The new Canadian limit states pipeline design standard (CSA Z662-96, Appendix C - Limit States Design) incorporates deformation or strain-based design criteria to prevent pipe rupture and or buckling and limit ovality due to bending. These criteria are different and in some instances, much more conservative than those contained in the Canadian offshore pipeline design standard (chapter 11 of CSA Z662-96) and similar standards used in other countries. This study was completed to review the ovality, buckling (including wrinkling) and rupture criteria included in current Canadian pipeline design standards (CSA Z662-96) and define its basic differences with respect to other standards.
The deformation or strain based design criteria formulations in Z662 are compared with those contained in design standards, industry association recommendations and classification society rules from Norway, Britain, Germany, Australia and the USA to illustrate their differences and relative levels of conservatism. In addition, current and on-going research efforts were reviewed to identify the state-of-the-art in pipeline strain-based design, since this research could form the basis for future amendments to existing pipeline design standards.
Based on the findings of this review, recommended changes to the limit states pipeline design formulation are given to better reflect the strain-based (non-linear or post-yield) design and assessment approaches included in the Canadian offshore or foreign pipeline design approaches. In addition, an analytical basis for pipeline ovality and buckling design criteria are recommended.