Optimization The Secondary Welding Work Of NO96 LNG Cargo Containment System

LNG is called Liquefied Natural Gas.Natural Gas is purified and cooled to-162~oC under normal atmospheric pressure,it turns from Gas to liquid and 1/625 of its volume when it turns into Gas.The ship carrying LNG is called LNG carrier,which is a special ship carrying LNG from the supply place to the use place.Welding work of the secondary NO96 cargo containment system is welding all kinds of metal parts in the cabin together.Welding quality requirement is strict,and both argon arc welding and resistance welding are used.Welding work directly determines the completion time of the cargo containment system.The penalty for delayed delivery is USD 150,000/day,and there is no discount for delayed delivery.Therefore,the optimization of welding work is to ensure the high-quality and efficient completion of welding work,which is necessary for the timely delivery of LNG ships in H shipyard.In the study of NO96 secondary layer welding work,this paper analyses the problems existing in the welding work.On the basis of the theory of TOC(Theory of Constraints),welding DBR(Drum-Buffer-Rope)model is established,and using optimization schemes and steps of the TOC theory,optimize the containment system welding work.The specific research work of this thesis is as follows:This paper describes the background of the topic selection,the research status of the welding work of the envelope system at home and abroad,the significance of the paper research,and the application of TOC theory in production;This paper introduces and analyzes the sub-layer welding work of NO96 LNG ship enclosure system,finds the existing problems in the welding work,and analyzes and studies the application of TOC theory in the welding work;Establish the TOC DBR model to analysis the bottlenecks in the process of production.The method could also provide the solution of the bottleneck,this chapter will apply DBR model of the containment system layer welding work,and refined to each specific work,eventually establish DBR model of containment system welding layer,finally to solve the bottleneck problems existing in the DBR model by applying five improvement method.Based on the theory of TOC optimization,improve the bottleneck of the secondary layer welding work by seven plan.And analyze the bottleneck problem of welding the strake-end,choose the best combination of welding personnel and equipment to finish the welding work by using orthogonal calculation method,and guide the production.Use experiment method to choose the correct parameters of the anchoring bar repair process,and solve the bottleneck problem in production.