Can Limit State Design be used to Design a Pipeline Above 80% SMYS?’, OMAE

ABSTRACT This paper contains the results of a preliminary study, undertaken by C-FER and Andrew Palmer and Associates, for BP Exploration, to demonstrate the feasibility of utilizing limit states design procedures for the design of large diameter, onshore pipelines in remote areas. The objective of the study was to determine if a higher design factor can be justified than that currently specified for such a region; specifically if an increase in the basic design factor, F, from approximately 0.72 to 0.85 could be justified, thereby allowing the pipeline wall thickness to be reduced and a substantial weight saving to be achieved. The work included reliability analyses for three limit state failure scenarios: burst of undamaged pipelines, burst of corroded pipelines and burst of pipelines containing dents and gouges. Results presented show: (1) the calculated probability of rupture for a new pipe (i.e., with no damage, corrosion or other forms of deterioration); (2) the probabilities of failure for pipes containing corrosion or dent/gouge defects; and (3) the effects of a higher design pressure for each limit states scenario. The paper discusses the results, comments on the feasibility of justifying higher design factors and discusses the importance of an appropriate pipeline maintenance management system for monitoring and controlling structural integrity for the full life of a pipeline