Large diameter HDPE pipe for municipal piping system

For many years, the large diameter (16 inches and above) water pipe market has been represented by Steel Pipe (SP), Precast Concrete Cylindrical Pipe (PCCP), Ductile Iron Pipe (DIP) and PVC (Polyvinyl Chloride) pipe. On the other hand, HDPE pipe only accounts for 2% to 5% of the large diameter water pipe market.

This article aims to summarize cognitive issues associated with large diameter HDPE pipes and recommendations for pipe connections, fittings, sizing, design, installation, and maintenance.

According to the EPA report, the cognitive issues surrounding large diameter HDPE pipes boil down to three main points. First, there is a general lack of understanding of the product. In municipal projects, the number of stakeholders can complicate knowledge transfer for related products. Likewise, workers typically use familiar products and technologies. Finally, this lack of knowledge can even lead to the misconception that HDPE is not suitable for water applications.

A second cognitive problem stems from the notion that using new materials increases risk, even when some knowledge is available. Users often see HDPE as a new product for their specific application, out of their comfort zone because they have no experience with it. A major driver is needed to convince utilities to try new materials and applications. It's also quite interesting.

The best way to overcome these perceived problems is to help quantify the perceived risks and demonstrate the quantifiable benefits of using new materials. Also, it can be helpful to look at the history of similar products in use. For example, natural gas utilities have been using polyethylene pipes since the mid-1960s.

While it is relatively easy to talk about the physical and chemical properties of HDPE piping, a better way to help quantify its benefits is to describe its properties in relation to other piping materials. In a survey of 17 U.K. utilities, researchers outlined the average failure rate for various pipe materials. Average failure rates per 62 miles ranged from 20.1 failures on the high end of the iron pipe to 3.16 failures on the low end of the PE pipe. Another interesting finding of the report is that some of the PE used in the pipes was made more than 50 years ago.

Today, PE manufacturers can create reinforced polymer structures to improve slow crack growth resistance, tensile strength, ductility, allowable hydrostatic stress, and other pipe material properties. The importance of these improvements cannot be overstated. During the 1980s and 2000s, a survey of utility companies' satisfaction with PE pipes changed dramatically. Customer satisfaction hovered around 53% in the 1980s, rising to 95% in the 2000s.

The main reasons for choosing HDPE pipe material for large diameter transmission mains include flexibility, fusible joints, corrosion resistance, compatibility with trenchless technical methods such as horizontal directional drilling, and cost savings. Ultimately, these benefits can only be realized when proper construction methods, especially fusion welding, are followed.



Post time: Jul-31-2022