June 18, 2024

Answers to the Top Questions Engineers Are Asking about PP-RCT

by Kim Bliss

The requirements for more efficient, sustainable, high-performing and cost-effective structures have brought several new building innovations to the market that help meet the needs of owners, developers, engineers, contractors and, ultimately, end users.

One such solution, polypropylene random copolymer with modified crystallinity and temperature resistance (PP-RCT) piping, is beginning to gain more traction in commercial building design and construction due to its durability, installation ease, economic viability and other important benefits.

Understanding the history, characteristics and design requirements of PP-RCT will help to ensure the product is specified, designed and installed properly for maximum performance in domestic water and hydronic heating and cooling applications.

The following information details key questions engineers may have about the piping system to gain a greater understanding of its properties for confidence in specifying and design.

According to industry standard ASTM F2389: Standard Specification for Pressure-Rated Polypropylene (PP) Piping Systems, the “R” (standing for random) means the material is made up of both long and short molecular chains scattered randomly throughout the material. This random pattern staggers the joints in the molecular bond and greatly increases the ability to withstand elevated temperatures and pressures while also making the material more ductile and resistant to shattering.

PP-RCT is pressure rated for water service lines, hot and cold domestic water, hydronic hot water heating, chilled water, condenser water, geothermal and distribution piping for radiant heating and cooling, snow and ice melting, turf conditioning and permafrost prevention (cold storage) applications.

Some manufacturers offer PP-RCT with a coextruded fiber layer for domestic hot water and hydronic hot water heating applications. This middle fiber layer helps minimize expansion and contraction of the piping system when transporting fluids with larger Delta Ts (temperature differences).

Because most polymer piping systems need to account for linear expansion, this “locked-in” fiber layer keeps the pipe expansion minimal — up to 80% less when compared to nonfiber plastic pipes.

Note that while PP-RCT fiber pipe will expand less than nonfiber polymer piping options, it is going to expand slightly more than steel (about 2.3 inches at a 100°F Delta T over 100 feet).

For more detailed insights, read the full article at CSE Magazine.