Reliability-Based Design Method For Submarine Pipeline And Its Programming In Installation

Submarine pipeline is one of the most important, quick, economical and reliable manner for offshore oil and gas transportation, which is widely used nowadays. Since the first submarine pipeline in the Gulf of Mexico was installed in 1954, a great number of submarine pipelines with various calibers and types have been successfully installed in offshore all over the world. Using submarine pipeline as a way to transport submarine oil and gas has been becoming more and more common.So far, most of the submarine pipelines in China have been designed according to the Code of DnV1981, and the stress and strain of pipes during installation have been calculated by the OFFPIPE (1996) software. As the development of submarine pipeline's design code, detection technique inside-outside, installation techniques and all kinds of the corresponding analysis software, the limit-state design standard-DnV OS F101 Code will be gradually used in domestic submarine pipeline designs.Latest researches on submarine pipeline design, installation and detection as well as the basic theory used in the submarine pipeline design and construction are summarized in this paper. The strength design approach of pipeline in DnV OS F101 is analyzed, and the method and process for submarine pipeline strength design are summarized in comparison with DnV1981. Based on the new design code, an evaluation of an old pipeline, which was designed under the DnV1981 and has been used for many years, is carried out by reliability theory.<> (Version 2000) is an object-oriented software for analyzing the stress and strain of pipelines during installation. The software has independent intellectual property by Structural Engineering Institute of Zhejiang University. With the introduction of new design code, SPLAS 2000 needs to be upgraded. A new calculation function for wave theory and laybarge motion theory based on original program is appended to it. In the upgraded SPLAS, user can choose a suitable wave theory to calculate wave forces subjected to submarine pipeline and output the equation of laybarge motion in waves. By reading the calculation result files of OFFPIPE and checking the internal force and stress-strain of pipeline during installation according to DnV OS F101, the program makes OFFPIPE (1996) suitable for the new code.