GRE pipes offer a unique combination of high mechanical, thermal and chemical resistance which is obtained by the selection of high performance components and a proper design of the structure. The inner liner, which is made by a resin rich layer reinforced with C-glass or synthetic veil, guarantees the pipe water tightness, its chemical and temperature resistance. The mechanical resistant layer is composed of successive layers of pre-stressed glass roving impregnated with epoxy resin and orientated with a precise, predetermined angle selected in order to achieve the properties required. The resin and the hardener system are selected with the consideration of the combination of properties required from the finished product. The glass reinforcement in the form of continuous roving is chosen base on its compatibility with epoxy resin. It is applied on the rotating mandrel following the hoop (radial) winding pattern combined with a helical winding pattern at an angle ranging from 45° to 90°.
Glass tape or unidirectional reinforcements can be used to obtain local reinforcement. An external resin coating reinforced with a synthetic veil adds a finish to the pipe. Should weathering be a problem a UV inhibitor will be added to the coating.
GRE pipes are generally manufactured with an integral joint, which means that the socket (for bonding, lock, or thread) is produced simultaneously with the pipe body by winding on a specially designed metallic mould fixed at one end of the mandrel. The pipes are wound on precisely machined steel mandrels, the mandrel is extracted only when the pipe is cured.