12mm x 1.6mm Pert-AL Pipe For Water Underfloor Heating System. High Specification Pert-AL Pert pipe 12mm diameter with 1.6mm wall. Service temperatures: 40°C - 95°CMaximum Working pressure: 10bar Five-layer composite pipe combines the benefits of both metal, and plastic pipesAluminium core prevents ingress. 25 Year Manufacturer's Guarantee.