Breakaway pipe coupling with automatically closed valves

Abstract

A breakaway pipeline coupling is described which comprises first and second pipe sections forming a fluid seal and designed to separate at a predetermined axial load. A plurality of piston and cylinder pressure compensating devices are arranged around the exterior of the pipe sections to hold them together until separation. Shear pins or shear studs passing between the pipeline sections will fail when the coupling is subjected to an external tensile force exceeding the predetermined maximum force. The pressure compensating devices apply a compression load on the coupling to counteract the tension load exerted by internal pressure in the pipeline. The pressure compensating devices included pistons movable axially within cylinders in response to pressure differentials, and porting or tubing for exposing one side of the piston to the internal pressure within the coupling. When internal pressure produces a force which tends to separate the coupling, an opposing compressive force resulting from the pressure acting on the pistons tends to hold the coupling together. External tensile force tending to separate the coupling are resisted by the shear pins, but when a predetermined maximum external tensile force is exceeded, the shear pins fail and the pipeline sections separate. A first, normally closed valve is located within the first pipeline section, and a second, normally closed valve, or a valve lock pin, is located in the second pipeline section. When the pipeline sections are joined together, the valve(s) is locked in the open position and fluid can flow freely through the coupling and the pipeline in which the coupling is assembled. As the sections move relative to one another, each valve is shut to that the contents of the pipeline are not discharged into the environment.

Dependencies are inferred from the claim text.