Procedure Study On The Manufacturing Double Derrick

Offshore derrick is the key equipment in offshore drilling equipment module, not only bear the horizontal loads from the marine conditions and but also the vertical loads during the drilling process, at the same time it support the drilling hoisting device, rotating device, vertical pipe devices, mud treatment device and other equipment on the frame. In order to ensure the derrick with enough strength, stiffness and stability, appropriate ways to control the manufacturing process are needed. In this paper, a set of suitable derrick manufacturing process has been put forward based on the study of the characteristics of offshore derrick structure and technical standard.For better understanding of the manufacturing process of offshore derrick, a dual bottle neck type derrick with hook load 907/400 tons has been selected as the studying object in this paper. Double towers derrick used the truss structure with large size, big span beam, complex equipment, it will be made by single part production, multiple parts transportation, assembling on shipyard, segmented vertical installation, lifting the overall assembly. The main frame of derrick will be made in the workshop and pre-assembled outside of workshop, and inspected the manufacturing quality & accuracy. The construction work of the derrick will be successful completed with the equipment and tools of factory.This paper focuses on the research of welding process and prevents welding crack & welding deformation problem of offshore derrick structure. A satisfied offshore derrick design requirements of welding process and welding quality control measures are obtained through the theory and practice.Offshore derrick can’t be transported after whole assembly because lifting and transportation limitation. In order to ensure the integrity and accuracy of offshore derrick manufacturing, made the research and put forward the suitable pre-assembly process with the circumstances of company facilities based on the characteristics and technical requirement of derrick.