Polypropylene (PP) is a versatile piping material that is used in a wide range of applications. Two types of PP are used for pressure piping systems: PP-R (polypropylene random copolymer) and PP-RCT (polypropylene random copolymer with modified crystallinity and temperature resistance).
With their high temperature and pressure capabilities, PP-R and PP-RCT pipes are suitable for demanding pressure piping applications, such as pressure piping (plumbing, hydronics) in commercial high-rise buildings.
PP-R pipes are also used in non-pressure applications, and provide resistance to highly acidic and basic solutions, such as corrosion inhibitors and chemicals used in hydronic heating and cooling systems. Joints are typically heat fused following standard industry practices.
PP-R and PP-RCT pipes come in metric sizes ranging from 16 to 710 mm, also known as nominal diameters 3/8 to 28. The minimum hydrostatic pressure ratings are typically higher for PP-RCT materials, but pipes with different dimension ratios (DRs) and wall thicknesses can have higher or lower pressure ratings.
PP-R and PP-RCT pipes and fittings are completely compatible with each other. PP-R pipe can be fused to PP-RCT fittings and vice-versa.
PP pipes may include reinforcement layers of chopped glass fibers for benefits such as reducing longitudinal thermal expansion/contraction.
PP-R and PP-RCT pipes are typically sold in straight lengths. PP-R is also available in coils for smaller diameters and specific applications.
PP-R
Definition
According to the definition found within industry standard ASTM F2389 (first published in 2004), PP-R means “polypropylene random copolymer”. PP-R is a copolymer of propylene and at least one comonomer, where the propylene is more than 50% of the composition.
Overview
PP-R is a high-temperature plastic pressure piping system first used for plumbing and hydronic heating in the 1980s in Europe and introduced to North America in the 2000s. PP-R was first used for various industrial applications in the 1970s in Europe, and the first reported usage of PP-R in North America for industrial uses was in 1986.
When SDR 9 (or thicker) wall type is selected, these materials are rated for 100 psi at 180ºF (690 kPa at 82ºC), meeting the requirements of national plumbing and mechanical codes. The actual pressure ratings of PP-R pipes depend on the selected wall type or thickness.
PP-R piping materials are available in various wall types and thicknesses (e.g., SDR 7.4, SDR 9, SDR 11, SDR 13.5, etc.), depending on the required pressure rating. Thicker-walled pipes have higher pressure ratings, and thinner-walled pipes have lower pressure ratings. Consult the specific PP-R pipe manufacturer's literature and listings for appropriate pressure ratings.
PP-RCT
Definition
According to the definition found within industry standard ASTM F2389 (first published in 2004), PP-RCT means “polypropylene random copolymer with modified crystallinity and temperature resistance”. PP-RCT is a copolymer of propylene and at least one comonomer, where the propylene is more than 50% of the composition.
Overview
PP-RCT is a high-temperature plastic pressure piping system first used for plumbing and hydronic heating in the 2000's in Europe and North America.
PP-RCT is a newer generation PP-R material with higher long-term strength at elevated temperatures than earlier PP-R 80 and PP-R 100 resins. PP-RCT material has approximately 25% higher stress capability and a 25% higher pressure rating than PP-R pipes for the same wall thickness at a given operating temperature.
Commercially available PP-RCT resins may be either alpha-phase crystallinity or a combination of alpha and beta phase crystallinity by use of a beta nucleating agent.
When SDR 9 (or thicker) wall type is selected, these materials are rated for 100 psi at 180ºF (690 kPa at 82ºC), meeting the requirements of national plumbing and mechanical codes. The actual pressure ratings of PP-RCT pipes depend on the selected wall type or thickness.
PP-RCT piping materials are available in various wall types and thicknesses (e.g., SDR 7.4, SDR 9, SDR 11, SDR 13.5, etc.), depending on the required pressure rating. Thicker-walled pipes have higher pressure ratings, and thinner-walled pipes have lower pressure ratings. Consult the specific PP-RCT pipe manufacturer's literature and listings for appropriate pressure ratings.