Non-Pressure Pipes

non-pressure

Non-pressure pipes include tubes, corrugated pipe, structured wall pipe, and ducting.

Typical requirements
Non-pressure pipes must primarily offer long life, strength, and resistance to corrosion and abrasion, as well as low installation costs. Plastic pipes meet these requirements. Not only do they offer low installation costs, but the smooth inner walls assure high-gravity flow rates and minimize the chances of developing stoppages.

A key example is plastic sewer pipes, which have adequate strength for earth loads and high chemical resistance — meaning long life when used for sewer installations. Plastic pipes are also easily coiled, and therefore more cost-effective to transport — vital in a market where keeping costs down is so important.

Lifetime: up to 50 years
Pressure: non- and low-pressure applications
Temperature: 0-40°C

Environment
Pipelines made from polyolefins may be designed to last for 50 years or more, allowing an inert, low-maintenance system to transport vital liquids in a leak- and corrosion-free environment. The thermoplastic nature of polyethylene and polypropylene resins allows clean pipes to be recycled and used in other non-pressure pipe applications.

Applications and relevant Dow resins
Non-pressure pipes are primarily used for sewage, drainage, storm drains, and telecom applications. Because it is primarily laid beneath the ground surface, the conduit must possess outstanding strength and durability and be resistant to aggressive soils and chemicals. It must also have good abrasion resistance.

A key parameter in this application area is ring stiffness and the ability to withstand top loads without buckling, which requires a resin with good tensile modulus properties. The design of the pipe wall is particularly important, with corrugated or structured profiles imparting additional strength to the pipeline while maintaining a light weight.

Pipes manufacturers are increasingly turning to polypropylene resins in the non-pressure pipe sector, as they combine low density with high melt strength at competitive prices. INSPIRE* Performance Polymers offer good processability, low-temperature impact resistance, high stiffness and strength, and good service temperature. Manufacturers can achieve output rate increases of up to 40%, as well as a combination of outstanding performance properties combined with excellent low-temperature impact resistance. Typical applications for INSPIRE Performance Polymers include corrugated pipes for sewage and drainage, and cable conduits.

Plastic is also increasingly being used for lining pipes — the precise material used being highly dependent on the performance needs, which vary between pressure, chemical, and temperature resistance. For example, pipes are lined during repair to increase resistance to chemicals or corrosion or to improve water quality. In addition, although a technically demanding application, replacing traditional liners such as duplex steel with PE-lined carbon steel can result in significant savings.


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