Flow Control, Flow Control April 2019

As pipeline gas travels from higherpressure pipelines to lower pressure pipelines in cities the gas passes through a gate station with worker and or monitor valves to reduce pressure The worker valve handles the pressure drop and maintains a lower pressure downstream This considerable pressure drop generates noise and vibration Typically noise attenuation trim is required along with features that provide tight throttling control The monitor acts as a backup to the worker if something happens it takes over and controls the pressure downstream While the monitor valve may require less throttling control it may still be needed to perform like a control valve An over pressure protection or super monitor valve often performs as a general service valve It can be upstream of the worker and monitor or at the inlet of a gate station or compressor station If the station needs to shut down this valve will close so throttling control and shutoff are important for this application A pump station pressure control valve minimizes the pressure drop when fully open These valves need to be able to handle transient conditions with higher pressure drops often occurring during startup that could lead to periods of cavitation Compressor stations may be placed every 50 to 100 miles on a pipeline to help boost pressure Typically an anti surge control valve is used to prevent the compressor from experiencing surge which can cause costly damage to the equipment Conclusion Proper ball valve selection will result in more uptime and better performance and it will prevent sucking out of seals and damage to the drive train The correct valve will provide appropriate control and reduce required valve maintenance Users should check published specifications to ensure the valve meets the aforementioned requirements The valve manufacturer should be able to provide technical assistance and demonstrate that the valve being considered has been used in similar pipeline applications FC Alex Schick is a product marketing manager for Fisher Rotary Valves at Emerson He is a graduate of the University of Iowa with a B S in Engineering and an MBA Schick has been with Emerson in Marshalltown Iowa for five years Joe DeMonte supports Emersons flow control products as the global midstream oil and gas and LNG industry manager He is also Emersons subject matter expert on anti surge valves DeMonte received a B S and M S in engineering from the University of Iowa www fl owcontrolnetwork com April 2019 19