Abstract: Biaxially oriented poly（vinyl chloride） （PVC-O） pipe segments were heated to make them undergo two disorientation at different degrees of complete disorientation and axial disorientation. Low temperature impact tests were carried out on the finished PVC-O pipe segments， fully disoriented pipe segments， axial disoriented pipe segments， and blank pipes. Axial tensile and radial tensile tests were carried out on the finished PVC-O pipe segments and axial disoriented pipe segments to analyze their mechanical properties before and after disorientation. The results indicated that the low temperature impact and axial tensile properties of the fully disoriented pipes decreased. The low temperature impact and axial tensile properties of the axial disorientated pipes also decreased， but their radial tensile properties showed little change.

Key words: biaxially oriented unplasticized poly（vinyl chloride） pipe, disorientation, mechanical property