Instruction Manual
D100399X012
EW Valve
July 2017
18
For the EWD carbon‐filled PTFE piston ring,
the ring is split in one place. If there is visible damage, spread the ring
slightly, and remove it from the groove in the valve plug. To install a carbon‐filled PTFE piston ring, spread the ring
apart slightly at the split, and install it over the stem and into the groove in the valve plug. The open side must face
along the stem, depending on flow direction, as shown in figure 22.
For each EWD graphite piston ring,
the ring can be easily removed since it is in two pieces. A new graphite piston ring is
furnished as a complete ring. Use a vise with smooth or taped jaws to break this replacement ring into halves. Place the
new ring in the vise so that the jaws will compress the ring into an oval. Slowly compress the ring until it snaps on both
sides. If one side snaps first, do not try to tear or cut the other side. Instead, keep compressing the ring until the other
side snaps. Be sure to match the broken ends when installing the ring in the valve plug groove.
For the EWT two‐piece seal ring,
the ring cannot be reused as it is a closed ring, which must be pried and/or cut from
the groove. Then the elastomeric backup ring (key 29) can be spread slightly and removed.
To install a new two‐piece seal ring, apply a general purpose silicone‐base lubricant to both the backup ring and seal
ring (keys 29 and 28). Place the backup ring over the stem (key 7) and into the groove. Place the seal ring over the top
edge of the valve plug (key 2) so that it enters the groove on one side of the valve plug. Slowly and gently stretch the
seal ring, and work it over the top edge of the valve plug. The PTFE material in the seal ring must be permitted time to
cold‐flow during the stretching procedure; so avoid jerking sharply on this ring. Stretching the seal ring over the valve
plug may make it seem unduly loose when in the groove, but it will contract to its original size after insertion into the
cage.
For the EWT spring‐loaded seal ring,
the ring used on a valve plug having a 136.5 mm (5.375 inch) or less port
diameter may be removed undamaged by first working the retaining ring (key 27) off with a screwdriver. Then
carefully slide the metal backup ring (key 29) and seal ring (key 28) off the valve plug (key 2). The spring‐loaded seal
ring used on a valve plug having a 178 mm (7‐inch) or greater port diameter must be carefully pried and/or cut from its
groove. Therefore, it cannot be reused.
A spring‐loaded seal ring must be installed so that its open side faces toward either the top or the bottom of the valve
plug, depending on flow direction, as shown in view A of figure 24. To install a spring‐loaded seal ring on a valve plug
with a 136.5 mm (5.375 inch) or less port diameter, slide the seal ring (key 28) onto the valve plug followed by the
metal backup ring (key 29). Then install the retaining ring (key 27) by inserting one end in the groove and, while
turning the plug, press the ring into the groove. Again, be careful not to scratch any surfaces of the ring or plug.
To install the seal ring on a valve plug with 178 mm (7‐inch) or greater port diameter, lubricate it with a general
purpose silicone‐base lubricant. Then gently stretch the seal ring, and work it over the top edge of the valve plug. The
PTFE material in the seal ring must be permitted time to cold‐flow during the stretching procedure; so avoid jerking
sharply on the ring. Stretching the seal ring over the valve plug may make it seem unduly loose when in the groove,
but it will contract to its original size after insertion into the cage.
CAUTION
Never reuse an old stem or adaptor with a new valve plug. Using an old stem or adaptor with a new plug requires drilling a
new pin hole in the stem (or adaptor in case an ENVIRO‐SEAL bellows seal bonnet is being used). This drilling weakens the
stem or adaptor and may cause failure in service. However, a used valve plug may be reused with a new stem or adaptor
except with Cavitrol III trim.
Note
The valve plug and valve plug stem for Cavitrol III trim are a matched set and must be ordered together. If the Cavitrol III valve plug
or valve plug stem is damaged, replace the entire assembly (key 2, figure 26 and 27).
2. To replace the valve stem (key 7), drive out the pin (key 8). Unscrew the valve plug from the stem or adaptor.
