Baker Hughes Masoneilan 72000 Series Instruction Manual Download Page 13

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Masoneilan 72000 Series Control Valves Instruction Manual | 9

Model 722XX and 726XX (Polymeric Seal)

These valves are equipped with an inner elastomeric ring and an
outer PTFE ring.
1. Insert the elastomeric back-up ring (28) into the groove.
2. Place the PTFE seal ring (9) in boiling water for a few minutes.

Slide the seal ring along the plug until it slips into the groove.

3. For optimum insertion of the ring, a Serflex type ring

compressor can be used to compress the ring in the groove

for several minutes.

Model 729XX (Graphite Seal Ring)

These valves are also equipped with an inner and outer ring
arrangement. The inner metal ring has a straight cut and the outer

ring is made of graphite.
1. Replacement graphite seal rings (9) are supplied in a closed

ring form, and a notch must be cut before being assembled to

the plug.

2. Using a sharp blade, make a notch in the graphite ring. Hold

the ring on either side of the notch between the thumb and

index and bend until it breaks.

Using a very fine file, adjust each end of the ring so

that its external circumference corresponds to the internal

circumference of the cage (10) and (if applicable) the cage

retainer (11).

4. To adjust the length of the ring correctly, insert the new

graphite ring into the cage with the ring against the inner wall

of the cage (allowing for minimum play between the two ends

of the ring).

5. First assemble the inner metal ring into the cage groove, then

assemble the graphite ring over the metal ring. Be careful not

to damage the parts.

Note: The breaks on each ring should be placed approxi-

mately 180° apart.

Completing Valve Body Assembly

It is recommended to consult the factory for actual assembly cross

sectional drawing as some design configurations may vary from

the instructions.

Proceeds as follows:

After checking all sealing surfaces to ensure they are

thoroughly clean, assemble the seat ring gasket (26) in the

valve body (1). Make sure the gasket is centered properly in

the body.

2. Assemble the seat ring (13) into the valve body on top of the

seat ring gasket (26).

3. Install upper seat ring gasket (26) if applicable.

Note: For proper sealing it is important to confirm the gasket

is properly engaged in the seat ring gasket groove. If proper

alignment can not be achieved, spread a silicone grease,

such as Dow III, into the gasket groove to retain the gasket

during assembly.

Valve Plug and Cage Assembly

For 724XX (Auxiliary Pilot Plug) proceed to Step 6.

4. For valves using a straight plug design (See Figure 3),

install the cage (10) and (if applicable) the cage retainer
(11) into the valve body by seating it on top of the seat
ring. For valves using a bell shaped design (See Figure 2),

proceed to Step 7.

5. Insert the valve plug, stem assembly (7) including the seal

rings (9) and back-up rings (28) if applicable, into the valve

cage taking particular care not to damage the seal rings (9,

28) upon entry. Proceed to Step 8.

Note: Polymeric seal rings should be lightly greased with a

silicone based lubricant, such as Dow III, prior to installing

the plug into the cage.

Valve Plug and Auxiliary

Pilot Plug Assembly

6.  Assemble  either  the  flat  spring  washers  (sizes  3"  and  4")
or the coil springs (sizes 6" to 16"), then assemble the valve
plug  assembly  (8),  using  the  same  tools  as  those  used  for
disassembly  (see  section  on  disassembly).  Compress  the
springs so that the retaining ring (23) can be installed into the

groove in the main plug.

Note: For auxiliary pilot plugs with threaded spring

retainers, the retaining ring must be seal welded to the

main plug.

For trim configurations designed with a two piece cage

(cage and cage retainer):

7. Assemble the cage (10) into valve by seating it on top of the

seat ring (13).

8. If applicable, install body gasket (25) on to cage (10).
9. Assemble the cage retainer (11) over the valve plug

assembly (8) from the top of the plug stem. Make sure the

seal ring (9) in the plug groove stays positioned correctly.

Insert the cage and plug assembly into the valve body.