Assessment Method Research For Fatigue Life Of Subsea Pipelines

With the rapid development of the offshore oil industry, subsea pipelines arewidely used in offshore oil and gas exploitation thanks to many advantages, such ascontinuous transportation, big transporting quantity, convenient management, andsafety. Due to the highly complex environmental conditions under which subseapipelines are, the damage to pipelines will lead to suspension of exploitation andsevere economic loss because of the long period and high cost for repair. At the sametime, the leakage of oil and gas caused by damage will result in the seriousenvironmental pollution. So damage to subsea pipelines has attract the attention ofdomestic and international researchers and become one of academic hot issues allover the world. Free spans will occur due to the fact that subsea pipelines are scoured by waveand current and easily be destroyed by fatigue effect without the support of soil. This paper studied the assessment method for fatigue life of subsea pipelinesaffected by current under the combined wave and current condition, and worked outthe calculating process of subsea pipeline fatigue life based on Miner linear damagecumulating theory and assessment model in DNV RP－F105. Numeric experiments based on the 12″interfiled pipeline of DF1-1 GAS LINEare made by using method established, the effects of parameters on fatigue life arealso specified.