PURPOSE: To obtain cement mortar pipes which are excellent in strength, heat resistance and chemical resistance by covering the inner surface or the outer surface of the cement mortar pipes with vinylidene chloride resin.

CONSTITUTION: The inner surface of the cement mortar pipe 1 is covered with vinylidene chloride resin 2. The vinylidene chloride resin 2 is a copolymer of about 85-95% vinylidene chloride and acrylic ester, methacrylic ester, acrylonitrile, vinyl chloride or the like. In order to improve the gas barrier, vinylidene chloride is preferably more than about 60%. The cover may be formed by pressure forming after injecting vinylidene chloride latex on the inner surface of the cement mortar pipe, or pressure forming after dipping the pipe 1 in vinylidene chloride latex.