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Service Recommendations


Service Recommendations for Gate Valves


Gate valves are normally used for on-off service and are not recommended for throttling service.


Gate valves are normally installed in horizontal pipe runs with the stem vertical. They can also be installed in vertical or horizontal pipe runs with the stem other than vertical, but may require special construction depending on valve size, service conditions and materials. when purchasing valves for other than normal installation ,the valve orientation should be specified.


High Integrity Shutoff gate valves can be used for hot tapping or in pipeline services where a soft pig is used if the seat ring installation lugs are removed. Please specify.


Service Recommendations for Globe Valves


Globe valves are normally installed with flow and pressure under the disc. Always check with Pacific Valves before installing valves with flow in the other direction.


Under certain service conditions or when valves are equipped with cylinders or electric motor actuators, there may be a cost advantage in the designing and installing the valves with flow over the disc. If actuators are sized for these conditions, care must be taken to assure valves are installed correctly.


Threaded seat rings for valves in services with high velocity (turbulent) flow or thermal cycling should be lock welded to the body to avoid loosening. Please specify.


Conventional globe valves are suitable for most throttling applications and will provide the greatest service life where pipe line velocity in FT/SEC does not exceed 240. (v is a specific volume of flowing medium, ft.3/lb.) Prolonged throttling at less than 10% open is not recommended due to the possibility of excessive vibration, noise and damage to disc and seats. Use of smaller valves or V-Port trim with lower flow capacity may permit the valve to be open at a greater percentage, thus avoiding damage. Continuous severe throttling applications may require a control valve.


Service Recommendations and Limitations of Check Valves


Check valves are best suited for low to moderate velocity applications. Correct sizing of check valves is important. Either too low a line velocity or too high a velocity can damage valve internals and shorten valve life.


Service in systems involving frequent flow reversals and pulsation should be avoided. Check valves should be located as far away from equipment such as pumps and compressors as possible. Suspected problem systems should be reviewed with Pacific Valves Engineers before selecting and purchasing check valves.


Threaded seat rings for valves in services with high velocity (turbulent flow or thermal cycling should be lock welded to the body to avoid loosening. Please specify.


Limitations:


Globe pattern check valves should be used in horizontal pipe runs with the stem straight up.