Service Recommendations for Gate Valves
Date:2006-4-11 

1.Gate valves are normally used for on-off service and are not recommended for throttling service.
2.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.
3.Flexible or split wedges are recommended for service above 500oF to avoid wedge binding due to thermal expansion. This may occur if the valve is closed when cold, and then heated to operating temperature.
4.Threaded seat rings should be lock welded to the body when used in high velocity (turbulent) or thermal cycling services to avoid loosening. Please specify.
5.After closing a gate valve with sufficient force to develop shutoff, the stem should be backed off slightly (1/8 to 1/4 turn) to relieve stem load. This will enable the stem to expand slightly without binding or damaging the valve and will not affect shutoff.
6.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.






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