Full-Scale Fatigue Test Technology Research On Multiple Welding Joints Of Marine Riser

The strength and safety of riser serving as common marine pipeline structure is vital for ensuring the safe operation of the offshore drilling operation.Among many infection factors which give rise to marine riser accidents,fatigue damage is determination and welded joint is critical part.In order to ensure the safe operation of the marine riser,and reduce the pipeline rupture and leakage accident,it is necessary to evaluate and analysis the fatigue performance of marine riser.At present,the domestic study of Marine riser fatigue test is still in its basic stages.In foreign countries,the analysis to riser fatigue test more adopts the small size specimen,but it ignores the size effect and releases the welding residual stress,leading the test result on the high side.Riser full-scale fatigue test methods adopt a single joint specimen to test and analyze,and the test cost is high,the cycle is long,the test results are greatly random and disperse.In view of this,this paper establishes a full-scale fatigue test method on multiple welding joints of marine riser and completes the full-scale fatigue test on multiple welding joints of ?323.9mm×18mm marine rise.Finally it concludes its R-S-N curve,which lays a foundation for its fatigue performance evaluation.The research contents are as follows:(1)By comparing the small size of fatigue test and full-scale fatigue test,and compared all kinds of loading ways of the fatigue test,put forward of the Marine riser by four-point bending mode full-scale fatigue test which can more accurately reflect the riser's actual life.(2)It accomplished bending test,tensile-strength test,impact test and hardness test on the full-scale fatigue test,and sample's welding groove is double “V” composite groove type,the welding technology is the STT gas protection semi-automatic root welding and self-protection flux cored wire semi-automatic welding.(3)Considering riser welding joint stress concentration phenomenon,it measures related parameters and calculates the stress concentration factor for the correction of the full-scale fatigue test stress amplitude,making the results more accurate for practical engineering application.