Card sleeve joints are widely used in the connection of hydraulic and pneumatic equipment such as oil and gas pipelines, and its connection reliability has an important impact on the safety of oil and gas pipelines. However, there is no report on the influence of external working conditions on the stress characteristics of the thread of card sleeve joints in oilfield ground pipelines. A three?dimensional model of the double card sleeve joint was established using SolidWorks software; The maximum equivalent stress (Von Mises stress) of the sleeve joint was numerically analyzed using ANSYS finite element software. The results indicate that within the yield limit, the greater the axial force, the better the sealing performance of the sleeve joint, while the internal pressure has little effect on the sealing of the pipe joint, and the risk of thread sticking due to excessive stress can be ignored; The influence of thread parameters on sealing performance is significant; The optimal pitch and number of threads for a sleeve joint with an outer diameter of 12 mm and an inner diameter of 9 mm are 1.5 mm and 7, respectively. The research results can provide theoretical basis and reference for the optimization of structural performance and scientific operation in the assembly process of card sleeve joints, which has important engineering significance.

The geometric model of a certain oil and gas mixed transportation pipeline was established with OLGA software, and the transient flow law during the pipeline shutdown and restart process was studied. First, the distribution characteristics of temperature, pressure and liquid holdup along the pipeline during steady state operation were analyzed, and the location of the minimum temperature and the location of the maximum pressure along the pipeline were determined. The influence of environmental temperature and shutdown time on operating parameters were analyzed. The safe shutdown time when the minimum temperature temperature is higher than its freezing point was determined. In the actual operation process, the shutdown time should not exceed the safe shutdown time, otherwise problems such as pipeline condensation and excessive starting pressure will easily occur, which threaten the safety of the pipeline.