12mm x 1.6mm Pert-AL Pipe Water Underfloor Heating System. High Specification Pert-AL Pert pipe 12mm diameter with 1.6mm wall, each roll is 80m or 160m. Service temperatures: 40°C - 85°C Maximum constant 70°C Working pressure: 10bar Five-layer composite pipe combines the benefits of both metal and plastic pipes aluminium core prevents ingress. 25 Year Manufacturer's Guarantee.