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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