Flowserve Cast Globe Valves - Manual (Page 31)

Globe Valves FCD ADENIM0011-00
31
7.0 ASSEMBLY (continued)
7.1.3 Yoke
1. Before installing the yoke, the stem clamp (029) should be lowered onto the stem. It should be left loose
until the yoke is in place.
2. Since access is better before the yoke is in place, it may be advantageous to install the packing at this
time.
3. The yoke (011) can now be lowered over the stem. Once it is properly positioned, the yoke capscrews
(217) can be installed and tightened.
4. The stem clamp can now be raised over the stem and the key; making sure the slotted end is captured
by the guide rib that is cast on inside of the yoke. When in place the set screw should be tightened and
staked.
7.2 Pressure Seal Bonnet Valves
7.2.1 Disc-Stem Assembly
The procedures for assembling the disc to the stem in a pressure seal valve is identical to the one for
flanged bonnet valves included in section 7.1.1. Refer to it for instructions.
7.2.2 Bonnet
Once the stem-disc assembly is in place the bonnet (002) can be inserted into the neck. Care must be
taken in lowering the bonnet on the stem, so that neither the backseat nor any surface of the stem is
damaged. It is again very important to keep the bonnet from cocking as it is lowered into the body. If it
does bind, the bonnet must be straightened before insertion can continue. Measuring the bonnet bolting
surface to the top of body is the simplest way to detect cocking.
With the bonnet sitting in the counterbore in the neck, a new gasket (032) can be inserted. In that the
gasket may also cock, it must be installed with care. Once these are in place, it is important to remember
that the piece with the drilled hole must be positioned last. If the valve is installed in other than the stem-
vertical position, it may be necessary to orient or hold the retainer such that the pieces stay in place until the
bonnet is moved into its raised position.
As previously mentioned, Flowserve uses one style of bonnet retention for globe valve 4” and smaller and a
different arrangement for globe valve 6” and larger.
On the smaller valves, the retainers (034) should be threaded onto the bonnet neck with the capscrews in
place but fully backed out of the ring. The ring should be threaded down on the bonnet until it starts to
tighten. Do not attempt to raise the bonnet by tightening the retainer. Do not thread the retainer so that it is
tight on the bonnet. Once the retainer is in position, it and the bonnet are raised into position by threading
the capscrews (216) through the retainer down against body neck. This will raise the bonnet and bring it
into contact with the gasket.
On larger valves, the bonnet retainer (034) can be lowered over the stem and placed in its position on top of
the body neck. The bonnet should be brought to the fully raised position and held (either by hand or a hoist
depending on the size) until the capscrews can be threaded into their holes in the bonnet. Note that
cocking must be avoided in raising the bonnet. If the bonnet binds before it is fully raised, it should be
checked for squareness. Note that while the capscrews need not be torqued to a specific value to maintain
a tight seal at system pressures, they should be tightened with wrench to insure good gasket-bodybonnet
seal contact before the full pressure is reached.