Polyethylene (PE), a thermoplastic base material, was first produced in 1933. Over the next 20 years, petrochemical industry chemists advanced the manufacturing process to reduce costs while producing better value. In the early 1950s, chemists at Phillips Petroleum Co. develop economic processes and produce a new class of polyethylene called high density polyethylene (HDPE). At that time, it became possible to make various levels of PE, and soon the basic ingredients were used in various products and applications.
The first use of HDPE is for baby bottles. Using it instead of glass was the beginning of HDPE replacing traditional materials because of its improved physical properties. It does not break like glass, is cheaper to produce, and safe. At present, HDPE has replaced glass for bottles and metals for buckets, drums and gas tanks, and is used for many other applications, including packaging and piping components and systems. According to the December 2016 Plastics News report, HDPE sales in North America and Mexico have reached nearly 16 billion lb, with more capacity starting to operate the following year.
The History of HDPE pipes
For pipes, the HDPE class used now is different from the initial generation materials, and even very different from other HDPE materials used in consumer applications today. HDPE-grade pipes are highly engineered compounds designed for long-term service in critical applications. It was put through a series of rigorous testing procedures before it was available for manufacturing.
Solid wall HDPE pipes began to replace metal pipes in oil and gas collection systems in the late 1950s. In the early 1960s, gas utilities began replacing failed iron pipes with PE pipes, and because of their successful performance history, 95% of all new gas distribution systems currently installed use PE pipes. Soon, corrugated HDPE pipes began to replace clay pipes in agricultural drainage systems. In the late 1980s, large diameter corrugated HDPE pipes began to replace metal and concrete in storm culverts. The material continues to develop into what is now the third and fourth generation of development, each with enhanced performance capabilities.
The thermoplastic piping system is sustainable and environmentally responsible for pipeline selection.
They are energy efficient during manufacture and provide peak protection from contamination during service. They also require far less energy to make, transport, and install than metal or concrete. With corrosion and abrasion resistance, plastic piping systems also provide long life, provide excellent connection performance and offer leak-free protection, making it a good value.
For centuries, farmers knew that proper field drainage, along with irrigation, was an important part of increasing crop yields, so they used clay tiles. Studies show that soybean yields increase by 43% and corn by 30% when fields are “milled”. With the advent of HDPE resin and the ability to make corrugated pipes, the agricultural market is the starting point for the development of more pipes. In less than a generation, corrugated HDPE pipes move products that have been used for hundreds of years. Larger diameters are soon followed to provide new applications, especially in the transportation department and other public storm drainage projects.
Polymers for Performance
Pipeline HDPE resins are compounds consisting of PE copolymers, also known as resins, which are added to coloring agents, stabilizers, antioxidants, and other ingredients to improve the properties of these materials. The formulation produces HDPE pipes, which are tough, durable and strong.
HDPE pipe materials are almost exclusively classified as thermoplastics because they soften and melt when sufficiently hot and then harden when cooled. This process can also be reversed, allowing resins to be recycled into other applications at the end of pipe life.
As a material that is widely tested, HDPE pipes provide performance that has been widely documented and validated continuously through ongoing laboratory research and decades of service in the field. Design engineers for other utilities continue to find benefits and identify new uses for HDPE products. For example, because PE produced for pipes is engineered resin, it provides pipes with a favorable strength-to-weight ratio. Some reasons for the wide and varied application of HDPE pipes include ease of material handling and freedom from attack by soil, chemicals, ambient water and moisture, and the fact that it will not corrode or rust. Because HDPE is a non-electrical conductor, it is immune to electrochemical-based corrosion processes caused by electrolytes such as salts, acids and bases.
HDPE pipes are not susceptible to biological attack or tuberculation, are resistant to biological blockages, and maintain a high and consistent flow capacity throughout the life of each system. This reduces wear, providing significant savings for operating utilities.
In addition, miles and miles of corrugated HDPE pipe can be quickly installed because the diameter is smaller than 6 in. Can be purchased in large rolls of thousands of feet of pipe, especially for tile farming.
Code for Compliance
Beyond the standards for materials formulated to make corrugated HDPE pipes, it is important to note that the pipes are produced, certified and installed in accordance with various industry standards from organizations such as AASHTO, ASTM, CSA Group and American Railway Engineering and Maintenance-of-Way Assn. (AREMA). Plus, it is approved for use by the Federal Aviation Administration, the transportation department, and other federal and local agencies. This national standard is routinely reviewed by various industry organizations and their membership. Efforts are continuing to maintain current standards, improve and strengthen testing criteria, and advance for raw materials and post-production pipelines. Testing protocols can be extensive and extreme.
For example, one test for the railroad industry was carried out by the Transport Technology Center Inc. at the Facility for Acceleration Testing Services in Pueblo, Colorado, where he operates a test bed for the railroad track. The methodology for this test includes repeatedly running a train consisting of four locomotives and 80 carriages weighing 315,000 lb more than 48-in. corrugated HDPE pipe with a 4 foot cover between the top of the pipe and the bottom of the rail. In addition to performance evaluations, the long-term impact of static and heavy loads on the pipe is assessed by parking the car, with a set of wheels on the track directly on the same pipe for six weeks. After this test and after reviewing the accumulated data, the use of an approved HDPE pipe was added to the AREMA manual.
By sending products and passing independent tests, manufacturers ensure customers that their products meet standard requirements, including requirements on physical property, joining and installation methods.
Confidance of Pipes Coupling or Jointing Connection
Initially, the only connecting mechanism for corrugated HDPE pipes was to connect a screw that secures two plain-end pipes to form a waterproof connection. This type of coupler is still commonly used in agricultural applications, when making connection fittings in the field, and in other applications. Connections with higher integrity between pipe sections were developed during the 1980s with bell-joint systems, usually used more for sanitary sewers than rainwater drainage systems. Then the integral bell and tap type clutch are perfected. This remains the most commonly used union method for double wall corrugated HDPE pipes. The next generation of screws has an extended inner sheath that provides more binding for the pipe parts. This can help in situations where watertight integrity is required and where field verification tests are carried out at the connection.
While today, corrugated thermoplastic pipes are available in sizes up to 60-in. diameter, there are projects being carried out by machine manufacturers to make pipes in 72 and 84-in. diameter. One of the latest developments in the US is the availability of polypropylene pipes in diameters up to 60 in. With a structural core that provides higher beam stiffness and strength. Engineered levels of polypropylene are resistant to chemicals – even sulfuric acid found in sanitary sewers.
The practicality of HDPE systems and polypropylene pipes has been recognized. These materials are now used in larger volumes for drainage and drainage projects. Resin availability is increasing, pipe manufacturers are increasing production capacity, and new developments in raw material and pipeline system design illustrate that the application of thermoplastic pipes is a smart and reliable choice. The industry will continue to be involved in progress – as the industry has done for more than half a century. As a comprehensive and progressive solution, the thermoplastic pipe system will provide services and meet the demands of the world for generations to come.
source article : Evolution of HDPE
source articles written by : Daniel Currence – P.E.
source articles website : https://www.ads-pipe.com/news-media/evolution-hdpe
editor and uploader : Andreas Mikio – PT. Shuanglin Pipe Indonesia
English
Chinese (Simplified)
Indonesian
Japanese
