Type A31A
17
CAUTION
Premature valve failure and loss of pro-
cess control may result if bearings are
improperly installed or are damaged
during installation.
3. Using caution to prevent damage to the bearings,
insert the required number of journal bearings (key 7)
from the valve body bore into the drive shaft bearing
bore. When properly installed, one end of the journal
bearing(s) will be flush with the interior end of the
packing box, the other end of the journal bearing(s)
will be flush with the valve body bore.
The drive shaft thrust bearing (key 24) will be installed
in step 5.
4. Insert one journal bearing from the valve body bore
into the follower shaft bearing bore so it is flush with
the valve body bore.
5. Insert the drive shaft into the valve body through
the packing box. Push the drive shaft through the jour-
nal bearing. Hold the drive shaft thrust bearing (key
24) in the valve body bore against the opening of the
drive shaft bearing bore. Push the drive shaft through
the bearing bore just enough to hold the thrust bear-
ing.
6. Insert the follower shaft through the bore in the
valve body uncovered by removal of the gasket retain-
er. Hold the follower shaft thrust bearing (key 24) in
the valve body bore against the opening of the follower
shaft bearing bore. Push the follower shaft through the
bearing bore just enough to hold the thrust bearing.
7. Install the valve disk. Place the flat side of the disk
on a flat surface. Then, move the valve body from its
upright position and suspend the valve body over the
disk so the seal ring/T-slot area is facing up. Align the
shaft bores through the disk with the drive shaft and
follower shaft bores. Lower the valve body over the
disk using caution not to dislodge or damage the thrust
bearings placed on the ends of the shafts.
8. With the valve disk properly positioned in the valve
body, push the drive shaft and follower shaft the rest
of the way through the thrust bearings and into the
shaft bores in the valve disk.
9. Align the holes in the shafts with the holes in the
disk.
CAUTION
To avoid damage to the taper key, tan-
gential pins, disk pins, valve disk, or
shaft(s) resulting from the application of
excessive force, use appropriate care
when driving the key or pins into the
disk hub and shaft(s). Use the correct
tool, and do not use excessive force.
10. Before installing the taper key, be sure the taper
key disk shaft joint is free of oil or grease. If neces-
sary, remove any excess welding material from the
taper key.
11. Install the appropriate taper key, tangential pins,
and disk pins (see table 11).
12. Install the taper key by aligning the taper key hole
in the shaft with the holes in the shaft boss on the
disk. Insert the taper key. Use a pin punch to drive the
taper key until solid contact is felt. Measure the depth
of the taper key head for a reference during the follow-
ing steps.
a. Drive the taper key in farther as follows:
Valve Size, Inches
Minimum Depth to Drive Taper
key After Initial Solid Contact,
Inches (mm)
8-inch ANSI Class 300,
10- and 12-inch ANSI Class 150,
& 10-inch ANSI Class 300 valves
0.219 (6 mm)
b. The disk shaft, and taper key assembly must be
inspected to verify that the taper key spans the en-
tire shaft flat width. If so, this procedure is com-
plete. If not, the taper key must be driven in farther
until this condition is satisfied. However, do not ex-
ceed the following depth limits:
Valve Size, Inches
Minimum Allowable Depth to
Drive Taper key After Initial
Solid Contact, Inches (mm)
8-inch ANSI Class 300, and
10- and 12-inch ANSI Class 150
0.375 (10 mm)
10-inch ANSI Class 300
0.406 (11 mm)
13. After driving the taper key in place, arc spot weld
the head of the taper key to the disk as shown in fig-
ure 8. For valve sizes 10- and 12-inch, use an arc spot
weld bead of 3/16-inch in diameter. packing box.
Install the packing around the drive shaft.
14. Install the packing as described in the
Packing
Replacement section or in the ENVIRO-SEAL Packing
Instruction Manual (Form 5320).
Installing the Gasket Retainer
Valves with a two-piece shaft use a gasket retainer
and gasket to cover the follower shaft opening in the
valve body.
1. Replace the gasket (key 21) and gasket retainer
(key 20) over the end of the follower shaft. Use a new
gasket.
2. Replace the four hex head bolts (key 23) and lock-
washers (key 22) to hold the gasket retainer in place.
