U.S. Develops New Technology and New Products for Polyethylene Plastic Pipes

In order to meet the evolving needs of urban gas distribution systems, the GTI development laboratory has recently launched a series of new technologies and new products related to "high-tech" polyethylene (PE) plastic pipes, including:
(1) Magnetic PE pipes that are easy to detect on the ground;
(2) High-strength plastic pipe suitable for working under high pressure - polyamide 11 (PA11);
(3) Cross-linked polyethylene (PEX) tubes that can operate at high pressures as well as at high temperatures.
In recent years, GTI is working hard to solve two problems in the gas industry: one is the need to directly locate buried pipelines; the other is to replace high-pressure steel pipes with low-cost, easy-to-install plastic pipes.
At present, more than 90% of gas distribution pipelines in the United States are installed with PE pipes. With the continuation of the research on PE pipe positioning technology and the development of a commercial positioning tool, GTI is now conducting a complementary study with a view to developing a magnetic PE pipe that can be located on the ground to be used as a substitute for ordinary PE pipe. . So far, researchers have successfully demonstrated the feasibility of manufacturing magnetic PE tube materials, which makes it possible to position the gas distribution system in the future and become an easy way to install. The 4 in diameter magnetic PE tube test has been completed and studies have shown that this material can be positioned 5 ft deep underground. Normally, to help the positioning of ordinary plastic pipes, it is necessary to install metal traces in the pipes, and an average installation cost of 5 to 10 cents per line of pipe is increased. Magnetic PE tubes do not require metal traces, allowing long-term accurate positioning and easier installation.
Another new plastic pipe material - PA11, in addition to the advantages of PE pipe, increases the operating pressure of the pipeline (up to 200psig) and the temperature range of application, operating pressure is equivalent to 2 times the same size PE pipe, and Meets ASTM standards.
GTI is studying PEX materials for the needs of pipeline installation under special conditions. By cross-linking treatment, the structure of the polyethylene is changed, the pipeline strength is higher, the operating pressure is above 100 psig, and the temperature reaches 90°C. Studies have shown that PEX materials also have better wear resistance and can be used in pipelines installed in rocky soils, trenchless installations, high ground temperatures, and PE bridges where the use of PE materials is prohibited. At present, PEX materials are being used in gas distribution pipelines in Europe. However, the United States restricts its use in water pipelines. Due to the increased operational performance of PEX materials, the United States may use it as a candidate plastic material for next-generation gas pipeline systems and is fully studying its performance to ensure that low-cost alternatives to steel pipe lines are achieved. GTI and Public Service Electric have started a research project to determine the range of operating parameters for PEX pipes. Several PEX pipes with a degree of crosslinking of 60% to 90% are tested under various field pressures, temperatures, and soil conditions. Includes on-site operation techniques, such as extrusion and connection technology tests. Laboratory data will be used to predict the long-term use of field performance and reliability of the life of the distribution pipeline.
By combining the effects of industrial testing and development, future gas distribution systems will be safer, lower installation costs, and easier to maintain. The key to the application of high-tech plastics will be to continuously improve the performance of materials.