFLECTION TESTING OF COILABLE HDPE CONDUIT AS RELATED TO BURIAL DEPTH
|Publication Date:||1 December 2019|
High-density polyethylene (HDPE) conduit is the preferred material to house and protect electrical power and telecommunications cables within. It offers unmatched corrosion and chemical resistance, is flexible and durable, and is available in long reel lengths to reduce joints and installation time. HDPE conduit is available in a variety of sizes, colors, dimensions and lengths.
Continuous length coilable HDPE conduit has enjoyed tremendous growth, not only as a protection for electrical cable, but largely due to the huge expansion of the communications industry in North America and abroad to protect fiber optic cable. HDPE's availability in long lengths, combined with its ductility, strength, and durability make it ideally suited for trenchless installation technologies such as horizontal directional drilling (HDD). Buried cables installed within HDPE conduit are protected from damage caused by storms, wildlife, vegetation, vehicles, and vandalism, when compared to aerial cables. Conduit also extends the life and reliability of underground cables by providing added protection against ground movement or unstable soil. These permanent raceways also allow for easier and less costly future cable replacements.
HDPE conduit has been used for decades with great success due also to its low coefficient of friction, resistance to corrosion, excellent chemical resistance, and ability to remain ductile (flexible), even at low temperatures. HDPE conduit can be provided on coils or on steel reels in long lengths, ideal for trenchless or plowing installation technologies. For example, a reel of nominal size 1 ¼ HDPE conduit can contain as much as 8,500 feet (2,590 m). Larger diameter HDPE conduit (e.g. nominal size 8 or greater) is available in straight lengths, also known as "sticks", up to 50 feet (15.2 m) long.
Polyvinyl chloride (PVC) is an alternative plastic material used for conduit. It is a more rigid material with lower flexibility, and is not coilable. PVC is normally supplied in straight lengths limited to 10 feet (3.04 m) or 20 feet (6.1 m), with individual pieces joined using solvent cement.
This Technical Report will provide information about industry terms related to pipe stiffness and deflection, particularly of HDPE conduit, and describe technical differences between HDPE and PVC conduit, as related to these terms and other properties.