4 | Baker Hughes
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CAUTION
CAUTION
WARNING
DANGER
Do not exceed supply pressure indicated on serial plate
located on the yoke of the actuator.
6. Body Disassembly
Access to the internal components of the body should be
accomplished with the actuator removed. To remove the actuator
from the body, refer to the actuator instruction Ref. 19530 for a
type 87/88 multispring actuator.
CAUTION
CAUTION
WARNING
DANGER
Prior to performing maintenance on the valve, isolate the
valve and vent the process pressure. Shut off the supply
air line and the pneumatic or electric signal line.
6.1 Threaded Trim (Figure 12 or 14)
After removing the actuator, disassemble the body using the
following procedure :
A.
If there is a leak detector connection on the lateral NPT port
of the bonnet, disconnect this piping as well.
B.
Remove body stud nuts (10).
C.
Remove bonnet (8), and plug stem (1) and plug (16) sub-
assembly together as one unit.
Note: Spiral wound body gaskets (11) are standard in
the 21000 Series design and it is imperative that a new
gasket be installed each time the valve is disassembled.
D.
Remove packing flange stud nuts (3), packing flange (4) and
packing follower (5).
E.
Remove plug (16) and plug stem (1) sub-assembly from the
bonnet (8).
CAUTION
CAUTION
WARNING
DANGER
Care must be taken to avoid damage to the plug and
plug guide.
F. Follow instructions for specific packing type in Section 7.6.1
A, 7.6.2 B or 7.6.3
G. Bonnet (8), plug (16), bushing (12) and seat ring (14) may
now be inspected for wear and service damage. After
determining the maintenance required, proceed to the
appropriate Section of this instruction manual.
6.2 Quick-Change Trim (Figure 13 or 15)
After removing the actuator, disassemble the body using the
following procedure:
A. If there is a leak detection connection on the lateral NPT port
of the bonnet, disconnect this piping as well.
B. Remove body stud nuts (10).
stop valve on each side of the 21000 Series valve with a manually
operated throttling valve mounted in the by-pass line (See Figure
2).
4.3 Flow Direction
The valve must be installed so that the process fluid will flow
through the valve in the direction indicated by the flow arrow
located on the body.
•
With contoured plug (21100/21600) or Lo-dB plug
(21700/21900)
flow-to-open
•
On anti-cavitation design (21700/21800) flow-to-close
4.4 Heat Insulation
For heat-insulated installation,
do not insulate the valve bonnet.
Take necessary protective measures relate to personal safety.
Welded Connections
CAUTION
CAUTION
WARNING
DANGER
Carefully review the information in this section prior to
welding any valves inline. Refer any additional ques-
tions to the local Baker Hughes Sales Office or Service
Center.
Pre-Weld Preparation
Carefully follow the installation steps defined in the sections
noted above prior to performing weld procedures.
Welding Process
Perform welding process in accordance with the standard
requirements for the materials and weld construction of the
specific valve. Apply post weld heat treatment if required.
CAUTION
CAUTION
WARNING
DANGER
Internal valve components should be removed prior
to performing welding or pre/post weld heat treatment
weld heat treatment in order to prevent damaging any
soft goods (such as PTFE seals). If unable to remove
the elastomeric components, then other methods must
be employed to prevent the local temperature around
the seals from exceeding the maximum material limits
(typically 450°F / 232°C for PTFE based materials).
Post Weld Cleaning & Assembly
Inspect the body, bonnet, and trim components for cleanliness
and surface condition. Remove any foreign materials, such as
weld chips, slag or scale. Make sure there are no nicks, scratches,
burrs or sharp corners on sealing and sliding surfaces. Clean all
gasket interface surfaces and reassemble using new gaskets to
ensure sealing integrity.
5. Air Piping
The actuators are designed to accept
1
/
4
" NPT air supply piping.
Use
1
/
4
" OD tubing (4 x 6 mm) or equivalent for all air lines. If the
supply
air line exceeds 25 feet in length (7 meters) or if the valve
is equipped with volume boosters, then
3
/
8
" tubing (6 x 8 mm) is
preferred. AII connections must be free of leaks.
