Development of a procedure for making inspection plans for corroding oil and gas pipings

Abstract

The degradation of topsides process piping on an offshore platform carrying oil and gas can result in undesirable events like bursts and leakages. In order to manage the challenges arising from such failures, the piping is regularly inspected using different types of Non Destructive Testing (NDT) methods. Since this piping has different configurations and is often located in places that are difficult to access, the associated costs of these activities are quite high. To support the decision-making on the development of an effective and efficient inspection programme, Risk-Based Inspection (RBI) analysis is often used. Based on the recommendations of the RBI analysis, the inspection is carried out and the results of the inspection are then reinvested into the inspection management programme to update the analysis.

This thesis presents a methodology based on Bayesian updating to formally ensure that experience and knowledge are used in a systematic way, when deciding how much needs to be inspected in order to be convinced that the corrosion group of components does not contain any significant corrosion. It is expected that the implementation of the methodology will improve the inspection management by providing a systematic tool to incorporate the inspection results, provide traceability and reveal critical assumptions. This thesis will also present a method for how to evaluate and communicate different uncertainty factors.