Emerson A31A Manual de instrucciones descargar pdf (Pagina 8)

Cryogenic-Rotary Valve

Instruction Manual

Form 5482

February 2005

CAUTION

Never use a wrench or pliers on the

valve shaft. A damaged shaft could cut

the packing and allow leakage.

1. Before loosening any parts, isolate the valve from

the line pressure, release pressure from both sides

of the valve body, and drain the process media from

both sides of the valve.

2. Then, remove the hex nuts (key 18) and lift off

the packing follower (key 11). The packing (key 13)

is now accessible. Refer to figure 6 for details of the

blowout protection.

3. Use a packing extractor to remove the packing.

Insert the corkscrew-like end of the tool into the first

piece of packing and pull firmly to remove the

packing. Repeat this process until all packing has

been removed.

Note

For valves equipped with non-metallic

(PTFE composition) bearings, perform

the following step to inspect and/or

replace the outboard bearing (key 10).

4. Using a formed hook or probe, carefully remove

the packing ring (key 12) and inspect the outboard

bearing (key 10) for excessive intrusion or wear.

Outboard bearings are only found on the 3- through

12-inch sizes. If necessary, remove the bearing

carefully using needle-nose pliers and install a new

bearing and existing packing ring using the packing

follower (key 11) as a driver.

CAUTION

Be careful when cleaning the packing

box. Scratches to the shaft or inside

diameter of packing bore might cause

leakage.

5. Before installing new packing, clean the packing

box.

6. Install new packing (key 13) one ring at a time,

using the packing follower (key 11) as a driver. If

using split-ring packing, stagger the splits in the

rings to avoid creating a leak path.

7. Reinstall all parts. Tighten the packing follower

nuts (key 18) as needed to stop leakage under

operating conditions.

Removing the Valve from the Pipeline

1. Disconnect any operating lines providing air

pressure, electric power, or a control signal to the

actuator. Be sure the actuator cannot suddenly open

the valve. Vent the power actuator loading pressure.

2. Use bypass valves or completely shut off the

process to isolate the valve from process pressure.

Relieve process pressure on both sides of the valve.

Drain the process media from either side of the

valve.

CAUTION

Damage to the valve disc, piping or

pipe flanges can occur if the disc is

not closed when the valve is being

removed from the pipeline. If

necessary, stroke the actuator to place

the disc in the closed position while

removing the valve from the pipeline.

3. Loosen the flange bolting that holds the valve.

Make sure the valve cannot slip or twist while

loosening and removing the bolting.

4. Make certain the valve disc is closed and remove

the valve from the pipeline. Support the valve

properly and move the valve to an appropriate work

area.

Removing/Installing the Seal Ring

Unless otherwise indicated, key numbers and part

names are listed in figures 7 and 8.

Note

For valves large enough to be safely

placed on a flat surface without

tipping, it is possible to replace the

seal ring (key 7) while the actuator is

mounted to the valve and can be

accomplished by cycling the valve to

90 degrees open.

1. After removing the valve from the pipeline,

remove the manual or power actuator. Manually

rotate the drive shaft (key 4) counterclockwise until

the disc has moved a full 180 degrees away from the

closed position.

2. Lay the valve flat on a work bench in a secure

position with the retaining ring (key 2) and retaining

ring screws (key 19) facing up. Properly secure the

valve on a suitable worktable so it can not slip, twist,

or fall during maintenance. Remove all retaining ring

screws.

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 23 24

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Emerson A31A Manual de instrucciones Pagina 8

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