A tubular product has a tubular base layer, a tubular innermost layer made of plastic by continuous extrusion, and a tubular tie layer of foamed plastic between and adhered to the base layer and the innermost layer. The tie layer is made of melt processable adhesion plastic, is extruded simultaneously with the innermost layer against the base layer, and has better adhesions to the base and innermost layers than the base and innermost layers have to each other.