Interference Wear Behaviors of the Pipeline Inspection Gauge Sealing Cups: Experimental Research and Numerical Modeling

In the long-distance pigging operation of natural gas pipelines, severe wear of the sealing cups always leads to the failure and instability of the pig. Different from ordinary conditions, the wear process of the polyurethane rubber (PUR) used in the pigging operation occurs under the condition of interference fit, which generates a continuously varied wear rate. In this research, a custom-built wear experiment was designed and conducted by adopting a specially made indenter and specimen, and then the effect of contact pressure on the wear rate, i.e., the empirical expression of wear rate, was obtained based on the test results and Hertz contact theory. In addition, a numerical model that presents the PUR interference wear behaviors was established by combining the empirical expression of the wear rate and the analytical expression of the hyperelastic materials under the interference fitting. Through MATLAB programming with the iterative algorithm, the wear laws of two kinds of sealing cups were investigated, and the results indicate a coupling induction among the wear rate, wear loss, and contact pressure. The variation of wear loss with traveling distance was proven to agree with the exponential function, and thus a prediction model suitable for engineering practice was built to calculate the wear loss of the sealing cups.