Insulated pipe-in-pipe riser system and bends

Recent developments in the United Kingdom Continental Shelf have set new precedents for temperature and pressure requirements in rigid riser systems. In a recent pioneering development for example, riser materials were exposed to extremes of temperatures ranging from 180 °C down to -30 °C in certain well conditions. Other challenges included high pressures; corrosive well fluids and tight project timescales. As a result of these extraordinary conditions the riser system required a unique blend of new technologies, combining to deliver a riser arrangement of the highest integrity. One of the most significant challenges in the riser system was the supply of pipe in pipe bends. Tata Steel worked closely with supply partners Eisenbau Kramer and Salzgitter Mannesmann Grobblech to engineer, procure and construct these bend assemblies. This article defines the challenges that were faced by the design team and illustrates the technologies that were implemented to overcome each one.