Abstract: Pipe insulation means for installation around a pipe to cover at least part of the surface thereof comprises two elongate preformed insulating members each comprising a cast refractory insulating material. The two members are hingedly connected together at adjacent radial longitudinal faces, and a cast refractory wedge member is inserted into a wedging groove preformed in the said faces of the members radially outwardly of the hinge whereby the opposite longitudinal edges of the members are urged closer together as the wedge member is driven home into the groove to force the members against the surface of the pipe and cause them to grip the pipe so tightly that other means of fixing, and in particular welding is unnecessary.