Flowserve V-378 R1 Edward Equiwedge Gate Valve - Manual (Page 9)

9
Flow Control Division
Edward Valves
VALVE BODY REPAIRS
Body Bore Gasket Seal Area Repair
(Valves with metal gasket only)
Class 600 Equiwedge gate valves have
the seal area for the pressure seal just
below the top of the body bore. The seal
surface is inlaid with 18-8 stainless steel
on all valves size 16 and larger.
Class 900 and higher Equiwedge gate
valves have the seal area just below the
gasket retainer groove. The seal surface is
inlaid with 18-8 stainless steel on all valves
in these pressure classes.
The seal area, whether inlaid or not, must
be smooth, round and without any appre-
ciable taper. Upon normal disassembly of
the valve the gasket may leave some verti-
cal score marks when withdrawn.
If the depth of defects are .010” or less,
the seal area can be honed using a
portable Sunnen Hone. This device is
adjustable for different bore sizes and can
be operated by one man using a portable
electric drill of 1/2” to 3/4” capacity.
When the defects are greater than .010”,
welding will be required to cut down the
repair time.
First make visual inspection all around this
area, noting, if possible, where flaws may
occur. Next wash the area with a suitable
solvent, drying with clean rags and, if nec-
essary, polishing with a fine grade of
emery cloth to remove any undesirable
scale or foreign matter which may be been
deposited on the area suspected of having
flaws. Use a dye penetrant test if cracks
are suspected.
Where it is necessary to repair the body
inlay by welding, note the following:
1. Prior to any cutting or welding oper-
ations being performed on the valve,
it is necessary that adequate seat
joint protection be provided and
some means of insurance against
getting chips, weld spatter or other
foreign matter into the pipe line if
the valve is permanently mounted. A
round piece of sheet metal placed in
the bore down to the shoulder above
the guide grooves and taped in
place will protect the guide surfaces
and seats.
2. Chip out the defective area in the
body, being careful to remove the
affected portion to its end, inside the
casting, and to thoroughly clean it
away.
3. With a small hand grinder, grind the
chipped area smooth.
4. Preheat an area large enough
around the imperfection so that dur-
ing the entire welding operation heat
will be retained at approximately
400 degrees Fahrenheit.
5. Use a stainless steel inlay selected
from either 18-8 stainless steel rod,
Harstain 18-8, Stainweld “K” 18-3,
Stainweld 18-8 or equivalent.
6. Lay the weld in thin, even layers,
peening each layer before proceed-
ing with the next, and being careful
to maintain a temperature above
400 degrees Fahrenheit in the area
being repaired. Peening the bead
actually stretches it and counteracts
its tendency to contract and shrink as
it cools. The last layer of weld must
overlap onto the sound metal to
insure a weld without an undercut at
the edges. The overlapping should
be done along this edge by using a
welding rod of 1/8” maximum diam-
eter. The last layer should bring the
height of the welded area up to
1/16” above the original surface, as
checked with a straight edge along
the body bore.
For this type of weld repair, it is rec-
ommended that the last layer be
pounded while still hot with the flat
face of the hammer. Thermal stress
relieving is not recommended.
With a hand grinder, rough grind
the welded surface to within about
.010” of the finished surface. A sim-
ple template cut from thin sheet
metal and having the same arc as
the body bore diameter, and straight
edge laid along the body bore can
be used as a guide. A final cut then
can be made, using a fixture similar
to the one shown in Illustration No.
9, pg. 15. Final finishing can be
done with the adjustable Sunnen
hone described on this page.
After removing all the dirt, chips,
slag, spatter, and grinding dust from
the body, the bore should be pol-
ished with fine emery cloth and then
thoroughly cleaned before reassem-
bly of the valve.
Repair Procedures