Instruction manual

Instruction Manual
D500248X012
A31D Valve
April 2014
22
7. Place the flat side of the disk on a flat surface and insert wooden blocks to raise the disk approximately 50.8 mm (2
inches) from the worktable surface. Then, suspend the valve body over the disk so the seal/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 t o dislodge or damage the thrust bearings placed on the ends of the shafts.
8. With the disk (key 2) properly positioned in the valve body (key 1), 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, tangential 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. Beforeinstallingthetaperkey,besurethetaperkeydiskshaft joint is free of oil or grease. If necessary, remove any
excess welding material from the taper key.
11. Install the appropriate taper key and tangential pins.
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 following steps.
a. Drive the taper key in farther as follows:
VALVE SIZE, NPS MINIMUM DEPTH TO DRIVE TAPER KEY AFTER INITIAL SOLID CONTACT
NPS 8 CL300, NPS 10 and 12 CL150, & NPS 10 CL300 valves 6 mm (0.219 INCHES)
b. The disk shaft, and taper key assembly must be inspected to verify that the taper key spans t he entire shaft flat
width. If so, this procedure is complete. If not, the taper key must be driven in farther until this condition is
satisfied. However, do not exceed the following depth limits:
VALVE SIZE, NPS MAXIMUM ALLOWABLE DEPTH TO DRIVE TAPER KEY AFTER INITIAL SOLID CONTACT
NPS 8 CL300, and NPS 10 and 12 CL150 10 mm (0.375 INCHES)
NPS 10 CL300 11 mm (0.406 INCHES)
13. After driving the taper key in place, arc spot weld the head of the taper key to the disk as shown in figure 7. For NPS
10 and 12 valves, use an arc spot weld bead of 3/16-inch in diameter.
14. Refer to Packing Maintenance and the Anti-Blowout Design procedures in this manual to re-install the packing and
anti-blowout design.
Gasket Retainer
Valves with a two-piece shaft use a gasket retainer and gasket (keys 20 and 21) to cover the follower shaft opening in
the valve body. The gasket is held in place by the gasket retainer and four hex head bolts and lockwashers (keys 23 and
22). When reassembling the valve, use a new gasket.
Be sure to center the gasket over the follower shaft bore before retighteningbolts.Tightendownboltsevenlyina
crossoverorstarpattern.
Refer to table 6.
Installing the Gasket Retainer
All A31D valves use a gasket retainer and gasket to cover the follower shaft opening in the valve body.