Flowserve Cast Globe Valves - Manual (Page 9)

Globe Valves FCD ADENIM0011-00
9
1.0 VALVE DESCRIPTION
(Continued)
1.3 Design Features (Continued)
1.3.3 Discs and Seat
Anchor/Darling Globe valves are supplied with a wide variety of discs to handle various throttling requirements. All
of the discs, however, are variations of three basic types (Fig. 6)
Quick Opening - for moderate throttling
Cage - for more severe throttling
Parabolic - for linear flow control
Anchor/Darling Globe valve discs incorporate a disc skirt to prevent cocking and to ensure proper disc/seat
alignment regardless of installation orientation. The globe valve main seat consists of a hard surfaced ring set into
a recess in the body which supports and retains it. A seal weld is provided between the body and the rings. This
weld is for sealing only and serves no structural purpose. The seat ring is replaceable.
There is a 1 degree difference in the angle on the disc and seat sealing surfaces (fig. 7). This design provides for
line contact at the seal and tight sealing at low force.
1.3.4 Valve Actuation
A globe valve is operated by moving the disc in and out of the seat with the stem. The necessary thrust for
opening or closing is imparted to the stem by the valve actuator which is supported and restrained by the yoke
structure. Five types of actuators are normally supplied: handwheel, manual gear, electric motor, pneumatic
cylinder and hydraulic cylinder. The first three impart rotary motion to a stem nut which converts the rotary motion
to linear stem movement via the ACME stem threads. The pneumatic and hydraulic cylinder actuators provide
direct linear motion to the stem.
Sealing of the bonnet stem penetration is accomplished by a bolted gland stuffing box containing ring-type
packing.
FIGURE 6 FIGURE 7