Chapter 1: HDPE History and Background

High-density polyethylene (HDPE) popularity and usage continues to increase. Plastic, particularly HDPE, is part of our everyday lives, from household products to industrial applications. Since its creation almost 70 years ago, HDPE piping and conduit has become a preferred material in the power, communications, and energy industries. HDPE conduit is a flexible and versatile product well-suited for numerous industrial settings. Specific applications include conduit for telecommunications and fiberoptic lines; flowlines for oil and gas; gas transmission and cross-country pipelines; and municipal water and sewer lines.

HDPE was discovered by scientists at Phillips Petroleum in 1951. Polyethylene, a low-density thermoplastic with a variable crystalline structure, was invented in the 1930s by Imperial Chemical Industries. High pressures – 20,000 to 30,000 pounds per square inch (psi) – are required to produce polyethylene. Phillips scientists J. Paul Hogan and Robert Banks developed a process using nickel oxide and chromium oxide catalysts that produced a new ethylene polymer at much lower pressures than required for traditional polyethylene. The new material, HDPE, was harder, stronger, more durable and more heat-resistant than any existing plastic material. The methods they developed are still used to produce HDPE today.

HDPE is a high-density plastic that is strong yet flexible. HDPE has a linear molecular structure, unlike low-density polyethylene (LDPE), which has a branched molecular structure. The linear molecular structure of HDPE allows its polymer chains to pack closely together, creating a dense and strong material. While LDPE is cheaper to produce and more flexible, HDPE’s strength and durability make it an ideal product for many industrial and household applications. HDPE materials like pipe are manufactured from resin.

HDPE is much stronger and lighter in weight than conventional pipe, yet more flexible than materials like concrete and iron. HDPE heat-fused joints are as strong as or stronger than metal pipe and do not leak. HDPE pipe offers unmatched corrosion and chemical resistance as it will not corrode (rust), tuberculate or support biological growth. HDPE pipe is expected to have a service life of 50 to 100 years and is fully recyclable.

HDPE and Plastics Organizations

Three organizations have had significant influence on the adoption and usage of HDPE piping: The Plastics Pipe Institute (PPI), the American Society for Testing and Materials (ASTM) and the American Water Works Association (AWWA).

Founded in 1950, PPI is the major trade association representing all segments of the plastics piping industry. The PPI mission is to advance the acceptance and use of plastic pipe systems through research, education, technical expertise and advocacy. The PPI’s publications index page contains comprehensive reports related to specific areas of design, operation and manufacturing. It is intended to assist engineers, code officials, specifying groups and users with information on implementation of plastic pipe.

ASTM, organized in 1898, is a nonprofit standards-developing organization covering global industries in 140 participating countries. Volunteer members serving on standards-writing committees develop technical documents for numerous industry sectors including plastics. ASTM’s plastics committee has over 500 members. The standards developed by the ASTM are intended to ensure quality and safe use of plastic material, including pipe.

AWWA is an international nonprofit scientific and educational society founded in 1881. It is dedicated to providing total water solutions that ensure effective water management. AWWA provides HDPE-related manuals and standards that assist engineers with design, specification, procurement and installation procedures of HDPE pipe and fittings.