Development of High Strength 100 ksi Seamless Weldable for Deepwater Riser Application

The deepwater and ultradeepwater production and exploration technical demands are increasing on a daily basis. The benefit of having pipes with high strength and reduced wall thickness is very well recognized by all the oil community. In order to develop a high strength seamless 100 ksi weldable riser, a Joint Industrial Development Program (JIP) was launched in 2003. This paper describes the results of the first phase of this JIP, devoted to the development and production of seamless 100 ksi pipes. A detailed metallurgical analysis, including the role of chemical composition and quenching and tempering process conditions on the microstructure and precipitation was performed. The influence of the type of microstructure on strength, toughness and fracture mechanics behavior was studied in detail for both laboratory and industrial materials. The 100 ksi grade was accomplished for seamless pipes with wall thickness of 16 mm and 25 mm. The second phase, devoted to evaluate field weldability of this new product, is in progress.