Flowserve Valtek MaxFlo 3 - Manual (Page 8)

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User instructions - MaxFlo 3 - VLENIM0052-02 02.07
8
8 SEAT REPLACEMENT
WARNING: The actuator must be removed from the valve
body prior to replacing the seat ring.
8. To replace the seat, see figures 4 and 5, and proceed as
follows:
8. Loosen the packing box nuts.
8.3 Using the appropriate retainer tool (see Table III), re-
move the seat retainer. (Retainer tools are available from
the factory).
8.4 Remove the seat and any shims that may be installed
under the seat.
8.5 Check both seat and plug surfaces for wear and galling.
Replace these parts if necessary.
8.6 Clean seat ring, seat retainer and body threads of old
sealant residue. Clean parts thoroughly.
8.7 To reinstall the seat, place the seat (without shims) into
the valve body. Rotate the plug to 90 degrees open.
Measure dimension “A” as shown in figure 4a.
8.8 Close the plug into the seat and then measure dimension
“B” as shown in figure 4b.
NOTE: For optimum sealing do not over-rotate the plug
into the seat. A very slight under-rotation is recommend-
ed. (See figure 5)
8.9 The difference between dimension “A” and “B” repre-
sents the total thickness of the adjustment shims to be
added between the seat and the valve body. See table III
to select the necessary shim(s). Regardless of the valve
size, at least one shim must be present.
8.0 Remove the seat and add the appropriate number of
shims. (Flowserve recommends a sealant with a tem-
perature range of –70 to 00 °C, type Dow Corning RTV
736, or a sealant with a graphite base for higher tem-
peratures or for steam processes.)
8. Apply lubricant to the threads of the seat retainer. Re-
place the seat retainer and tighten manually until it makes
contact with the seat, then loosen it by /8 of a turn.
Open and close the valve several times while tightening
the seat retainer manually to position the seat correctly.
Finally, close the valve and tighten the seat retainer ac-
cording to the values in table IV.
Figure 4: shimming the seat
Upon contact with the seat, the horizon-
tal axis of the plug must never be rotated
past the horizontal axis of the valve body.
The plug should rotate into the seat as
close to the horizontal axis as possible.
To increase this lag, reduce the thickness
of the shims, and vice-versa.
A
B
Parts supplied with the toolkit
for removing the seat retainer
Figure 4a: definition of dimen-
sion “A” with plug open
Figure 4b: definition of dimen-
sion “B” with plug closed
STOP!