Acceptance criteria of defects in undersea pipeline using internal inspection

The purpose of this paper is to establish acceptance criteria for interpretation of the internal inspection results of undersea pipelines. There are no specific rules or guidelines for the acceptance criteria of existing pipelines using a certain internal inspection method. Acceptable criteria were established with a case study of a 609.6 mm (24 in.) diameter, concrete weight coated pipeline delivers fuel oil to a thermal power plant, Ghana. Parameters to be considered in the uncertainties of flaw sizing include the crack length, depth, orientation of the flaw, whether or not the flaw is surface breaking, and number of flaws. Fitness-for-services of other pipelines can be determined using the established criteria in this study. The method of inspection also affects the acceptance criteria. Imposing limitations at or beyond the limits of detection capability would obviously be counter-productive.