Refractory pipe fittings and production thereof

A method for producing a refractory pipe fitting having a hollow and rigid inner layer made of a synthetic resin, an outer layer made of a refractory material comprising non-metallic inorganic fibers and inorganic binder material, and an intermediate layer made of a flexible foamed synthetic resin interposed between the inner and outer layers for securing these layers and for permitting displacement and deformation of the inner and outer layers relative to each other, comprising the steps of preparing an outer mold internally formed with a molding cavity conforming to the outer configuration of the outer layer, preparing a composite body made up of a shell of the synthetic resin, which is to form said inner layer, and a thin layer of the flexible foamed synthetic resin, which is attached to the outer surface of the shell and is to form said intermediate layer, placing the composite body in said molding cavity to provide a mold gap between the inner surface of the outer mold and the outer surface of the thin layer of the composite body, preparing a mixture of said inorganic fibers and said binder material, kneaded with water, forcibly supplying the kneaded mixture under pressure into said mold gap to carry out a molding operation in which the mixture is adhered to the layer of the flexible foamed synthetic resin, heating the outer mold internally during the molding operation to cause the water in the mixture being molded to be evaporated to form a thin lubricating film of water vapor between the mold and the outer surface of the pipe fitting being molded, and opening the outer mold, after the completion of the molding operation, to take out the molded pipe fitting with said shell attached to the inner surface of the molded outer layer through said thin layer of the flexible foamed synthetic resin.