Identified In The Analysis Of The Carrying Capacity Of The Type A Derrick And Its Defects

An oil derrick is a necessary supporting frame, and plays an important role in oil production. 'A' form derrick is in extensive use. The workers take attention on it's carrying capacity. Nowadays, the study of derrick usually is about it's intensity, some initial defects are not considered. Didn't think about the effect to the carrying capacity.Some initial defects are considered and studied. Deducing the equivalent formula of the initial defect. The finite element analysis software (ANSYS) is applied to establish the model of 'A' form derrick. Based on the design feature of the derrick, the actual derricks structure is idealized an assemble of space pipe element and space beam element, and carry out the static, dynamic analysis and stability analysis. Calculates the max load. Depend on the conditions in oil production, put forward a test method for the most important initial defects, and deduce the formula.In this paper, the author takes JJ170/41-A form derrick for example. To obtain practice result of the derrick's load capacity, both the dynamic and static stability and behavior should be taken into consideration. The result of the calculation can offer reference basis to designing and evaluating the load carrying ability of the derrick. The method for initial defect can offer the test of derrick.