NIBCO Bronze Gate Valves - Manual (Page 7)

NIBCO Technical Services • Phone: 1.888.446.4224 • Fax: 1.888.336.4224
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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. After 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 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. Tighten as required.
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 can be used 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.
C. Combination oil stone, flat plate glass will be used and fine 400 grit sandpaper to
polish the wedge. Flat plates to check high spots on flat surfaces such as bonnet,
seal surface and wedge in conjunction with machinist blueing.
6.0 SPARE PARTS
Normal spare parts to be maintained on hand are listed on the NIBCO spare parts list
(see Appendix).
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
to give the serial letter because over a period of time the valve designs have had
modifications which could render the parts useless if they are of a different letter series.