Pipeline pig launch pin and retraction system
View Patent ↗A method and system for launching a pipeline pig includes the steps of compressing a modulating bypass valve of a pipeline pig and installing a locking means to temporally maintain the bypass valve in the compressed state. Once the pig has travelled a predetermined distance through the pipeline, the locking means is released and retrieved through the launch trap door. The locking means is preferably a launching pin having a clip attachment that receives the clips of a retractable lead. The lead is housed by a retraction device that is detachably secured to the launch trap door. The modulating valve has sufficient mass and aerodynamic drag to overcome the force of a gas spring. The valve moves between a retracted and compressed position substantially instantaneously upon the pipeline pig stalling and between the compressed and retracted position substantially instantaneously upon the pipeline pig accelerating.
1. A method for launching a pipeline pig, the method comprising the steps of:
compressing a bypass valve of a pipeline pig so that the bypass valve is in a compressed position that provides for a predetermined bypass flow;
installing a locking means to temporarily maintain the bypass valve in the compressed position;
inserting the pipeline pig into a launcher connected to the pipeline;
launching the pipeline pig for travel through the interior of the pipeline;
removing the locking means after the pipeline pig has travelled a predetermined distance through the interior of the pipeline; and
retrieving the locking means through the launcher.
2. A method according to claim 1 further comprising the locking means being a launching pin.
3. A method according to claim 1 further comprising the step of retrieving including the step of attaching a retrieval means to the locking means.
4. A method according to claim 3 further comprising the retrieval means being a retractable lead.
5. A method according to claim 1 further comprising the predetermined distance being a distance greater than a distance between the starting position of a rearward end of the pipeline pig and a first mainline valve and bypass tee of the pipeline.
6. A method according to claim 1 further comprising said step of compressing including the step of moving the bypass valve between a first position and a second position, the first position allowing a maximum bypass flow through a venturi of the pipeline pig, the second position allowing a minimum bypass flow through the venturi of the pipeline pig.