Post-pass regime at stationary functioning of main gas pipelines

The paper discusses the post-pass regime of gas transport in large-diameter pipelines when there is a directional increase in pressure at negative slopes of the route. When modeling this phenomenon, stationary equations for conveying a real isothermal gas were used, where the pressure gradient was formed under the influence of friction forces, gravity, and the convective component of the gas inertia force. With respect to the pressure gradient, an ordinary differential equation was derived, integrated numerically. The features of the directional change in pressure in horizontal routes (with constant and variable slopes) and in V-shaped routes were discussed. For routes with a constant slope, a formula was obtained to determine the boundary of the post-pass regime.