Molecularly Oriented Polyvinyl Chloride PVCO
PVCO pipe, which stands for molecularly oriented polyvinyl chloride pipe, has been utilized in North America for over four decades, boasting an impressive track record with more than 20,000 miles of pipe installed. Similarities between PVCO and traditional polyvinyl chloride (PVC) pipe exist, including shared ingredients and cell classifications. Initially, PVCO begins as an equivalent PVC compound, undergoing extrusion into PVC pipe before undergoing physical modification to transform into molecularly oriented pipe. Consequently, both PVCO and PVC pipes qualify for cell class 12454 per ASTM D1784 and boast a hydrostatic design basis (HDB) of 4,000 psi. The manufacturing process for PVCO involves realigning the molecular structure from random orientation to circumferential orientation, thereby enhancing the material's mechanical strength and toughness.
Once completed, PVCO pipe achieves an impressive HDB of 7,100 psi. Due to the differing HDB values of PVCO, conventional PVC's dimension ratio (DR) classification is not applicable, with PVCO being solely referenced by pressure class (PC) or pressure rating (PR). In North America, Cast Iron Outside Diameter (CIOD) products range from 4 inches to 30 inches in pressure classes 165, 235, and 305 psi, while Iron Pipe Size (IPS) products are available in sizes ranging from 4 inches to 16 inches with pressure ratings of 160, 200, and 250 psi.
PVCO and PVC find common application in distribution systems requiring open-cut installations, with PVC additionally suitable for trenchless installations. The inaugural North American installation of PVCO pipe transpired in Kansas in 1979, following its development in Europe during the early 1970s and first installation there in 1974. By the 2000s, multiple manufacturers offered PVCO pipe in North America. ASTM F1483, published in 1993, marked the initial product standard for PVCO pipe. Early applications predominantly focused on rural water and irrigation piping. Subsequently, in 1998, AWWA C909 emerged as the first PVCO municipal water pipe standard, drawing from AWWA C900 in terms of requirements, safety factors, diameter regimen, product quality control testing, and joint qualification testing. Over the years, AWWA C909 has undergone updates to encompass larger sizes and align with revised design procedures from the C900 standard. In 2009, CSA published PVCO standard B137.3.1, further solidifying the standing of PVCO pipe within the industry.
