The Construction Technology Research For Legs Of Jack Up Platform

As one of the mainstream products of offshore platform family,jack-up platform plays an important role in offshore marine exploration and development.Every shipyard has turned its attention to this field,among which the construction and installation of pile legs is the most critical and difficult work in the construction of jack-up platform.Whoever has mastered this key technology can open up a world in this field.However,due to the limitation of domestic technology level and monopoly of foreign technology,some core components of pile legs have to rely on imports,which increases the manufacturing cost of the platform.This paper mainly studies several main technical problems and solutions encountered in the construction of pile legs.First of all,the rack cut by traditional flame cutting technology often encounters defects such as non-vertical incision,convex and concave cutting surface,slag hanging,cracks and so on.Usually,it can meet the use requirements through complex post-processing.Through the analysis of flame cutting quality defects and the factors affecting flame cutting,the parameters and environment of cutting equipment are optimized.The cutting quality of the rack has been greatly improved and the design requirement has been met at one time.Secondly,the commonly used cold-pressing technology of half-chord and seamless steel pipe cutting technology are changed to hot-pressing technology.Through upgrading the existing press in the shipyard,a movable large hot-pressing die is designed,which can produce an economical and practical half-chord with a length of up to 8 meters,thus solving the problem that the cold-pressing technology needs a large press and the stress can not be released,and is prone to cracks.The problem of short pressing half chord by traditional hot pressing technology is also discussed.Thirdly,a large number of bulk parts need to be installed in the closure stage,especially the bottom horizontal support pipe oblique support pipe,which needs to be packed in bulk in the dock.The construction space is relatively narrow,the environment is harsh,the difficulty of joint assembly,welding and flaw detection is very high.By adjusting the segment of pile leg and pile boot reasonably,the construction space is very narrow.The division makes a great deal of workload in the closure stage move forward to the construction of pile legs and pile boots,which greatly reduces the workload in the closure stage,greatly improves the construction conditions and improves the welding quality.Finally,by means of construction subsection,lifting subsection,closure subsection,slide of guide rail,closure positioning and other technological means,relying on simple and safe tooling,the closure of pile legs of 400 ft jack-up offshore platform can be ensured smoothly,so as to solve the problems of leasing large-scale sea crane,long closure time,low efficiency and high cost for existing platform pile legs closure.