Pipe group encourages innovation

PVC resin production ramped up in the early 1950s to meet demand from a rapidly growing country, including new applications for potable water and sewer pipes that were lightweight, could resist chemicals and didn't rust like traditional iron pipes.

Polyethylene pipes were introduced a few years later with other benefits attractive to cities and utilities, and an emerging industry began to establish its foundation. However, challenges that face many new products also began to surface.

“People were wondering how long will this stuff last, what pressures can it handle and for what length of time,” Tony Radoszewski, president of the Plastics Pipe Industry, said in a telephone interview. “There was a need to establish confidence in the long-term performance of plastic pipes.”

The Dallas-based trade association responded in 1958 with the formation of a nine-member evaluation committee now called the Hydrostatic Stress Board (HSB).

“They started to address concerns so this emerging industry could get the confidence of design engineers so they'd start using the products,” Radoszewski said.

Almost 60 years later, HSB is still at it with up to 25 engineers, chemists, scientists and other experts in thermoplastics serving as volunteers. They provide guidance to the industry on demonstrating the long-term strength of the material produced by resin manufacturers, the composite structures produced by pipe manufacturers, and the ingredients used for final compounds.

Applicants seeking an HSB listing have a role in products aimed at gas, municipal water, wastewater, sewer and industrial water systems. With the evolution of plastics and pipe structures that have multiple layers of multiple materials, the board's work has become more complex and dynamic in recent years. This is spurring some changes at PPI, which has reconstructed the HSB website to expedite the listing process.

To keep its pipeline moving, HSB added downloadable forms and templates to submit requests for ingredients, resins, compounds and composite plastic pipes. The website also now has policy reports, step-by-step instructions and an “announcements” page to keep everyone up to date about board activities and developments.

“It's almost nostalgic to think of the early days when there was only PVC and PE in pipe,” Radoszewski said, adding that the HSB now has multiple committees focused on specific aspects of complex pipe advancements.

“For example, the polyolefins committee is developing policies on PP-R, PP-RCT, PE-RT, PA and PVDF. The vinyl committee is responding to industry requests to allow manufacturers to qualify a range of heat stabilizers allowing more flexibility for pipe producers. The composite committee is expanding its policies from polymer/metal/polymer structures to include multi-layer polymeric pipe.”

Although the PPI board of directors has oversight, HSB has its own code of ethics and standards of operation when it comes to policy development and authorization of listings in the HSB program. The group is chaired by PPI's technical director, Sarah Patterson.

“HSB policies define procedures for determining the long-term hydrostatic strength of plastic pipe compounds and for converting this strength into an allowable design stress, which, in turn, is used to determine the pressure rating of the plastic or composite pipe,” Patterson said in a news release.

Their work focuses on several methodologies called hydrostatic design basis, pressure design basis, minimum- and categorized-required strength, and strength design basis. In addition to significant time, the HSB members have to be willing to represent the industry as a whole.

“The HSB allows for checks and balances,” Radoszewski said. “You have all these people knowledgeable about different aspects of the thermoplastic industry working together for the benefit of the entire industry. The beauty of this is there's a kind of honest brokerage that occurs.”

The HSB program is cited in product standards developed by organizations, such as ASTM International, American Water Works Association and the CSA Group (previously the Canadian Standards Association) as well as code bodies like the American Society of Mechanical Engineers, according to Patterson.

A listing in the HSB program doesn't require PPI membership. The program is offered as a service to the entire plastics industry. Radosczewski said this is important for two reasons.

“Firstly, this shows integrity and a commitment by people in the plastics industry to make sure their products are understood and used properly,” he said. “Secondly, we are all users of plastic pipe for drinking water, sanitary sewers and gas distribution. We all want to make sure those systems operate safely today and for our kids and grandkids. As a testament to this effort, the PPI HSB is recognized in numerous codes and standards in nearly all pressure pipe applications.”

Radoszewski likens HSB to “a touchstone in turbulent waters.”

“At the end of the day, what we're trying to do is build on a foundation going back to the 1950s to address the needs of design engineers and those creating new materials so there is one place to get clarity in what is becoming a very complex industry,” he said.