Installation Instructions

Document No. 129-087
Installation Instructions
September 23, 2009
Page 2 of 4 Siemens Industry, Inc.
Installation, Continued
Figure 1.
3. Remove stem from stem extension in actuator
top. Then remove actuator from the bonnet.
4. For valve sizes 1/2-inch to 2-inches:
a. Loosen the bonnet from the valve body
using a 1-3/8 inch hex wrench for 1/2-inch
and 3/4-inch valves, and 1-5/8 inch hex for
1-inch through 2-inch valves. See Figure 2.
Figure 2.
b. Pull stem and disc assembly out of the
bonnet.
c. Hold disc holder firmly (in a vise if
possible). Then, using a 1/4-inch hex
wrench for 1/2-inch valve, 5/16-inch hex for
3/4-inch and 1-inch valves, and 1/2-inch
hex for 1-1/4 inch through 2-inch valves,
loosen the nut and remove it from the stem
to get access to the disc. See Figure 3.
Replace disc.
Figure 3. D.A. Assembly.
5. For valve sizes 2-1/2 inches through 6-inches:
a. Remove the four 3/4-inch hex cap screws
located on the top of the valve body and
remove the cap from the body. The gasket
between the top cap and the valve body
should be removed and replaced to assure
a tight seal when the valve is reassembled.
b. Pull stem and disc assembly out of the
bonnet.
c. A special throttling nut wrench is required to
loosen the throttling nut. This wrench can
be made as shown in Figure 7; it is not
available from the factory. Hold disc holder
firmly (in a vise if possible). Then, using the
special throttling nut wrench, loosen and
remove the throttling nut and disc. See
Figure 4. Assemble new disc and throttling
nut to stem. After tightening the throttling
nut, stake it (with a hammer, and punch in
four places) to stem assembly to prevent it
from becoming loose in service.
Figure 4.
6. Reassemble valve in reverse order.