Measurement and analysis of friction and dynamic characteristics of PIG’s sealing disc passing through girth weld in oil and gas pipeline

• Dynamic characteristic of PIG’s sealing disc and girth weld during pigging operation.
• A testing rig for measuring the friction force between sealing disc and girth weld.
• A 2D-axial symmetry theoretical analysis model of sealing disc was introduced.
• Simulation results by FEM and ADAMS confirmed the results from experiments.
• The process of sealing disc passing the girth weld can be separated into three stages.

Pipeline inspection gauges (PIGs) are needed for operations such as dewatering, cleaning and internal inspection of the oil and gas pipelines to facilitate improvement in efficiency and safety. The friction and dynamic characteristics, as the sealing disc of a PIG passes through the girth weld in a pipe, has been directly studied using a custom-built experimental setup. The contact behavior between sealing disc and girth weld was analyzed using finite element methods. A two-dimensional section analytical link model of the sealing disc is introduced here and was simulated using the mechanic dynamic analysis software Adams. Our results show that the process of the sealing disc of the PIG passing through the girth weld in the pipe can be separated into three distinct stages: (1) start-up stage, (2) climbing stage, and (3) slope stage. At first, the PIG decelerates due to the friction force and then accelerates after passing through the girth weld. The acceleration and deceleration processes produce axial vibration in PIG.