Risers provide fluid between subsea equipment and surface bodies including platforms, FPS, FPSO or drill platforms. There are several types of risers available, flexible risers steel catenary risers (SCRs) and free standing or top tensioned rigid risers. The most popular riser used in deepwater is the SCR. SCRs provide significant advantages over 'conventional' flexible or 'hybrid' freestanding risers with increasing water depth and riser diameter in terms of weight, induced environment loading and cost. However, their design and long term integrity requires detailed consideration of joint design and fatigue performance over a wide range of loading conditions from the splash zone to the touchdown region and interface to the host installation. Over this range environmental, geometric and mechanical conditions impose varying degrees of tension, bending and fatigue loading; the integrity of the riser will be determined by the response of girth welds to these complex-loading conditions.
TWI has carried out more than 1,000 confidential projects on these topics. TWI also undertakes work to facilitate the installation of SCRs.
Contact: oilandgas@twi.co.uk