Based on a new expansion technology for oriented polyvinyl chloride (PVC-O) pipes, the stress distribution in pipe wall during expansion and the efficiency of the heating process are analyzed theoretically. According to the results of theoretical calculation, the optimal parameter and strength variation for different expansion ratios are studied experimentally. Theoretical calculation results show that the hoop stress and radial stress in pipe wall are near-linearly distributed, and they are approximately equal. The heating efficiency is gotten by heat transfer calculations for different oil bath temperatures and heating times. After expansion, the intensity and Young's modulus are increased but elongation at break is reduced. All the variations in properties enlarge along with the raise of expansion ratio. Fine appearance and high-strength PVC-O pipe can be achieved by optimizing the expansion parameter. (C) 2009 Wiley Periodicals, Inc. Adv Polym Techn 27: 172-181, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20137