NIBCO Bronze, Globe and Angle Valves 1/ to Class 175 WWP - Manual (Page 7)

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Excessive tightening may cause difficult operation of the valve and could cause damage
to the stem or packing nut.
If the gland has run out of travel, isolate and depressurize the valve for repacking or the
addition of more packing. Repacking of valves under pressure is not a recommended
practice. This is dangerous and could result in serious injury even if the valve appears to
be back—seated. Foreign matter may have accumulated on the back seat, or by
accident the stem could be knocked off the back seat position thereby allowing
dangerous fluids to injure maintenance personnel.
Remove the handwheel packing nut and gland to remove the old packing. If the packing
is removed, discard and do not try to put it back once it has been removed. Clean the
stem and examine it for damage. On very small valves the packing is sometimes rope
and is sometimes spiral wound around the stem and pushed into the stuffing box. Install
the new packing which may be one piece purchased from NIBCO or split rings. If it is
split ring rope packing install one ring at a time with the diagonal cut in each ring being
staggered 90° away from the cut in the ring below. Each ring should be firmly
compressed in the stuffing box after it is placed in position before the next ring is added.
Install the gland bushing and packing nut and tighten down. The packing nut should be
tightened only enough to prevent leakage. Pressurize the valve and check the packing
for leakage.
5.0 MAINTENANCE
5.1 TOOLS AND EQUIPMENT
Standard wrenches and tools are suitable for servicing valves as follows:
A. For removing bonnet of the union type – a chain wrench is normally used or the
appropriate socket that will fit the bonnet union nut. For screw in type bonnets –
generally a socket wrench or open end wrench may be used if extreme caution is
used. Pipe wrenches on union nuts or screw in bonnets have a definite crushing
action which will deform the component and are not recommended.
B. A standard packing tool can be used and/or a blunt hook is generally used to remove
packing rings. A screwdriver to raise the packing gland (if it is in the fully down
position) and generally open end wrenches are used to tighten the packing nut.
DOES NOT APPLY TO FIRE PROTECTION VALVES.
6.0 SPARE PARTS
Normal spare parts to be maintained on hand are listed on the NIBCO spare parts list.
If the bonnet or body is damaged, it is normally less expensive to remove the entire
valve from the line and install a new one.
When placing an order for spare parts, it is necessary to give the size, the valve figure
number found on the aluminum identification plate and also the serial letter which is cast
into the valve body on its side. This will be an alphabetical letter, A, B, C, D, etc. It is vital