Operators of sewer systems using non-pressure polyethylene and polypropylene pipes can expect the polyolefin products to have a service life of at least 100 years, according to a technical report published by the European Plastic Pipes and Fittings Association (TEPPFA).
The findings are based on a two-year study of pipes excavated from five sites in Finland, Norway, Denmark and Germany. One pipe made of first-generation high density PE had been in the ground 38 years and the PP pipes had been in operation 10-23 years.
The tests found no excessive deterioration or degradation and the results demonstrate the long-term performance of solid wall and structured wall sewer pipes using long-term, real-time data, according to TEPPFA.
The study comes on the heels of a 2014 U.S. study about PVC pipe longevity by the Utah State University, which found PVC pipes that are properly produced and installed should last more than 100 years.
In Europe, polyolefin pipe systems have been widely used for more than 40 years but no scientific study on service life expectancy had been done on pipes that operate with a constant strain in sewage and drainage applications but without internal pressure, TEPPFA says.
Heinz Dragaun, a professor at Technologisches Gewerbe Museum (TGM), a technical education school in Vienna, Austria, independently validated the study commissioned by TEPPFA.
The results should be relevant to material suppliers, pipe manufacturers and contractors working in the sewer market, according to TEPPFA General manager Tony Calton.
“Designers, owners and operators of sewer networks can now be confident that these sewer systems will have an in-service life of at least 100 years when materials, products and installation practices meet the the appropriate requirements,” Calton said in a news release.
“Clearly it will lend further appeal and allow polyolefin sewer pipes to be specified with increased confidence as they perform consistently throughout their very long asset life.”
The TEPPFA results, which were made public earlier this year, have resonated in North America, too, according to Tony Radoszewski, president of the Plastics Pipe Institute, which is based in Dallas and has about 140 members that are mostly manufacturers.
In the last 20-30 years, HDPE corrugated pipe has made “significant inroads” as an alternative to reinforced concrete pipe in storm water pipe systems and HDPE solid wall pressure pipe has been competing against ductile iron for sanitary sewer force mains, Radoszewski said in an email.
“While the use of PE and PP pipe for sanitary sewer applications is relatively new in North America this does provide end users with increased confidence that the advanced generation PE and PP materials used to make contemporary pipes will provide an expected lifetime of at least 100 years when properly manufactured to existing standards and installed using best practices and standards,” he said. “For the municipality, this is good news as it now offers more alternatives to consider when designing their sewer systems.”
The TEPPFA study reflects the current state of many municipalities that operate combined sewer systems, which manage both rainwater and sanitary sewage, Radoszewski said. Combined sewers can cause serious water pollution problems when a heavy rainfall exceeds a sewage treatment plant's capacity and leads to an overflow of untreated sewage into streams, rivers and lakes. This type of sewer design is no longer used in the construction of new U.S. communities and older cities have to either upgrade their system by separating the flows of rainwater and sanitary sewage or face federal fines.
The TEPPFA and Utah studies show plastic pipes are a viable alternative to legacy pipe materials like concrete and iron, Radoszewski said.
“When one considers the actual service life of these pipes, properties such as corrosion, chemical and abrasion resistance demonstrate the superiority of plastics,” he added. “Equally as important is the value proposition plastic pipes bring to the municipalities. Typically, plastic pipes are more competitively priced and easier to install due to their lighter weight advantage. So yes, this is good news for the plastic pipe industry in North America.”