Flowserve Valtek Mark 200 - Manual (Page 8)

Mark 200 Control Valve FCD VLENIM0200– 12/12
8
6.2 Reassembling the Body
To reassemble the valve body, refer to Figure 3 or 4 then proceed as follows:
1. Install new bonnet and seat gaskets with the beveled edge up on
fluoropolymer gaskets.
NOTE: All gaskets should be replaced whenever the valve is
disassembled.
2. Relocate the seat ring. Carefully install the cage and then the sleeve
with the indexing feature provided, taking care to ensure they install
with the correct ends up.
3. Replace the plug seals on the plug, referring to Figure 5 and 6, and
observing the following directions:
WARNING: Gloves should be worn to help prevent the hands
from being pinched or burned.
PTFE Seals Heat one seal to 300°F (150°C) and slip it over the plug into the
seal groove. Thermal expansion causes the ring to stretch, thereby making it
relatively easy to slide over the plug head.
Care must be taken to prevent the seal from rolling, rather than sliding over
the plug. The second seal can be installed following the same procedures as
the first. If for any reason the second seal cannot be slipped onto the plug,
cut the seal at approximately a 30° angle (see Figure 6) and place over the
plug. Make certain the cut seal is on the low-pressure side.
Carbon Seals
Single Seals Each seal must be scored on a face with a sharp knife at
two places, 180 degrees apart. Holding the ring gently in a padded vise,
pull gently on the ring, breaking the ring on the score marks into two equal
pieces. Install the two pieces into the plug seal grooves with the score marks
on the pressure side.
Triple Seals Gently insert one end of seal and wrap the seal into groove.
Install the inside ring first, followed by the two outside rings with joints offset
120 degrees on all three rings (see Figure 5).
CAUTION: Install rings starting with one end and working the
ring carefully into place. Do not spread ring more than neces-
sary. Spreading the ring too much can cause the ring to break.
Metal Multi-Seals Install wave spring followed by four seal rings. Stagger
ring openings by at least 90 degrees. Take care not to bend the seal rings as
they are installed.
O-ring with Back-up Rings The O-ring can stretch over plug and into
place. Spread scarf cut back-up rings until they fit on each side of O-ring as
shown in Figure 5.
O-ring Seals
Carbon Single Seal Carbon Triple Seal
PTFE Seals Metal Multi-Seal
Figure 6 – PTFE Seal Cutting Detail
Figure 5 – Seal Designs