Static stability of gas pipeline

Hydroelastic systems can be characterized by the simultaneous manifestation of elastic and hydrodynamic instabilities and their interaction. Consideration is given to mutual effects of gas pipeline bending, internal and external pressures, action of the compression force and fluid with a set density flowing along the pipe, axisymmetric expansion of a pipe and its longitudinal shortening, change of temperature of a wall of a pipe. The smallness of inertial forces is conditioned by a relatively slow change of disturbances under slowly changing external effects (compressive forces in the pipe, hydrostatic forces, velocity of gas motion in the pipe). External effects can be both independent and interconnected with each other. Here, the static mutual influence between those instabilities is called the instability interaction in a gas pipeline. We have obtained the linearized equation of the gas pipeline bend and the critical value of the force that squeezes the gas pipeline, which represents a generalization of the classical critical value for the static longitudinal compressive force acting on the pipe in the Euler problem due to the action of pressures inside and outside the gas pipeline and the gas motion inside the pipe, axisymmetric expansion of a pipe and its longitudinal shortening, change of temperature of a wall of a pipe. The investigation is focused on static instability interactions depending on the compression force in the gas pipeline, internal and external pressures and gas velocity, axisymmetric expansion of a pipe, change of temperature of a wall of a pipe. Bending rigidity, tensile forces and external hydrostatic pressure stabilize the pipe. By contrast, compressive forces, internal hydrostatic pressure and gas movement inside the pipe at any velocity, increase in temperature of wall of pipe have a destabilizing effect.
Materials and methods
Consideration is given to static stability of gas pipelines. The author uses the equation of bend a pipe according to the Kirchhoff’s model and boundary conditions for a gas pipe clamped at both ends.
Results
The investigation outcomes can be applied for a research of static stability of the designed gas pipeline.
Conclusions
Bending rigidity, tensile forces and external hydrostatic pressure stabilize the pipe. By contrast, compressive forces, internal hydrostatic pressure and gas movement inside the pipe at any velocity, increase in temperature of wall of pipe have a destabilizing effect.