Abstract
This article presents the results of numerical investigation on modeling buckling behavior and ultimate strength of corroded multi-planar tubular joints. Finite element method was used in order to simulate the behavior of DX multi-planar tubular joints under axial compressive loading.
Three different patterns were chosen for corrosion modeling. Also the effects of corrosion-related parameters such as age and depth of corrosion were evaluated. The first corrosion pattern is based on uniform reduction of wall thickness over a portion of tube length while the second pattern represents a sinusoidal reduction of thickness. The third pattern of corrosion uses average thickness and standard deviation as main parameters for defining a random corroded region. A linear criterion for predicting corrosion wastage has been used for the first and the second patterns, whereas predictions of the third pattern are determined by a nonlinear method.
The results indicate differences in the ultimate strength concluded from different patterns. It was found that conventional methods are conservative in evaluating the strength of corroded tubular joints of jacket platforms. Amongst 3 methods used for modeling corrosion, the third and the second pattern had similar results. It was also shown that corrosion is ineffective in braces and increasing the number of waves for the second pattern will result in increase of joint strength.
The optimum sizes of elements were defined by implementing an analysis of model sensitivity toward element size.
Keywords:
Multi-planar tubular joints; DX joints; corrosion; Finite Element Method (FEM); ultimate strength; jacket platform
