< PLUMBING
PLASTIC PIPE SIZING HPAC Magazine spoke with Lance MacNevin to break down the sizing challenges with plastic pressure piping for commercial applications. BY LOGAN CASWELL
This edition of 30 Mechanical Minutes featured a conversion between HPAC Editor, Doug Picklyk (left) and Lance MacNevin (right) from the Plastics Pipe Institute. MacNevin shared some history of plastic piping along with sizing tips for commercial applications.
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n April 20th HPAC Magazine hosted the latest edition of 30 Mechanical Minutes, the free webinar series featuring virtual content for real world professionals. This edition zeroed in on plastic pressure piping in commercial plumbing, with a focus on the growing adoption of plastic pipes and sizing issues when it comes to design for plumbing and heating applications. The guest for this episode was Lance MacNevin, a frequent contributor to HPAC and the director of engineering with the building and construction division of the Plastics Pipe Institute. This edition was sponsored by IPEX.
HISTORY LESSON To begin, MacNevin shared some background on the early history of plastic piping in the construction industry, which dates back to the 1950s. The earliest residential installations of CPVC plumbing pipes was in 1959, and early-stage development of PEX piping was introduced in the1960s, with fullscale production hitting the European market in 1972 and really taking off in 36
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Canada in the 1990s residentially, and then in the 2000s for commercial applications. Other materials like polypropylene and PE-RT piping were first developed in Europe in the 1980s and introduced in Canada in the 2000’s. From a building code perspective, MacNevin shared that both CPVC and PEX have been in the Canadian National Building Code since the 1990s, and polypropylene was adopted in 1995, while PE-RT appears in the latest 2020 National Plumbing Code released this past March. While most certified plastic pressure piping can be used for commercial systems, some materials are not available in the sizes required. For instance, PEX tubing is widely available in up to 2-in. diameter, while CPVC and polypropylene are made from ½-in. all the way up to 24-in. and 30-in. or even larger. In the field, plumbers will typically choose CPVC or polypropylene (including PP-R and PP-RCT) piping for its rigid characteristics on straight run installations. An example would be the vertical risers in multi-story buildings and horizontal headers of a school or an apart-
ment building or condo. The logic is that you don’t need flexibility along a riser or header, but you do need big pipes and big volume. Then when it comes to branching off to individual classrooms, bathrooms, apartments or hotel rooms, the more flexible PEX or PE-RT are the choice of installation professionals. MacNevin notes that all of the piping approved by the code has pressure rating for continuous operation of 100 psi at 180F giving plumbing installers the ability to seamlessly choose where they want to use rigid piping and where they want to use flexible pressure piping.
SIZING PLASTIC PIPING Clearing up some terminology, MacNevin then clarified sizing issues as tubing and pipe have dimensional differences worth explaining. “We call it all piping, but there actually are dimensional differences between tubing and pipe,” he says, and this applies to plastics and copper and steel piping as well. “Tubing” means the actual outside diameter (OD) is ⅛-in. larger than the nominal size, it’s also known as copper tube size (CTS). “Pipe” means the actual OD matches that of iron/steel pipe HPACMAG.COM
