CCI Severe Service Drag® Valves
The _______________ are located between the disk stack and the balance cylinder. It is important that when these springs are installed that the outside edges are touching and there is a space on the inside edges. The first or bottom ring should be placed concave side up and second spring should be opposite or concave side down.
* Belleville springs
The packing is either _________ or ___________ (what type) ??.
* Teflon or Graphite of the chevron type
The plug closes and mates to the seat ring to stop flow completely. The flow depends upon the position of the stem in the disk stack. The stem/plug assembly is connected to the _________________. Some plugs have piston rings that keep ______________.
* actuator stem by the stem clamp. * pressure from the balance cylinder.
Most valves have a ______________ to eliminate leakage around the plug.
* balance cylinder
It includes axial holes through the plug and a balance seal placed around the plug to ??
* balance the pressure above and below the plug. This pressure balancing significantly reduces the required actuator force.
Some valves have a one-piece ____________ and ____________; others have a collar __________________. The bonnet houses the stuffing box and the stem packing.
* bonnet and collar assembly * collar separate from the bonnet * stuffing box and the stem packing.
packing spacer is a smooth cylinder that is used to fill the stuffing box and give the packing a _________________. It has a chamfer or bevel on the end that goes________________.
* clean flat surface to rest on * into the stuffing box first.
Gasket Seal: Gasket seal bonnets obtain a seal by ?? The gasket is a spiral wound metallic/graphite type. This seal type is used primarily in ??
* compressing a gasket between the bonnet and body. * smaller control valve sizes and in high temperature service.
The CCI design uses a series of passageways in a ____________ that force the media to change directions several times, thus systematically ??
* disc stack trim * controlling pressure drops, reducing wear on valve internals: a simple but very effective design.
The ____________ permits changes in the flow rate while limiting the flow velocity through the valve.
* disk stack
The seat ring must be installed correctly. The outside taper must be installed ________________. This will position the seating portion of the ring up so it can mate to the plug. The seat ring has a ______________ on both the top and the bottom to provide the seal.
* down toward the bottom of the valve. * up * spiral wound gasket As with all spiral wound gaskets, once they have been used they must be replaced.
guide bushing: It guides the plug assembly through the disk stack. The guide bushing is designed to ________________. It is machined to fit into the ______________and _______________...
* fit correctly only one way in the valve * top of the disk stack (thicker raised face) and the bottom of the bonnet (thinner raised face).
Disk Stack cont... The position of the plug within the disk stack bore determines the _______________. The flow area expands in each passage. For ________, this keeps velocity constant as the specific volume increases. For___________, the velocity is reduced as the pressure is dropped to avoid ____________:
* flow by exposing more or fewer disk passages * gases * liquids * cavitation
The _______________ is between the bonnet and the disk stack.
* guide bushing
There is no way to tell exactly how much flow is actually going through the disk stack unless the valve is ___________. Just simply check that there is flow. If very little or no air is felt, then what is required?
* in service * chemical cleaning is then required.
The disk stack consists of a number of disks into which _______________ have been etched to allow a fixed rate flow capacity per passage.
* labyrinth flow passages
The CCI Drag® valve is designed to force the media through a disk stack. This disk stack has a number of disks containing small ______________. These passageways force the media to change direction many times through a tortuous path of right angle turns. The size and number of turns is ??
* labyrinth flow passages. * engineered to determine the amount of pressure reduction.
balance cylinder: It can either be a large metal cylinder or a small ring dependent upon the valve. Some valves may not have a balance cylinder if they have a _______________.
* large metal cylinder or a small ring dependent upon the valve * long extended bonnet.
Flow Direction: Over-the Plug: Over-the-Plug flow is typically specified for ___________________________. When the flow thru the control element is over-theplug, the flow enters the valve body, flows through the disk stack or cage, past the plug, and out through the seat ring bore.
* liquid flow applications, or for applications which require exceptional shutoff.
Pressure energized balance seals manufactured from materials such as Teflon are used in ______________. In higher temperature service, what type of seals are used??
* lower temperature service * graphite-based or metal piston ring type seals are used.
The positioner is used to signal the valve to ______________. It takes an electric input signal and coverts it to a _____________________.
* move the valve actuator. * pneumatic output to position the valve actuator to a desired point. It is important that the positioner is match marked before removal.
General Description of Operation: Severe service valves like the CCI Drag® valve generally operate ___________________. The media enters the valve either under or above the disc stack, changes direction, then exits the valve. This change of direction causes ___________________??
* on the same principle as a globe valve. * a pressure drop from the inlet to the outlet side of the valve.
The top and bottom rings of the Teflon packing both have what features?
* one flat side, which must be at the top and bottom of the stack.
__________ or ______________ should be used give surfaces a "polished" look.
Fine emery or crocus cloth
The pressurized seat plug assembly features a ???
pilot plug, a main plug, and a piston ring balance seal. The piston ring allows a small controlled leak of pressure from the valve inlet to the body cavity
The plug assembly includes: 2
plug and stem, or spindle.
The assembly extends or retracts the plug assembly within the body when ?
pressure is applied to either side of the actuator piston.
Apply slight force to the stem at various points until the packing follower drops freely into the stuffing box. This will identify which bolts need to be tightened. The direction in which the stem was pushed that allows the follower to drop indicates the ________________??
side of the bonnet that needs to be tightened.
This design does not feature balance holes, balance seals or pilot trim, and therefore may also be used in?
special cases where balance seal material is not compatible with the media. The unbalanced plug provides exceptional shutoff in the flow over-the-plug configuration.
Severe Service valves are designed to handle high pressure liquids and gases such as ? 4
steam, water, chemicals and petroleum products.
CCI (Control Components Inc.) Drag ® valves are a type of Pressure Reducing/Flow Control valve, designed to ??
step down the pressure in a system without damaging valve internals.
The ________________ is typically selected for very small plug sizes, when large actuator loading is not required to either lift or seat the plug.
unbalanced plug
The packing follower is used to compress the packing in the stuffing box just as in any other valve. However, it also has a secondary use: _______________________________. This can be accomplished by lifting the follower and allowing it to slide back down the stem shaft into the stuffing box. If it slides freely into the stuffing box, the bonnet is tightened evenly. If it does not slide freely, the bonnet is ??
when torquing the bonnet bolts, it can be used as a gauge to indicate that the bonnet is being tightened evenly. cocked and needs to be straightened.
The actuator assembly is bolted to the ??
yoke, and the yoke is clamped or bolted to the valve bonnet.
Severe Service valves are used in many applications throughout an energy center, including:
• Main and booster feedwater regulation • Start up and main feed pump recirculation • Deaerater level control • Condensate booster pump recirculation • Turbine bypass • Main steam and reheat steam de-superheat sprays
Cleaning: 6
• Parts should be immersed in suitable cleaning solvent. • Stubborn accumulations should be removed from surfaces with a non-metallic brush. Do not use abrasives to clean the plug stem or bore of the disk stack. • Remove all rust, scale, and any minor pitting of the interior body with fine grit emery cloth or a wire brush. • The disk stack should be soaked in solvent. Then compressed air should be blown through each disk passage in the reverse direction of the flow. • All parts should be dried with shop towels and compressed air. • Clean all gasket surfaces carefully as to not pit or scratch them. Do not use a wire brush on any gasket surface.
Inspection: Inspect all parts for wear and/or damage. 3
• Visually inspect all threaded parts and chase as necessary. • Inspect the actuator cylinder for damage. If the interior surface has been scored or is visibly worn it should be replaced. • Examine all finished surfaces for burrs, nicks or scratches. Slightly damaged surfaces should be smoothed with 400-grit crocus cloth. If they cannot be smoothed the part should be replaced.
Manual Override Assembly The top mounted manual override assembly is designed to allow ___________? The lower stem is connected with threads to the actuator stem. The upper stem is connected to the lower stem and thus moves with valve movement. The override is engaged by inserting a coupling into the slot on the upper stem. With the coupling in place the valve can be moved in either direction by turning the hand wheel.
* operation of the valve stem when control air is not available or when it is desirable to by-pass the controller to operate.
This transfers the mechanical force through the shaft to reposition the plug within the body assembly. In the event of a power failure, the _______________, which locks the piston.
* plug within the body assembly. *air is locked within the cylinder
When the control valve is closed and the pilot plug is seated, the pressurized seat plug assembly provides ___________.
* provides excellent shutoff.
As the stem continues to move in the opening direction, a shoulder on the stem engages a ??. The actuator needs only to supply what?
* retaining plate on the main plug, lifting the main plug off the main seat. * sufficient force to lift the balanced plug.
The_______________ is part of a pressure seal bonnet configuration. When pressure is applied to the bonnet bolt/studs, the seal ring seals between the bonnet and the valve body bore.
* seal ring * bonnet bolt/studs
The ____________ is located at the bottom of the valve and contains the actual valve seat. The plug mates with the seat ring to form the seal that stops the flow.
* seat ring
The bonnet assembly includes: 6 features
* seat ring * bonnet spacer * balance cylinder *bonnet * plug assembly * seals and packing.
When assembling, it is very important that all surfaces are __________________. The parts must fit together easily but tolerances must be ______________.
* smooth and clean * maintained
The ___________ connects the actuator stem to the valve stem/plug assembly. This is a split connector with a series of grooves machined into the opening to hold the stems in place. The _____________ is larger than the other grooves to allow the stems to touch when installed. When properly installed, ______________??
* stem clamp * center groove * the stems will touch inside the clamp.
When a signal to open the control valve is received, the actuator lifts the _______________. The pilot rapidly exhausts the bonnet cavity pressure,_______________.
* stem, opening the pilot seat. * balancing the plug assembly
The _____________ moves through the disk stack to allow regulation of the flow.
* stem/plug assembly
Metal seal bonnets obtain a seal by __________________? The system internal pressure applies a ____________________. (Figure 1, page 4). This seal type is primarily used on larger valves in low to medium temperature services.
* swaging a soft steel ring between the bonnet and body. * constant force on the seal face This seal type is primarily used on larger valves in low to medium temperature services.
Disk Stack cont... cavitation: definition?? The passages of each disk are designed to _______________. This allows the control element to operate at a pre-determined and controlled velocity over the full range of the designed capacity. This minimizes high velocities, which could result in what? 5 things
* the formation of partial vacuums in a liquid by a swiftly moving body, such as a propeller, causing pitting and erosion of surfaces as a result of these collapsing vacuums in the surrounding liquid * limit the flow velocity * noise, flashing, cavitation, vibration, and erosion.
* Belleville springs They are used to absorb what and do what? It is important that when these springs are installed that the __________________________. The first or bottom ring should be placed concave side up and second spring should be _______________.
* thermal growth and maintain tension as the valve parts heat and cool at different rates. * outside edges are touching and there is a space on the inside edges. * opposite or concave side down.
When servicing the disc stack, the airflow through the disc should be checked. To check the disk stack for flow, (do what)? _____________ and ___________________.
* use air pressure on the OD and place the hand on the ID to feel flow.
Disk Stack cont... Fluid resistance in the passages is developed by a series of right angle turns, with a specific number of turns in each passage to limit _____________. Since each disk has a known ___________, flow through the valve can be accurately measured and controlled.
* velocity to a pre-calculated level * known flow capacity
The shutoff pressure builds in the_____________________________, acting to close the valve. The actuator needs only to provide sufficient thrust to ??
*bonnet cavity above the plug *seat the pilot plug against the pilot seat in the main plug.
Valve Assembly: WHEN ASSEMBLING, MAKE SURE THAT ALL PARTS SPIN FREELY IN THEIR LOCATIONS. 17 steps. Listing 1 - 3 on this card.
1. Apply lubricant (Dow Corning 111) to the lower spiral wound gasket that goes on the bottom of the seat ring. The bottom of the seat ring has the large taper on the outside and the top has the smaller taper on the inside for the plug to seat. 2. Place the seat ring in the valve and rotate it several times to ensure proper seating in the body recess. 3. Place the upper spiral wound gasket in the groove on the top of the seat ring.
Actuator Assembly: 9 steps.... listed 1 - 7 with a caution note:
1. Apply lubricant to all O-rings and install them. 2. Apply a light coat of o-ring lubricant to the interior surface of the cylinder. 3. Install the cylinder onto the lower cap. 4. Secure the actuator shaft in a vise equipped with soft jaws. NOTE: The shaft should be held by the milled flats. If the shaft does not have milled flats, install the stem clamp on the shaft and clamp the stem clamp in the vise. 5. Secure the piston to the actuator shaft. NOTE: Apply thread locker to the actuator shaft threads before installing the extension shaft. 6. Insert the actuator shaft into the lower assembly. 7. Slide the upper cap onto the extension studs. Be sure to position the ports for correct alignment. CAUTION: be sure the upper cap is seated properly on the cylinder or leakage will occur.
Disassembly Procedure: 18 Steps... I broke them down. This notecard list the first 4.
1. Ensure that all WPA is correct and in place. 2. Disconnect the positioner and air supply. 3. Bleed off any air that may remain in the cylinder with the bypass valve or by opening an air line. 4. If the valve has a manual override it must be engaged at this time to close the valve. To engage the manual override:
Double Acting Actuator Disassembly: This type of actuator does not have springs and can be disassembled as any other double acting pneumatic cylinder. List 6 steps:
1. Ensure that there is no pressure in the cylinder. 2. Loosen and remove the nuts on the upper cap. 3. Remove the upper cap. 4. Tilt the cylinder at the top to break sealing tension at the lower cap and remove the cylinder. 5. Slide the actuator shaft and piston from the lower cap. 6. Place the actuator shaft in a vise with soft jaws and remove the extension shaft. Secure the shaft by the milled flats on either side. If the shaft does not have milled flats, attach the stem clamp to the shaft to hold the stem in the vise.
Packing Replacement, Graphite: 11 steps.... only listing 1-7 on this slide.
1. Isolate valve form all line pressure 2. Release the pressure form the valve. 3. Close the valve. 4. Remove the stem clamps. 5. Stroke the actuator stem up, away from the valve stem. 6. Remove the packing flange and packing follower. 7. Remove all packing with packing removal tool.
Packing Replacement, Teflon: 11 steps.. listing 1-7 on this slide.
1. Isolate valve from all line pressure. 2. Release the pressure from the valve. 3. Close the valve. 4. Remove the stem clamps. 5. Stroke the actuator stem up, away from the valve stem. 6. Remove the packing flange and packing follower. 7. Remove all packing with packing removal tool.
Bonnet Seal Design: The bonnet seal may be one of two types:
1. Metal seal 2. Gasket seal
The flow thru a CCI Drag® valve can be configured in two ways:
1. Over-the-Plug / Flow-to-Close 2. Under-the-Plug / Flow-to-Open The valve flow direction is indicated by a tag on the valve body.
Procedure for disassembly of spring loaded "fail closed" actuator. Steps 1 - 4 with caution note. Important safety note: Take steps to ensure a controlled release of spring energy
1. Remove three equally spaced studs and nuts from the upper cap. 2. Replace the three removed studs with three all thread studs that are approximately 75% longer than the cylinder. Allow the excess length of the studs to extend above the upper cap. Install two nuts for each stud on the lower end cap and one on the upper end cap. 3. Remove the three remaining studs. 4. Alternately back off the nuts on the extension studs until the spring tension is released. Caution: If the nuts are not removed evenly, the end cap could hang up in the threads. If the end cap breaks free it could cause injury. Caution: If the nuts are not removed evenly, the end cap could hang up in the threads. If the end cap breaks free it could cause injury.
Plug Assembly Design: CCI Drag® valves have one of three basic plug assembly configurations designed to best suit the application:
1. Unbalanced Plug Assembly 2. Balanced Plug Assembly 3. Pressurized Seat Plug Assembly
Design Features: A typical CCI control valve will include five major elements:
1. Valve Body 2. Disk Stack 3. Bonnet Assembly 4. Plug Assembly 5. Actuator and Controls Assembly
steps 10 - 12
10.Install the bonnet washers and nuts on the bonnet studs. Lubricate the washers on both sides, the threads of the studs, and the bottom of the nuts. This will ensure that when tightening the torque that is applied is true. 11.Torque each of the nuts with a Hytorc wrench to the specified torque. The nuts need to be torqued using a cross circular pattern in increments as listed in the torque charts. The packing follower should be used as a gage to indicate when the bonnet is being tightened evenly. Lifting the follower and allowing it to slide back down the stem shaft into the stuffing box does this. If it slides freely into the stuffing box, the bonnet is tightened evenly. If it does not slide freely, the bonnet is cocked and needs to be straightened. Pushing on the stem at various points until the packing follower drops into the stuffing box does this. The direction in which the stem was pushed that allowed the stem to drop indicates the side of the bonnet that needs to be tightened. 12.Install the packing. Either Teflon or graphite packing is used on these valves. Follow the procedure described earlier when packing the valve. MAKE SURE THE PACKING SPACER IS INSTALLED PROIR TO THE PACKING.
step 8: list step 8 and the 2 details that do with it.
8. Install the packing. A. Install the packing spacer and make sure that it is seated at the bottom of the stuffing box. B. Install the specified number of packing rings. The set is chevron type packing with a bottom ring that is flat on the bottom and convex on the top. The top ring is flat on the top and concave on the bottom. All the rings in between are convex on the top and concave on the bottom.
steps 13 - 18
13.Remove the gasket seal from the body. If the bonnet is a pressure seal type it will have a seal ring instead of a gasket. Lift the seal ring off of the bonnet. 14.If the packing and spacer was not removed earlier, use a packing hook to remove the packing from the top or push the packing and spacer from the bottom with a brass bar carefully as to not damage the spacer. 15.Using the stem clamp and the yoke clamp remove the stem and plug assembly. Dependent upon valve design, the stem and plug may be a cartridge assembly. The cartridge assembly contains the balance cylinder, Belleville springs, guide bushing, disk stack, and seat ring as a unit. The balance cylinder and seat ring is attached to the disk stack with set screws that will need to be removed. The Belleville washers are located between the disk stack and the balance cylinder. Do not disassemble the stem and plug assembly unless so instructed. 16.After the stem and plug assembly is removed from the body, remove the guide bushing; balance seal/cylinder and any spacers from the bonnet. Some valves may have Belleville washers here that will need to be removed. 17.Lift the disk stack from the valve. Larger disk stacks usually have threaded holes in the top for lifting. Use eyebolts or a lifting tool to remove disk stack. 18.Carefully remove the seat ring. The seat ring will have spiral wound gaskets on the top and bottom. Remove and discard them.
steps 13- 15
13.Rig the actuator assembly and lower it onto the bonnet. Be sure that the stem is in the up position. It should already be in this position from the disassembly. If it is not, apply air to the bottom port of the cylinder until it retracts upward. 14.Attach the yoke clamp to the bonnet and actuator and tighten. 15.Apply air to the top port of the cylinder to move the cylinder stem down until it touches the valve stem. This will push the valve stem down on its seat. It is very important that these two stems remain touching when the stem clamp is attached.
steps 16- 17
16.Install the stem clamp to the valve stem and actuator stem. Be sure that any accessory hardware for the positioner and limit switches are in place. NOTE: Torque the stem clamp bolts evenly in a cross pattern to keep an equal gap on both sides. 17.Connect the air supply lines.
listing steps 4 - 6
4. Lower the disk stack into the body until it is seated. The disk stack should be installed with the end that has fewer holes to the bottom. Rotate the disk stack several times to ensure it is seated properly. NOTE: Larger disc stacks have threaded hole in the top for lifting with eyebolts and sling or some other lifting device. 5. Install the stem/plug assembly. Apply lubricant the plug to aid in smooth insertion. NOTE: Larger plug/stem assemblies may need to have rigging for installation. If rigging is needed, the yoke clamp and stem clamp may be used to lift the plug assembly with slings. Rotate the stem/plug assembly several times to ensure it is seated properly. 6. Place the guide bushing on top the disk stack. Make sure that it installed properly. The larger ring should be on the bottom and the smaller ring should be on the top. Rotate the guide bushing several times to ensure it is seated properly.
Procedure for disassembly of spring loaded "fail closed" actuator. 5 - 8
5. Remove the upper cap and springs. 6. Tilt the cylinder at the top to relieve the sealing tension at the lower cap and remove the cylinder. 7. Slide the actuator shaft and piston from the lower cap. Note: If the actuator is equipped with a manual over ride, an extension shaft connects the piston to the actuator shaft. 8. Place the actuator shaft in a vise with soft jaws and remove the extension shaft. Secure the shaft by the milled flats on either side. If the shaft does not have milled flats, attach the stem clamp to the shaft to hold the stem in the vise.
Steps 6 - 12
6. Attach slings to the actuator with screw eyes. 7. Remove the stem clamp and positioner linkage. Be sure to match mark for proper position when installing. 8. Remove the packing flange and yoke clamp and lift the actuator assembly off the valve body. 9. Loosen the bonnet nuts with a Hytorc wrench and remove the nuts and washers. 10.Remove the packing follower, the packing and the packing spacer. Note: The packing and spacer may be left in at this time and removed after the bonnet is out of the valve. 11.Attach the yoke clamp to the top of the bonnet and slings to the clamp. If the bonnet is a two piece type (ring & bonnet), attach eyelets to the bonnet ring and lift. 12.Carefully lift the bonnet assembly from the valve body.
Steps 7 - 9
7. Some valves may have Belleville springs that are located on top of the disk stack. It is very important that they be installed properly. They should be installed with the outside edges touching and a space between the inside edges. (First spring concave side up; second spring concave side down). Rotate the springs several times to insure that they are seated properly. 8. Install the balance seal. Lubricate the inside of the valve balance seal bore and outside of the balance seal with Dow Corning 111. There are several different configurations of balance seals. One type is a Teflon ring that is inserted into the bottom of the bonnet assembly. Another style is either a small or large metal ring. Smaller rings usually have a spacer above and below the seal. Rotate the balance seal and/or spacers several times to ensure it is seated properly. 9. Install the bonnet. Lubricate the inside of the valve bonnet bore and the outside of the bonnet with Dow Corning 111. Rig the bonnet and carefully lower over the stem/plug assembly.
list 8 - 9 step 9 has 5 details that go along with it. List them.
8. Install the studs and tighten the nuts until the end caps are seated against the cylinder. 9. Install the manual override assembly if so equipped. A. Lower the assembly over the upper stem with care as to not damage the stem. B. Reinstall the bolts and torque to 80 ft /lbs. Be careful to not over torque. C. Operate the assembly to ensure correct operation. D. Be sure that the manual override assembly is disengaged from the actuator assembly. E. Place the actuator bypass valve in the proper position for operation.
Step 8 listed: list step 8 and the 7 details along with it.
8. Replace the packing. A. Be sure that the packing spacer is installed and fully seated in the bonnet. B. Lubricate each packing ring (laminated graphite ring and lattice braided filament graphite ring) with a thin coat of Never-seez. C. Place a braided ring and a laminated ring into the stuffing box. D. Install the packing follower, the packing flange, and the eye bolt nuts. E. Tighten the eye bolt nuts and torque to the specified torque. F. Remove the eyebolt nuts, the packing flange, and the packing follower. G. Install the remaining laminated rings and the top braided ring and then repeat the tightening sequence.
steps 9 - 11
9. Slide the packing follower over the spindle and push the packing rings down into the valve stuffing box. 10.Assemble the yoke clamp to the bonnet and slide the packing flange onto the spindle. 11.Tighten the packing flange nuts evenly to the specified torque
steps 9-11
9. Slide the packing follower over the spindle and push the packing rings down into the valve. 10.Assemble the yoke clamp to the bonnet and slide the packing flange onto the spindle. 11.Tighten the packing flange nuts evenly to the specified torque
Step #5. The manual over ride must now be disengaged to remove the actuator from the valve. To disengage the manual override:
A. If the valve is a Fail open type, rotate the hand wheel back and forth until no tension is felt on the hand wheel. Turn the actuator by-pass valve to the closed position. B. If the valve is a Fail close or fail in place type, move the valve to the normal position (springs extended). Rotate the hand wheel back and forth until no tension is felt on the hand wheel. Remove the coupling and rotate the hand wheel to return the screw shaft to the extended up position. Adequately thread the coupling into the hole on the top. Place the by-pass valve on the actuator in the closed position.
This card explains #4 in detail. If the valve has a manual override it must be engaged at this time to close the valve. To engage the manual override: 4 points
A. Vent all air from the cylinder, allowing the springs to relax. Be sure to loosen a fitting to ensure that there is no air trapped in the cylinder. B. Turn the actuator by-pass valve to the open position. C. If the valve is a fail open type, leave the upper cap threaded in and rotate the hand wheel to close the valve. D. If the valve is a fail close or fail in place type, unscrew the coupling to expose the top of the upper stem. Rotate the hand wheel until the top of the upper stem is exposed enough to engage the coupling. Completely insert the fork of the coupling into the groove to secure the positive movement in either direction.
Actuator Assembly: The actuator assembly is a pneumatic cylinder mounted to the valve body assembly with the yoke, _______________?
and connected to the plug stem with an actuator shaft and stem clamp.
The _______________ is located on the bottom of the bonnet assembly.
balance seal
The ___________________ is used to reduce actuator loading and is the most commonly used plug assembly configuration.
balanced plug design
the override is engaged by inserting a coupling into the slot on the upper stem. With the coupling in place the valve can be moved in either direction by turning the hand wheel.
be moved in either direction by turning the hand wheel.
balance seal: It provides the seal between the bonnet and the balance cylinder. It is usually a Teflon seal with spiral wire inside.
bonnet and the balance cylinder. It is usually a Teflon seal with spiral wire inside.
The graphite packing has what features?
braided rings at the top and bottom with laminated rings in-between.
They are highly engineered to eliminate the problems of ?? 4
cavitation, noise, erosion, and vibration.
The packing follower is used to ??
compress the packing in the stuffing box just as in any other valve.
CCI drag: The position of the stem and plug in the disk stack _______________
controls the amount of flow.
When the flow thru the control element is over-theplug, the flow enters____________??
enters the valve body, flows through the disk stack or cage, past the plug, and out through the seat ring bore.
Some actuators are spring loaded. In the event of a power failure, the springs and/or air tank, when supplied with air will?
force the plug to the specified failure position.
The Pressurized Seat Plug Assembly is used in ??
high temperature service requiring tight control valve sealing.
Air to position the actuator shaft within the cylinder is received at the ? This transfers the mechanical force through the shaft to reposition the plug within the body assembly. In the event of a power failure, the air is locked within the cylinder, which locks the piston. Some actuators are spring loaded. In the event of a power failure, the springs and/or air tank, when supplied will force the plug to the specified failure position.
inlet port, forcing the actuator shaft to move in the appropriate direction.
The pressurized seat plug assembly provides the shutoff of an unbalanced plug with the ??
low actuator force requirements of a balanced plug.
The lower stem is connected with threads to the actuator stem. The upper stem is connected to the ___________________?
lower stem and thus moves with valve movement.
The ________________ is located at the bottom of the stuffing box. It is a smooth cylinder that is used to fill the stuffing box and give the packing a clean flat surface to rest on. It has a chamfer or bevel on the end that goes into the stuffing box first.
packing spacer
