Flowserve V-376 R4 Edward Valves - Manual (Page 6)

7
Flow Control Division
Edward V
alves
Disks In all Edward valves, disks are designed to swivel on the valve stem. They are held in place by either a “T”-slot connection, a disk nut, or Stellite wire.
T-slot Construction
Disk Nut Construction
Stellite W
ire Construction
Stop-Check valve disks are not attached to the stem and respond to the fluid flow in the same manner as check valve disks (see below). The disk seating face can be repaired in a similar manner to that described for seats.
Fig. 846
Typical Stop-Check V
alve with Body-Guided Disk
V
alve stems are nor
mally provided with a
radius at the disk contact to give center loading. If foreign material gets between this spherical sur
face and the disk, or if
galling occurs, it may not be possible to close the valve tightly
. In a leaking valve
this contact should be checked, if possible, to be sure it is in proper condition. Disk T
ack W
elds
In body-guided valve disks with disk nuts, the disk nut is secured to the disk by a small weld through the side of the disk, fusing the disk nut threads and preventing loosening of the disk assembly in ser
vice.
Such disks can easily be disassembled if required by drilling out the fused material
at the bottom of the small hole in the disk. The disk nut can then be unscrewed for ser
vicing. Care must be taken not to drill through the disk nut wall or the stem may be damaged. When repairs are complete, the par
ts can be reassembled with care
being taken to screw the disk nut down until only a few thousandths of an inch in end play remain in the assembly
. The par
ts
can then be lock-welded again by deposit- ing weld metal at the bottom of the small hole in the disk.
Fig. 838
Bolted Cover Piston Check
V
alves may be body-guided by rings on
the disk or in the case of “T”-slot disks by the disk outside diameter
. A similar body-
guiding arrangement may be found in check valves. Some ball check valves are guided by an extension of the cover (see Fig.
160). The wear on sliding sur
faces
inside valves should be considered and the sur
faces checked to be sure wear has not resulted in ridges in the guide bore, which might impair disk movement. Guiding in check valves is par
ticularly critical.
Disks and Disk T
ack W
elds
Disk
Nut
Construction
-
Bolted
Bonnet
Valves
-
Pre
1991
Disk
Nut
Construction
-
All
Univalves
and
Post
1991
Bolted
Bonnet
Valves