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Valtek MegaStream
Control Valves
GENERAL INSTRUCTIONS
The following instructions are designed to assist in the
disassembly, reassembly and troubleshooting of
MegaStreamTM attenuators in Valtek® valves. Product
users and maintenance personnel should thoroughly
review this bulletin in conjunction with Installation,
Operation, Maintenance Instructions 1 (Mark One and
Two Control Valves) before installing, operating or
performing any maintenance on the valve.
This publication does not contain information on installing, maintaining, troubleshooting, calibrating, and operating Valtek positioners. Refer to the appropriate Maintenance Instructions when this information is required.
To avoid possible injury to personnel or damage
to valve parts, WARNING and CAUTION notes
must be strictly adhered to. Modifying this product, substituting nonfactory parts, or inferior
parts, or using maintenance procedures other
than outlined could drastically affect performance and be hazardous to personnel and
equipment.
MegaStream attenuators are designed to reduce gaseous noise in automatic control valves through staged
pressure reduction and turbulence control. MegaStream valves have two basic designs: A one- or twostage attenuator for low to moderate pressure drop
services and a multi-stage attenuator for high pressure
drop applications. Pressure-balance designs are available in both types.
Installation
Standard unpacking and installation instructions are
outlined in Installation, Operation, Maintenance Instructions 1. Regardless of the air-action, it is imperative that valves equipped with MegaStream attenuators
be installed in the line with flow direction under the
plug. It is also strongly suggested that during startup, a strainer be placed in-line before valve to catch
debris prior to it reaching the MegaStream valve.
WARNING: Improper installation will result in excessive noise, causing possible damage to valve
parts or injury to personnel.
DISASSEMBLY AND REASSEMBLY
Disassembling Unbalanced MegaStream
Refer to Figure 1 and proceed as follows:
WARNING: Depressurize line to atmospheric pressure and drain all fluids before working on the
valve. Failure to do so can cause serious injury.
1. Fully retract plug until stem clamp is pointing to the
open position on the actuator stroke plate.
2. Remove bonnet flange bolting and lift actuator, bonnet and plug assembly out of the valve body. Remove the bonnet gasket.
WARNING: A hoist may be necessary for larger
actuators (size 50 and larger). Care must be
taken to lift the actuator and plug straight out of
the valve body. Any scraping of parts while
removing the actuator may damage valve parts.
When the actuator is not equipped with a lifting
ring, do not attach one; instead, lift the actuator
by using lifting straps through the yoke legs. In
this case, the center of gravity may be above the
lifting point. Therefore, support must be given to
prevent the actuator from rotating; otherwise,
serious injury may result.
3. With the actuator, bonnet and plug removed, the
attenuator can be lifted out of the valve body. In
larger sizes, the attenuator may be too heavy to lift
Valtek Part No. 10076401
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Bonnet
(Item No. 40)
Bonnet Flange Bolting
(Item No. 108/114)
Bonnet Gasket
(Item No. 58)
Body
(Item No. 1)
Seat Ring
(Item No. 20)
Bonnet Flange
(Item No. 70)
Attenuator
(Item No. 30)
Plug
(Item No. 50)
Seat Ring Gasket
(Item No. 55)
Figure 1: Unblanced MegaStream Assembly
NOTE: Item numbers correspond directly to valve's bill of material. Refer to it for specific part numbers.
without a hoist; in this case, tapped holes are machined into the top of the attenuator for installation of
lifting rings.
4. Remove the seat ring and seat ring gasket.
5. The attenuator may now be cleaned according to
established industry methods. If uncertain as to
which methods to use with a particular attenuator
and application, contact factory.
Reassembling Unbalanced MegaStream
Refer to Figure 1 and proceed as follows:
1. Install a new seat ring gasket and reinstall seat ring.
NOTE: Bonnet and seat ring gaskets should be
replaced each time the valve is disassembled.
2. Install the cleaned attenuator, making sure the hole
pattern closest to the edge is situated at the bottom
(by the seat ring).
3. Replace bonnet gasket.
4. Fully retract the plug (stem clamp indicator pointing
to the open position) and lower the actuator, bonnet
and plug squarely into the body and attenuator.
CAUTION: The bonnet aligns closely to the
body. Damage could result from misalignment
of the plug and attenuator; therefore, extreme
caution should be exercised in this operation to
make sure it is installed squarely.
5. Once the actuator is resting on the body, tighten the
bonnet flange bolting fingertight.
6. Seat the plug two or three times to center the seat
ring. This can be done by applying air to the actuator.
7. Leaving the plug in the extended (or closed) position,
begin tightening the bonnet flange bolting in a crisscross pattern that will keep the bonnet square with
the body. Tighten the first bolt 1/6 turn, then tighten
the bolt directly opposite 1/6 turn.
8. Continue tightening all bolts until the bonnet is firmly
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Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611
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Bonnet
(Item No. 40)
Sleeve Gasket
(Item No. 56)
Bonnet Gasket
(Item No. 58)
Body
(Item No. 1)
Seat Ring
(Item No. 20)
Bonnet Flange Bolting
(Item No. 108/114)
Bonnet Flange
(Item No. 70)
Sleeve
(Item No. 31)
Attenuator
(Item No. 30)
Plug Seals
(Item No. 65)
Plug
(Item No. 50)
Seat Ring Gasket
(Item No. 55)
Figure 2: Pressure-balanced MegaStream Assembly
NOTE: Item numbers correspond directly to valve's bill of material. Refer to it for specific part numbers.
seated, metal-to-metal, in the body. This can be
easily felt through the wrench.
9. Slowly stroke the plug up and down to check the
alignment of the plug with the attenuator.
Disassembling Pressure-balanced
MegaStream
Refer to Figure 2 and proceed as follows:
WARNING: Depressurize line to atmospheric pressure and drain all fluids before working on the
valve. Failure to do so can cause serious injury.
1. Fully retract plug until indicator is pointing to the
open position.
2. Remove bonnet flange bolting and lift the actuator,
bonnet and plug out of the valve body. A hoist may
be necessary for larger valves.
WARNING: A hoist may be necessary for larger
actuators (size 50 and larger). Care must be
taken to lift the actuator and plug straight out of
the valve body. Any scraping of parts while
removing the actuator may damage valve parts.
When the actuator is not equipped with a lifting
ring, do not attach one; instead, lift the actuator
by using lifting straps through the yoke legs. In
this case, the center of gravity may be above the
lifting point. Therefore, support must be given to
prevent the actuator from rotating; otherwise,
serious injury may result.
WARNING: Danger exists in removing the actuator, bonnet and plug–especially if Teflon pressure-balanced seals are used. The attenuator
sleeve may stick to the plug and fall during
disassembly, causing possible serious injury
and/or damage to the valve or nearby equipment.
Steps 3 thru 6 must be followed before attempting to remove the plug from the sleeve.
3. If the sleeve is observed sticking to the plug during
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6. Lift the actuator bonnet and plug assembly from
body, taking care not to damage the sleeve bore or
plug head.
7. Remove the sleeve attenuator, seat ring and gaskets
from the body.
8. The attenuator may now be cleaned according to
established industry methods. If uncertain as to
which methods to use with a particular attentuator
and application, refer to factory.
inches to allow the use of a ring compressor on the
metal rings. A suitable sized screw-type hose clamp
will also serve to compress the rings for reassembly.
Care should be taken to avoid damaging the sealing
surfaces while fitting the plug into the sleeve bore.
4. Once the bonnet is resting on the body, reinstall and
tighten the bonnet flange bolting fingertight.
5. Using the actuator, seat the plug two or three times
to center the seat ring.
Reassembling Pressure-balanced
MegaStream
Refer to Figure 2 and proceed as follows:
1. Install new seat gasket and reinstall seat ring.
NOTE: All gaskets should be replaced whenever
the valve is disassembled.
2. Install attenuator and sleeve. Replace bonnet and
sleeve gaskets, and plug seals.
3. Lower the actuator, bonnet and plug assembly
squarely into the sleeve bore. If Teflon seals are
used, the plug may remain retracted. With metal
piston ring seals, the plug must be extended a few
6. Leaving the plug in the extended (or closed) position, begin tightening the bonnet flange bolting in a
crisscross pattern that will keep the bonnet square
with the valve. Tighten the first bolt 1/6 turn, then
tighten the bolt directly opposite 1/6 turn.
7. Continue tightening all bolting until the bonnet is
firmly seated, metal to metal, in the body. This can
be easily felt through the wrench.
8. Slowly stroke the plug up and down to check the
alignment of the plug with the attenuator. If binding,
sticking or scraping noises are heard, stop stroking
valve immediately. Disassemble the valve to determine noise and to detect possible damage.
Troubleshooting MegaStream Control Valves
Problem Probable Cause Corrective Action
Jerky 1. Galling or scoring between 1. Superficial scoring or galling may be removed with a light application
stem travel plug and pressure-balanced of emery cloth; if more serious damage exists, contact factory
sleeve CAUTION: Trim parts are machined to close tolerances which are essential
2. Overtightened packing 2. Adjust the packing box nuts to slightly over finger-tight (over-tightening
3. Service temperature exceeds 3. Reconfirm service conditions and contact factory
operating parameter of trim design
4. Inadequate air supply 4. Check for leaks in air supply or instrument signal system; tighten any
5. Malfunctioning positioner 5. Refer to positioner maintenance instructions
Excessive 1. Insufficiently tightened 1. Refer to “Reassembly” section for correct tightening procedure
leakage bonnet flange bolting
2. Worn or damaged seat ring 2. Disassemble and replace or repair seat ring (for correct procedure on
3. Worn or damaged plug seals 3. Disassemble and replace plug seals
4. Worn or damaged gaskets 4. Disassemble and replace gaskets
5. Inadequate actuator thrust 5. Check for adequate air supply to the actuator; if supply is okay, reconfirm
6. Incorrectly adjusted plug 6. Refer to Maintenance Instructions 1 for correct plug adjustment
Restricted 1. Dirty attenuator 1. Disassemble and clean attenuator, using established industry
flow cleaning methods
2. Incorrectly adjusted limit- 2. Check stroke limiting device and correct, if necessary
stop or handwheel
Excessive 1. Improper flow direction 1. Check installation for flow direction under the seat; reinstall, if necessary
noise 2. Excessive pressure drop 2. Check design service conditions
3. Jerky or improper stemtravel 3. See corrective action under “Jerky stem travel”
4. Throttling too close to the seat 4. Recommended throttling should be 5 percent or more open
5. Loose parts 5. Check all external bolts and nuts for tightness; if noise is internal,
for correct functioning of the valve; attempting to remove deep scratches
could result in high leakage rates or improper functioning of valve.
will cause excessive packing wear and high stem friction)
loose connections and replace any leaky lines
remachining seat, see Maintenance Instructions 1)
service conditions and contact factory.
disassemble, check for damaged, scored parts or missing seat gasket
Flowserve and Valtek are registered trademarks of Flowserve Corporation.
FCD VLAIM018-05 ©1999 Flowserve Corporation. Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611
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