5
Figure 9
springs
gland
spacer
pTFe Chevron packing
YarwaY
A.T.-Temp CryogeniC desuperheATer
InstallatIon and MaIntenance InstructIons
spray cylinder
once removed, inspect the condition of the
cylinder internally, using a flashlight. scratches
and blemishes may be removed by either
polishing or honing.
The cylinder bore should not exceed 32 mm
(model 37) with a maximum eccentricity
of 0.25 mm. debris can be removed from
the nozzles by blowing through with
compressed air.
inspect the nozzle atomizer outlet holes.
These should not show any undue elliptical
wear, roughness or damage or this will have a
detrimental effect on the A.T.-Temp Cryogenic
desuperheater performance. Carefully clean
the cylinder threading, dressing where
necessary, with a small file.
stem assembly
Withdraw the stem with piston. The piston
and stem are always supplied as a complete
assembly.
in case desuperheater is designed with piston
rings, replace as a matter of course, any time
that the unit is disassembled. Take care not to
overstress the piston rings when fitting. The
rings are marked ‘top’ and should always point
in the direction of the stuffing box, for proper
functioning.
if the piston (pFTe version) shows no signs of
wear and tear, then it may be re-used.
examine the condition of the stem, where it
runs in the stuffing box, remove any packing
material with a fine grade emery cloth,
polishing in the longitudinal direction.
stuffing box
remove all rings, springs and packing material
from the valve body. Clean the stuffing box
carefully, using a rotating wire brush and/or
honing device. Cleanless of the packing area is
vital for proper valve sealing. do not use grease
or lubricants in combination with pTFe Chevron
type packing! The actual packing design is
mentioned on the project related valve drawing.
only ever use genuine yarway components,
as they are supplied as matched sets
(see Figure 9).
disassembly (see figure 8)
The A.T.-Temp Cryogenic desuperheater can
be disassembled, most easily when in the
horizontal position with the body extension
section clamped firmly in the vice. grind off
the nozzle tack welds, using any standard type
of angle grinder. make sure that the weld is
removed sufficiently to allow rotation of the
fastener ring, without fouling.
unscrew the fastener ring by rotating
anticlockwise. note that the threading on the
body extension is right handed. Tapping the
fastener ring with a hammer may facilitate
removal. note that the threading on the
spray cylinder is left handed. if difficulties are
encountered with the removal of the fastener
ring, then this item may be removed by grinding
through at two diametrically opposite points.
please be careful not to damage the body
and spray cylinder threading.
Body extension
examine the threading on the body extension,
dressing where necessary, with a small
file. if care is exercised, during routine
maintenance, the valve body extension should
never require any repair work. if this threading
does become accidentally damaged, however,
then weld repair may be possible. it should be
noted that this job is for a specialist welder and
filler materials must be compatible with both
the base material and the service conditions.
in the event that such work is necessary, please
consult yarway or emerson for further advice.
