Why engineers specify PB-1 for hot and cold water

The long-term hydrostatic strength of PB-1, PEX and PE-RT is determined with the same ISO 9080 extrapolation method, from stress rupture tests at several temperatures. At hot water temperatures, PB-1 shows a higher long-term strength than PEX and PE-RT. That is why PB-1 pipes reach the same pressure rating with thinner walls. The regression curves are in the PB-1 technical paper.

EN ISO 15876 is the product standard for PB-1 hot and cold water piping systems. It covers application classes 1 and 2 (hot water supply at 60°C and 70°C), class 4 (underfloor heating and low-temperature radiators) and class 5 (high-temperature radiators). ISO 10508 defines each class for a 50-year design life at a stated design pressure.

PB-1 resists continuous chlorine at drinking water levels: ASTM F2023 testing shows an extrapolated lifetime of more than 50 years at 60°C and 4 ppm chlorine. Chlorine dioxide shortens the service life of PB-1, as of other polyolefin pipes, especially above 20°C. For chloramine, chlorine dioxide or shock disinfection in hospitals, check the limits of each member system.

PB-1 pipes can have thinner walls because PB-1 has a higher long-term hydrostatic strength per ISO 9080 than other plastics used for hot water pipe. Wall thickness is calculated from that strength and the required pressure rating, so a stronger material needs less wall for the same rating. The result is a larger bore at the same outside diameter.

No single material is best for every heat pump project. The pipe should be easy to lay at close spacing and reliable for the life of the floor. PB-1 offers a small bending radius and high long-term strength at underfloor heating temperatures. PE-RT and PEX are also widely used and can be the more economical choice at low temperatures.

PB-1 is used for district energy service connections, usually as flexible pre-insulated pipe supplied in long coils. It suits lower-temperature networks, where its long-term strength and flexibility allow fast laying with fewer joints. Large-diameter transmission lines at higher temperatures usually remain steel. Check the temperature and pressure limits of each system with its manufacturer.

EPDs and BIM objects for PB-1 piping systems are published by the member manufacturers that make the systems, not by PBPSA. Availability and format differ per manufacturer and per product range. The PBPSA members matrix lists every member system, so engineers can go straight to the supplier whose EPD or Revit library they need.