ABSTRACT The integrity of pipelines in operation is typically verified by integrity management programmes. This involves a four step procedure considering risk evaluation of potential pipeline failure, monitoring, testing and surveys, and an assessment of the pipeline's integrity. Based on the integrity evaluation, actions to mitigate or remove the damaging response may be initiated. The present paper focuses on the integrity assessment which is performed after the survey campaign. Methods for analyzing the integrity of pipelines based on information from external surveys are presented. This is displayed together with a new analysis tool developed by REINERTSEN AS. The methods are verified extensively by FE analysis and are applied in all levels of integrity assessments, i.e. qualitative assessment, screening and detailed analysis.
NTRODUCTION AND BACKGROUND Subsea pipelines and structures shall conform with specific design criteria during both design engineering and after being put into service. This implies that the operational history must be followed up to ensure that the pressure and temperature loads conform with design criteria, and that the pipeline is responding as expected, e.g. lateral buckles, free-spans and upheaval buckles. Any change in operational conditions requires further design assessments and re-qualifications of the pipeline system. Guidelines for integrity management are presented in e.g. DNV-OS-F101 and DNV-RP-F116. Ideally, the Integrity Management Philosophy should be developed taking into consideration the design of the pipeline and how the integrity of the system should be managed and reported. This is presented in the DNV recommended practice no F116 (DNV-RPF116). Briefly described, the overall integrity management rationale follows a periodic procedure consisting of Risk assessment and IM planning, Inspection and monitoring, Integrity assessment and Intervention and repair. The integrity management process is illustrated in Figure 1. (Figure 1 is shown in the paper)