Patent ID: 8715423

Claim:
A pig for movement within a pipeline comprising: a cylindrical housing; at least first and second annular elements circumferentially mounted to the housing and extending outwards for engagement with a pipeline; an internal flow cavity passing longitudinally through the housing; a gate extending diametrically across the internal flow cavity and connected to a shaft, the gate capable of rotation about the shaft and capable of being opened by fluid pressure in the internal flow cavity, the gate positioned in a medial position within the internal flow cavity, obstructing flow through the internal flow cavity; a retaining device connected to the gate, preventing it from being opened, the retaining device being releasable to release the gate so that fluid pressure in the internal flow cavity opens the gate by causing the gate to rotate about the shaft in the event the pig becomes stuck; and a sensing device capable of receiving a signal indicating the pig is stuck in the pipeline, thereby releasing the retaining device, permitting the gate to open.