부산대학교 도서관

When pipeline relocation is necessary, it is a common practice for pipeline operators to move the line while it contains gas or liquid product under pressure in order to avoid taking the line out of service. Reasons for this practice include lowering to accommodate a new crossing, raising for repair or recoating, or moving to avoid encroachment. Such operations increase the longitudinal stresses in the relocated section of pipeline. Usually, this has not caused significant problems. However, at least four pipeline failures have been associated with the movement of pipelines over the years. On October 22, 1991, the DOT Office of Pipeline Safety issued an `Alert Notice` to US pipeline operators urging them to conduct analyses prior to moving a pipeline, regardless of whether the line is in service during the operation or not; to determine the extent to which a pipeline may be safely moved, considering the material toughness as a factor; and specific procedures for the operation. The notice resulted from recommendations by the National Transportation Safety Board following their investigation of the North Blenheim failure. This document in intended to be a reasonably comprehensive manual for engineering a safe relocation of an operating pipeline in service. The major elements of the desired guidelines were perceived to already exist in various industry guidelines, standards, proceedings, and research reports. Those sources were compiled, compared and distilled into recommendations for designing a safe line relocation. This manual supplements existing guidelines such as API RP-1117 rather than superseding them; indeed, the user of this document would benefit by referring to them as well. Observance of recommendations made herein should satisfy the nominal requirements and concerns of regulators. However, this document could not possibly address every conceivable situation which might arise in line relocation, nor is it a substitute for independent engineering judgement.