WELD-ON 746 Pool Heavy is for use on all types of PVC plastic pipe pool & spa applications. WELD-ON 746 Pool Heavy is a clear or gray, low VOC emission, heavy-bodied, medium setting, high strength PVC solvent cement for all classes and schedules of pipe and fittings, including Schedule 80, with an interference fit through 12 inches (315 mm) diameter. Can be used on non-pressure applications through 18 inches (450mm) diameter. It has good gap-filling properties and is recommended for solvent cementing joints where a sizable gap exists between pipe and fitting, large pipe sizes, and when more working time is required in warm weather.