Design Checking And Optimization Of The JJ450/45-K Derrick

Make calculations to JJ450/45-K derrick by means of ANSYS software according to technical drawings, concerning parameters as well as SY/T5609-1999, Basic Parameters for Oil Drilling Rigs, together with API SPEC 4F 6.2 requirements. The whole derrick model consists of 255 nodes, and is divided into 429 beam elements for finite element analysis. Modeling analysis results of the original derrick structure indicates that, the safety factors of 61 and 62 elements, as well as 69, 70, 400, 401, 362 and 363 bar members are not in line with API specified values, with maximum stress as 254 MPa and safety factor as 1.36, all occurred when the original lifting angle is 4.5o (initial state). The bar members are optimized in design without changing the main structure and the optimization result is as follows: the min. safety factor is 1.77 under max. static load, and 2.28 with wind speed as 47.8m/s from the sides, and 2.71 with wind speed as 36m/s, full setback and no hook loads; when the lifting angle of the derrickαis 4.5°, the safety factor is 1.72, which can meet safe operation requirements. The displacement is 172.45mm under maximum static load, and can meet operational requirements; the maximum displacement is 197.15mm with wind speed as 47.8m/s from back direction, and is 185.87mm with wind speed as 36m/s from back direction and full setback, both not appropriate for stripping operations. In addition, when calculated in the optimal design scheme, the static stress, fatigue, stability index of JJ450/45-K derrick are all in accordance with design requirements, and the safety factor reaches above 1.67. The derrick is designed to be reasonable, safe and reliable.