Flowserve Double-Disc Gate Valve Sizes 2.5 - Manual (Page 9)

9
Anchor/Darling Double Disc Type Gate Valves FCD ADENIM0003-01 - 07/14
flowserve.com
• Use unauthorized actuator assists such as – pipe
wrenches – cheaters.
• Bring valve to fully backseated position immediately
upon opening a valve in a hot system. Allow 15
minutes for stem to cool before backseating valve.
5.0 VALVE MAINTENANCE
Double Disc Gate valves are designed to be essentially maintenance free
pieces of equipment. When used in the proper application and operated
correctly, they will provide reliable operation for many years. The only
area that is expected to require regular attention is the adjustment
and (if necessary) replacement of the stem packing. The frequency
of this operation will be dependent on the service conditions, the type
of packing used and the care with which it is installed. Some other
maintenance recommendations are included in the following sections
for information.
5.1 Inspection
The most important aspect of valve maintenance is periodic inspection.
The early detection of a malfunction can, in many cases, prevent a
minor defect from becoming a major problem. It is very important that
leakage from any of the major seals (packing, disc/seat, body-bonnet)
be addressed immediately. The smallest weepage can quickly become
a major problem if it is not treated promptly. Some other areas that
should be included in a periodic inspection program are:
1. Lubrication:
• Stem
• Yoke Sleeve
• Motor Actuator Drive Sleeve
• Pneumatic Actuator Sliding Surfaces
2. Cleaning:
• Stem
• Packing Area
• Pressure Seal Area
• Body Bonnet Studs
3. Bolting:
• Body-Bonnet
• Bonnet Yoke
• Motor Actuator
• Yoke Clamp
• Mounting of accessories, (i.e. limit
switches)
5.2 Lubrication
1. Stem: Keep stem threads lubricated with a light coating of grease
such as Dow Corning Molykote P37 paste, Mobil grease 28 or MOV
Long Life.
2. Yoke Sleeve: Lubricate with general purpose grease every six
months. Apply with grease gun to grease fitting.
3. Air cylinder operated valves require only a light coating of grease or
oil on the Cylinder Rod.
4. Motor Actuator: Every six months lubricate drive sleeve top bearing,
using grease gun on pressure fitting in housing cover. See Motor
Actuator Manual for further information.
5. Bolting: Lubricate with Nuclear Grade Never Seeze or equal.
5.3 Cleaning
The frequency and extent of cleaning will depend on the valves’ location
and service conditions. It is important that the stem and packing gland
parts be kept clean and free of foreign material. Do not allow water
or dirt to collect in the body neck bore area above the pressure seal of
pressure seal valves. The build up of corrosion or extraneous material
may interfere with removal of the bonnet. For the same reason,
excessive rust should not be allowed to build-up on the body-bonnet
bolting of bolted bonnet valves.
5.4 Packing
6. Most Flowserve valves are supplied with graphite packing
supported by braided graphite end rings. Other packing materials
are furnished when specified.
7. Remove nuts from gland bolts and raise the gland flange and
gland. These two parts may be held out of the way with wire.
8. Clean the threads and insure the nuts thread on easily. Any
binding or sticking must be eliminated as this will adversely affect
torque values.
9. Remove the old packing with a packing hook. The lantern ring in
double packed valves must also be removed to expose the lower