relied upon. Vigilance and hand-operated, quick-acting valves afford the
only reliable means of controlling pressures. There are two types of quick-
acting valves that are satisfactory for the grout lines. These are the so-
called lubricated and nonlubricated plug valves. Lubricated valves should be
installed throughout the entire system except for the first valve above the
grout hole, where a nonlubricated valve should be used. They should be of a
diameter to fit the pipe size, have threads inside, and should be capable of
withstanding nonshock, cold water pressure equal to at least the maximum
pressure to be applied. Both body and plug should be made of iron or semi-
s t e e l . The plug of the valve should be ground into its body to ensure perfect
contact over the entire surface of the plug and to give smooth operation and
perfect seating. The valves should be square headed, similar and equal to
Walworth Company' s standard iron cock No. 651.
PACKERS.
18.
Introduction. There are three general types of grout packers in
a.
common use, the cup leather, the mechanically expanded rubber ring, and the
pneumatically expanded rubber sleeve. Various methods of mechanically ex-
panding the rubber ring or rings have been used, and each has its place for a
particular condition. No effort will be made to illustrate all of the packers
that have been used as all types are frequently modified and improved to fit
local conditions. Each general type does, however, have characteristics
making it most suitable. Initially, AX (2-in.) or BX (2-3/8 -in.) holes were
thought to be the smallest size adaptable to the use of packers, but now they
have been developed for all sizes from EX (1-4/2-in. ) to NX (3-in.). Some
difficulties arise when smaller holes are used. The packers to be described
here are all for EX size holes.
b . Cup Leather Removable Grout Packer. The cup leather type shown
in figure 18 is best suited to fairly hard rock where the drilled hole is not
oversize and the walls are relatively smooth and true. This packer when
suitably anchored has been used successfully for grouting pressures up to
750 psi. It is simple to construct, easy to maintain, and only requires a
single pipe to lower it in the hole. Where high grout pressures are feasible,
it is probably the best type of packer to use. If it should accidentally become
stuck in the hole, a right-left coupling enables the crew to save the supply
pipe string and the packer itself can be drilled out, if necessary.
c . Mechanical Packer. The mechanically expanded type shown in fig-
ure 19 is adaptable to softer rock than the cup leather type, but it may be
difficult to seat if the drill hole is too much over size. Its positive expanding
action gives it an advantage in that it can be positively seated at any location
if the hole is not too enlarged. When used at depths greater than 20 ft, flush-
joint tubing is required and it is somewhat award to handle in a deep hole.
Once seated the packer too can withstand fairly high pressure and has been
used on many jobs.
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