Azbil VDC - Chapter 6: Parts Replacement; Replacement of Gland Packing

VDC, VAC, VST, VAA - Diaphragm Control Valve 6-1
Chapter 6 : Parts Replacement
6-1 : Replacement of Gland Packing
Before servicing the control valve, ensure to shut the ow in the process pipe, to
release pressure from inside the control valve, and wait until it cools o󰀨.
6-1-1 : Replacement of Yarn packing
Remove the actuator from the valve body. Disassemble the valve by following
the procedures explained in Chapter 4. “Disassembly and Reassembly,” Item (a)
Disassembly, Steps (1) through (4).
Undo the packing ange nuts. Remove the packing ange and packing follower. Use
the packing hook to remove a packing.
To remove packing lower than the lantern ring, unscrew the clamp nuts of bonnet,
remove the bonnet valve body, and then take out the lantern ring and packing.
Mount the bonnet on the valve body. Insert fresh packing, piece by piece, the cut
ends of piece shifted by 90 to 180 degrees of angle from that of the adjoining one.
Each time as you insert a piece of packing, securely press it with the packing
retainer.
Determine the number of pieces of Yarn Packing that is necessary so that the
lubrication hole is positioned lower than the lantern ring.
After inserting a su󰀩cient amount of the packing, place packing follower and the
packing ange, and secure packing ange nuts.
For the reassembly of a valve after packing replacement, follow the procedures in
chapter 5. “Disassembly and Reassembly,” Item (b) “Assembly,” from Step (5) and
further.
Replacement of V PTFE Packing.
Remove the actuator from the valve body. Disassemble the valve by following
the procedures explained in Chapter 4. “Disassembly and Reassembly,” Item (a)
Disassembly, Steps (1) through (4).
Unscrew the packing ange nuts. Remove the packing ange and packing follower,
and V packing holder use a packing hook to take out the V PTFE packing.
Insert fresh packing, with its V-shape groove positioned downward. (Insert this in
the reverse attitude for a control valve used for vacuum service.) Place the packing
follower and the packing ange, and secure packing ange nuts.
For reassembly of valve after packing replacement, follow the procedure explained
in Chapter 4. “Disassembly and Reassembly“, Item (b) “Assembly,” Steps (5) and
further.