Flowserve V-376 R4 Edward Valves Manual de usuario descargar pdf (Pagina 6)

7

Flow Control Division

Edward Valves

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 Wire 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 Valve with Body-Guided Disk

Valve stems are normally provided with a

radius at the disk contact to give center

loading. If foreign material gets between

this spherical surface 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 Tack Welds

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 service.

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

servicing. Care must be taken not to drill

through the disk nut wall or the stem may

be damaged. When repairs are complete,

the parts 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 parts

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

Valves 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 surfaces

inside valves should be considered and the

surfaces checked to be sure wear has not

resulted in ridges in the guide bore, which

might impair disk movement. Guiding in

check valves is particularly critical.

Disks and Disk Tack Welds

Disk Nut Construction - Bolted

Bonnet Valves - Pre 1991

Disk Nut Construction - All Univalves and

Post 1991 Bolted Bonnet Valves

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