SOLDERING AND SILVER BRAZING
¡¡¡¡Analyze the application to determine
which valve is best suited for installations, keeping in mind
the service for which the valve is recommended. Before installing
the correct valve, review the installation instructions to prevent
damage to the valve and to assure its maximum efficiency.
1.Cut tube end square. Ream, burr and size.
2. Use sand cloth or steel wire brush to clean both ends to a
bright metal finish. Steel wool is notrecommended.
3. Apply flux to outside of tube and inside of solder cup. Surfaces
to be joined must be completely covered. Use flux sparingly.
4.Be sure that valve is fully open. Apply heat to tube first.
Transfer as much heat as possible through tube into valve. Avoid
prolonged heating of valve itself.
5.Silver Brazing Method: Assemble parts to be brazed. If fluxed
parts are allowed to stand, the water in the flux will evaporate,
and dried flux is liable to flake off, exposing metal surfaces
to oxidation. Assemble joint by inserting tube into socket hard
against the stop. The assembly should be firmly supported so that
it will remain in alignment during the brazing operation.
¡¡¡¡NOTE: On one-inch and larger valves,
it is difficult to bring the whole joint up to temperature at
one time. It will frequently be found desirable to use a double-tip
torch to maintain the proper temperature over the larger area.
A mild pre-heating of the whole socket area is recommended. Apply
heat to parts to be joined. The preferred method is by oxy-acetylene
flame. Heat tube first, beginning one inch from edge of valve.
Sweep flame around tube in short strokes up and down at right
angles to run of tube. To avoid burning through tube, the flame
should be in continuous motion and not allowed to remain on any
one point.
Apply flame to valve at base of socket. Heat uniformly, sweeping
flame from valve to tube until flux on valve becomes quiet. Avoid
excessive heating of valve.
¡¡¡¡When flux appears liquid and transparent
on both tube and valve, start sweeping flame back and forth along
axis of joint to maintain heat on parts to be joined, especially
toward base of valve socket.
6. Use just enough solder: with wire solder, use 3/4" for
a 3/4" valve, etc. If too much solder is used, it may flow
past tube stop and clog sealing area. When joint is filled, a
continuous run of solder or brazing alloy will be visible.
7. Silver Brazing Method: Apply brazing wire or rod at point
where tube enters valve socket. Keep flame away from rod or wire
as it is fed into the joint. Move flame back and forth as alloy
is drawn into joint. When the proper temperature is reached alloy
will flow readily into space between tube outer wall and valve
socket. When joint is filled, a continuous rim of brazing alloy
will be visible.
8. Remove excess solder with small brush while plastic, leaving
a fillet around end of valve as it cools.
SILVER BRAZING¡¡¡¡
¡¡¡¡The strength of a brazed joint does
not vary appreciably with the different brazing materials, but
depends to a large extent upon the maintenance of proper clearance
between the outside of the tube and the valve socket. The interior
dimensions of silver brazing valve sockets are machined to the
closest tolerances and finished smooth to promote full capillary
attraction.
¡¡¡¡NOTE: Care should be observed in cleaning
and in removing residues of the cleaning medium. Attempting to
braze a contaminated or improperly cleaned surface will result
in an unsatisfactory joint. Silver brazing alloys will not flow
over or bond to oxides. Oily or greasy surfaces repel fluxes,
leaving bare spots which oxidize and result in voids and inclusions.
THREADING
¡¡Grit, dirt or any foreign matter accumulated in
the pipe can hinder efficient valve operation and seriously damage
vital valve parts. Thoroughly clean pipe internally with air or
steam.
¡¡¡¡When threading pipe, gauge pipe threads
for size and length to avoid jamming pipe against seat and disc.
Thoroughly clean threaded end to remove any harmful steel or iron
deposits. For a good joint, use teflon tape or pipe dope. If pipe
dope is used, apply sparingly on pipe threads, neveron valve threads.
Do not allow any pipe dope into valve body in order to avoid damage
to disc and seat.
¡¡¡¡Before installation, check line of
flow through valve so that valve will function properly. Close
valve completely before installation. Apply wrench to hex next
to pipe and guard against possible distortion. After installation
of valve, support line; a sagging pipe line can distort valve
and cause failure.
FLANGED
¡¡¡¡There are several steps to follow
to make sure that a flanged joint will be properly assembled.
First, clean the joint carefully. Then loosely assemble the joint
by putting in the bottom two or three bolts. Then carefully insert
the gasket into place. The bottom bolts will help locate the gasket
and hold it in position. Then insert the rest of the bolts into
place and tighten all of the bolts evenly-not in rotation, but
by the cross-over method to load the bolts evenly and eliminate
concentrated stresses. The bolts should be checked for tightness
after an appropriate interval of use and retightened if nec .
All rights reserved by FBIC Inc., do remember to show the source
(www.fsbic.com) of the news when copying.
