Abstract: Similar transfer units are disclosed for launching pig balls into a pipeline and for receiving the pig balls from a downstream portion of the pipeline, each of the transfer units including a hollow housing providing an axially aligned manually or hydraulically operable valve member and valve seat for closing off a magazine which is inclined from horizontal to permit gravity transfer of the pig balls, the hollow housing being otherwise shaped to facilitate transfer of the pig balls. With a pair of the transfer units being connected with a pipeline, the launching unit includes controlled plungers for regulating passage of individual pig balls into the pipeline while the receiving unit at the downstream portion of the pipeline is arranged for directing the pig balls into the receiving unit. A magazine housing for each unit is separable from the hollow housing to facilitate replacement of the valve seat.

Abstract: The valve spool of a three-way pilot valve responds to changes in pressure in a pipeline downstream from a shut-off valve that is biased to close by spring pressure and has a control cylinder to admit pressurized control fluid to open in opposition to the spring pressure. When the pipeline pressure is in the normal range the valve spool is at a normal position where it places the pressurized control fluid in communication with the control cylinder of the shut-off valve to keep the shut-off valve open. When the pipeline pressure drops below the normal range the valve spool moves in one direction from its normal position to a first alternate position to cause the shut-off valve to close and when the pipeline pressure rises above the normal range the valve spool moves in the opposite direction to a second alternate position to cause the shut-off valve to close.

Abstract: A shut-off valve in a fluid line closes by spring pressure and incorporates a control chamber wherein pressurized control fluid acting on a piston opens the valve in opposition to the spring pressure. A control system for the shut-off valve comprises a 3-way actuator pilot of the present invention in cooperation with a monitor pilot. The actuator pilot has a valve spool and four ports, namely, a supply port connected to a source of pressurized control fluid, a pilot port connected to the monitor pilot, a control port connected to the control cylinder of the shut-off valve, and an exhaust port for venting the control chamber of the shut-off valve. When the control system is in service and the monitor pilot senses an undue change in the pressure in the fluid line, the monitor pilot vents the actuator pilot to shift the valve spool therein to cut off the control fluid from the control port and simultaneously to place the control port in communication with the exhaust port to cause the shut-off valve to close.

Abstract: A housing structure confines a ball-shaped valve member with a flow passage therethrough. One end of the flow passage serves as a cavity to receive a pipeline scraper in the form of a pig ball and a grid retains the pig ball while permitting fluid flow through the passage. The valve ball cavity may register with the chamber of a normally closed magazine to receive a pig ball therefrom or to release a pig ball thereto. The valve ball cavity may also register with one of the two ports of the housing structure to launch or retrieve a pig ball therethrough. The valve ball is completely enclosed by the housing structure with a seal at the entrance to the magazine. The magazine has a bleeder valve to the atmosphere and also has a by-pass valve to equalize the fluid pressure in the magazine with the fluid pressure in the pipeline. The valve ball has compensating freedom to move towards and away from the seal. Manually operable gearing rotates the valve ball 90.degree. between its two alternate positions.

Abstract: A shut-off valve in a fluid line closes by spring pressure and/or line pressure and incorporates a control chamber wherein pressurized control fluid acting on a piston opens the valve in opposition to the spring pressure and/or line pressure. A 3-way actuator pilot normally places the control fluid in communication with the control cylinder but when vented cuts off the control supply fluid and releases the pressurized control fluid from the control chamber to cause the shut-off valve to close by spring pressure and/or line pressure. A monitor pilot responsive to pressure changes in the fluid line incorporates a relief valve and opens the relief valve by cam action to vent the actuator pilot whenever the pressure in the fluid line makes a predetermined departure from a normal pressure range.

Abstract: Reset means to advance a valve spool from a first valve seat to a second valve seat in opposition to exceedingly high biasing fluid pressure comprises a manually rotatable actuating means in screw threaded engagement with the body of the pilot valve. With the manually operable actuator at its retracted position, means is manually operated to operatively connect the manual actuator to the valve spool to permit advance of the manual actuator to drive the valve spool from the first valve seat to the second valve seat against the resistance of the biasing fluid pressure.

Abstract: Pressurized fluid is controlled by a reverse valve gate on a valve stem that extends through annular packing in a bore of a bonnet to a piston in an outer control chamber. Control fluid pressure moves the piston inward to open the valve against line pressure on the valve and/or spring pressure on the valve. In the absence of both line pressure and control pressure, the valve is closed by spring pressure. The control chamber construction permits quick replacement of control chamber seals. In the event of a fire, the control chamber seals disintegrate to release the control pressure and thus cause line pressure and/or spring pressure to close the valve. The valve stem packing may be conveniently expelled hydraulically for replacement. Various different control assemblies may be mounted interchangeably on the valve bonnet without disturbing the structure of the valve. An auxiliary control may be quickly mounted on the outer end of the control chamber to convert the shut-off valve to manual operation.