Flowserve Valtek Mark Six - Replacing the Soft Seat; Inspecting the Seat Ring; Reassembly of the Mark Six

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VLENIM0006-03 (AQ) July 2019
Figure 1: Soft seat plug head comparison
Item numbers correspond to the valve’s bill of material. Refer to it for specic part numbers.
Figure 2: Plug seal comparison
Spring-energized
liquid plug seal
Vented plug
Plug Head
Guide
Spring-Energized
Plug Seal
Replacing the soft seat
1. Disassembling the plug.
NOTE: Plugs with trim numbers to 1.5 in use a threaded plug head
design that clamps the soft insert between the plug head tip and plug
head. Disassemble the plug by removing the set screw and screwing
the plug head tip out of the plug head. A rod may be inserted into the
hole drilled through the plug head tip to facilitate removal.
Plugs with trim numbers above 1.62 in use a bolted design that clamps
the soft insert between the plug head tip and plug head. Disassemble
the plug by removing the cap screws.
2. Clean all parts.
3. Using a new elastomeric insert, reassemble soft seat compo nents
as shown.
NOTE: On small threaded plug heads, make sure the plug head
is screwed in tightly to compress the soft insert between the plug
head and the plug head tip. A set screw prevents the plug head
tip from working loose. Refer to Table 4 for the recommended
torque values.
Inspecting the screwed-in seat ring
1. Unscrew the seat ring using the correct seat ring assembly tools.
Assembly tools are available from Flowserve by refer encing Table 2.
NOTE: Flats are machined on the tool, so a wrench may be used to
turn the seat ring. Assembly tool supports are some times needed to
keep the assembly tool aligned properly in the seat ring. See Figure 4.
2. If necessary, remachine the seat surface. The seat angle on the
seat ring is 33 degrees from the vertical axis.
CAUTION: Ensure concentricity of seating surface with the
outside diameter of the seat ring.
3. Install seat ring using a seat ring assembly tool and tighten to the
appropriate torque value shown in Table 2.
Reassembly of the Mark Six
1. Install a new bonnet gasket.
2. Carefully lower plug as far as it will go into the body.
3. Slide the bonnet/actuator assembly over plug stem.
4. Insert guides and packing into the bonnet.
5. Place the gland ange onto the plug stem.
6. Screw the actuator stem onto the plug stem by rotating the
actuator in a clockwise direction.
Plug Head
(Item No. 50)
Set Screw
Soft Insert
(Item No. 21)
Self-Locking Insert
(Item No. 121)
Plug Head Tip
(Item No. 52)
Cap Screw
(Item No. 122)
Bolted plug pead (TN 1.62 and larger)
Threaded plug head (TN 1.50 and smaller)