Abstract
Offshore risers are major assets for oil & gas operator as they represent a significant part of the cost of any offshore project and are relied to transport produced fluids. Furthermore, they represent major Health, Safety, or environmental threats to populations or the environment, if any significant leak or rupture occurs. Therefore any company operating hydrocarbon risers is required to implement rigorous external corrosion management strategy.
For an offshore riser installation, life cycle Riser Integrity Management is essential at design concept, FEED, detailed design, fabrication/construction, execution, commissioning, and operations to ensure the asset is fit for service throughout its service life. Riser external corrosion management is an important aspect of the overall riser integrity management during operation which includes operation preparation, inspection, maintenance and repair. In-service riser external corrosion inspections are to be planned to identify the actual conditions of risers for the purpose of integrity assessment to ensure structural reliability. The benefit of planning and executing maintenance and inspection activities simultaneously cannot be over emphasized.
This paper will describe some specific external localized corrosion issues frequently enencountered in the offshore oil and gas riser systems. The integrity implications and recommendations for addressing these issues both at the concept selection and Front End Engineering Design (FEED) stage as well as during in-service. The paper will also highlight the major benefit of using the correct mix of inspection techiques or tool based on the prior knowledge of the associated corrosion damage mechanisms and the benefit of an optimized preventive and corrective maintenance strategy in the overall life cycle Riser Integrity Management.
