Research On Fatigue Life Evaluation Method Of Offshore Cranes

Offshore crane is one of the most important production equipment and safety equipment for offshore oil exploration and production,usually installed in the drilling and production platform,it always be used to lift goods or personnel for offshore platform or between platforms and ship.As a special equipment,offshore platform crane has a significant impact on the production in the sea,once the key parts of the offshore crane has been damaged,it will result in greater personal injury or property damage.Fatigue failure is one of the most important failure modes of offshore platform crane,which is caused by the long-term load of crane.On this point,this article give a detailed study on the factors of welding fatigue damage mechanism,the damage of the structure form and the influence of fatigue damage;aiming at the special working environment and the use state of the crane on the sea platform,the distribution of the structural fatigue is summarized;analyzing the recommended methods of IIW,DNV and API for the fatigue analysis method,and refers to the methods recommended by several related standards,basic on the cooperation project of our school and the China Classification Society Industrial Company Tianjin Branch "offshore oil cranes(rotary crane)structural evaluation technology research and development",this article choice a crane of the company perform fatigue assessment;analyzed by nominal stress method and hot stress method to get results,analysis and comparison of the two methods,provide guidance for offshore crane fatigue analysis method selection.The main achievements of the paper are as follows:(1)The mechanism of the fatigue damage of the welded structure,the form of damage and its influencing factors are studied in depth.Combined with the use environment and working condition of the offshore platform crane,the distribution of the fatigue behavior of the welded structure is analyzed,which is the fatigue evaluation of the offshore platform crane The selection of the test point position provides a reference.(2)The method of assessing the fatigue life of cranes in two standards of IIW,DNV and API is analyzed,and the recommended methods and calculation steps of each standard for crane fatigue analysis are summarized.(3)Combining the finite element method to establish the offshore platform crane to simulate the vertical elasticity rate,so that the value is more accurate and more targeted.(4)According to the “sea platform crane specifications” under the load conditions and the corresponding load calculation method,at different angles on each crane under the conditions of the most dangerous load combinations calculated.(5)The fatigue life evaluation of the offshore platform crane is carried out by the method of nominal stress method and hot stress method,and the similarities and differences between the two methods are compared,which can provide suggestions for the choice of the fatigue life evaluation method of the offshore platform crane.