Flowserve 51 Series - Manual (Page 3)

12230-N 3
2) With valve in closed position, remove end plug retaining
screws.
3) Remove end plug. If necessary, drive end plug from valve
using wooden drift applied to ball.
4) Remove body seal, ball, seats and seat back seals (if
any).
b. Removing Stem Assembly:
GENERAL NOTE: Due to different valve series and body styles,
one or two metal stem centering washers may be used and
the stem seal may be one-piece or three-piece.
1) Remove handle assembly (if any) by loosening handle
screw.
2) Remove retaining nut. Prevent stem from rotating by
holding stem with wrench.
3) Remove stop or valve stem spacer (actuated valves).
Remove and discard Belleville washer(s) (if any). Remove
and retain the follower.
4) Push stem into body cavity and remove. Remove stem
seal(s), stem seal protector (if any) and thrust bearing.
Remove and retain stem centering washer(s).
c. Visual Inspection:
1) The ball and the surfaces against which the seats and
seals are installed should be undamaged, clean and free
of pit marks and scratches. Light marring from the action
of the ball against the seats is normal and will not affect
the operation of the valve. Flaws which can be seen but
barely detected with finger tips are acceptable.
2) The stem and body surfaces that the thrust bearing and
stem seals contact, must be undamaged, clean and free
of pit marks and scratches.
d. Reassembly:
NOTE: Except for valves with graphite stem seals or V51
option, it is not necessary to replace Belleville washers.
CAUTION: Care must be used when handling graphite stem
seals, thrust bearing, body seals and seat back seals.
These parts can be easily damaged by squeezing the O.D.
of the seal. Parts are to be handled on the flat surfaces
rather than the O.D. These parts will not work if they are
cracked or broken. Light flaking of the material is
acceptable. If resistance is encountered when installing
stem seals over the stem, use follower to gently push the
stem seal down.
1) Lightly lubricate the ball, seats, seat back seals (if used),
body seal, stem seal(s), stem seal protector (if any) and
thrust bearing with a lubricant compatible with media
being handled, except for valves with V20, V33 or V38
options, which are assembled dry. White petroleum jelly
is a good general purpose lubricant.
For valve repair kits with “A” or “G” seats, the filled metal
seats will be lubricated at the factory. If they are not, they
should be lubricated as noted in Para. B.5 and also as
stated above. DO NOT operate a newly rebuilt valve using
filled metal seats without break-in lubricant. The seat back
seals will be pre-assembled to the seat backs.
For chlorine and oxygen prepared (prefix code “X”) valves
only, lightly lubricate the ball, seats, body seal, stem
seals, stem seal protector (if any), and thrust bearing with
a PTFE (fluoropolymer) lubricant, such as Fluorlube S-30
or equivalent.
2) To reassemble stem, reinstall stem centering washer(s)
into the recesses in the body. When only one washer is
used, it goes inside recess on top of the body and under
the stem seal(s). Place new thrust bearing onto stem and
insert through body cavity. The thrust bearing can be
distinguished from the stem seals by the darker color of
the 25% filled fluoropolymer used in the thrust bearing.
UHMWPE thrust bearings and stem seals are opaque
white in color and the same size, and are interchangeable.
Assemble new stem seal(s) over the top of the stem and
down into the recess in the top of the body. The follower
is installed on top of the stem seal(s). For valves with
graphite stem seal(s), the stem seal is metallic silver gray
and thicker than the thrust bearing. A Belleville washer is
also added, concave side up over follower (3” - 8” sizes
only). Place stop (or spacer) onto valve stem.
For valves with V51 high cycle stem packing option, the
thrust bearing and stem seals are the same size and color,
and they are interchangeable. A stem seal protector of
PEEK material and tan in color is also used and installed
over the stem seals.
NOTE: FOR ACTUATED VALVES HAVING A GRAPHITE
STEM SEAL OR V51 OPTION, TWO BELLEVILLE
WASHERS ARE USED. THE BELLEVILLES SHOULD BE
INSTALLED WITH THE LARGER DIAMETER SIDES
TOUCHING EACH OTHER. THE STEM SPACER IS
DELETED AND NOT USED.
ON ANTI-STATIC FIRE-RATED VALVES (AF51, AF52, FZ51
& FZ52) A BLACK, CARBON-FILLED FLUOROPOLYMER
THRUSTBEARING MUST BE USED FOR PROPER
GROUNDING OF STEM TO BODY.
3) When stem assembly is complete, place retaining nut
onto stem. Using handle or wrench to prevent rotation,
tighten retaining nut to fully compress packing or fully
flatten Belleville(s), if used, then backed off
1 /
6
turn.
Excessive tightening causes higher torque and shorter
stem seal life.
Flow Control Division
Worcester Controls