AERCO SWDW68 U-Tube Double-Wall Heaters w/ECS - Manual (Page 62)

HE-
111 − CORRECTIVE MAINTENANCE
Rev B Mar 2013 8-8
CAUTION
In the following steps, avoid over-tightening the packing nut (18), which can trap the
Valve stem and slow or stop Valve motion.
10. Replace BOTH the packing nut (18) and the packing assembly (20) with a NEW packing nut and
packing assembly.
11. Replace the hex nuts (17) onto the Valve shaft (25) and position them in the same location noted in
step 7.
12. Attach the Actuator (27), linkage (26) and gasket (29) to the Valve top using the two cap screws (19)
provided.
13. Install the indicator plate on the Valve lower shaft (16) and secure it in place with the linkage adapter.
14. Reconnect the linkage adapter to the linkage shaft by replacing the shaft pin.
15. CriticaStepl: Autostroke the Valve and check for leaks.
8.2.2 Valve Disassembly
Refer to Figure 8-1 or Figure 8-2 and proceed as follows:
16. Close the upstream and downstream shutoff valves before and after the CXT-E Control Valve.
17. If the CXT-E Control Valve is easily accessible for disassembly and reassembly, leave it installed in
the Steam Input line. If it is not easily accessible, remove the Valve from the line and clamp it in a
bench vise for easy accessibility.
18. Completely remove the Actuator (27) and linkage assembly (26) from the Valve body, as described in
steps 1 through 5, above.
19. The following steps cover complete Valve disassembly, in the event it should ever be required. IT IS
STRONGLY RECOMMENDED, however, that the Valve be disassembled only to the extent
necessary to restore it to proper operation. When disassembling the Valve, USE EXTREME CARE
not to mar or scratch any surfaces.
The following steps assume that the Actuator and linkage assemblies have been removed from the
Valve body.
20. Remove the following Valve parts in the order specified:
CAUTION
CAREFULLY remove the packing nut (18) and cap screws (14) (listed below) to relieve
any trapped pressure.
a. Hex nuts (17)
b. Packing nut (18)
c. Packing assembly (20)
d. Cap screws (14)
e. Valve top (21)
f. Valve top gasket (13)
21. Grasp the lower shaft (16) and carefully remove the ENTIRE shaft/seat/piston assembly.
22. For 1-inch through 2-inch Control Valves (Figure 8-1), disassemble the shaft/seat/piston assembly in
the following order:
a. Lock washer (23)
b. Retaining ring (11)
c. Pilot spring (10)
d. Valve stem retaining nut (35)