Page 146 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Becaust the last ring of packing requires more lubrication than do the
others, lubrication of the pachng from the atmospheric side is mure ef-
fectivethan injection ofoil into alantern ring located in the center ofthe
packing. Care must bt exercised to get the lubricant onto the plunger sur-
face and close ewugh to the last ring, so that the stroke ofthe phmger
will carry the lubricant under the ring. If the lubricant drips onto the
plunger aft of the gland, the plunger-stroke length may not be sufficient
to carry the lubricant under the last ling of packing.
Because the last ring of packing deforms the most, it conforms to the
irregularities in the bore of the stuffing box. Therefore, when the gland is
tightened, most ofthe force is absorbad in the last ring, causing it to seal
tighter in the box and on the plunger. kry little of the gland force gets
transmitted to the inmr rings of packing.
Hence, the bottom ring of paclang must be firmly seated during instal-
lation, using a rod with a flat end or a stack of gland bushings. After the
stuffii box has been completely assembled, with the plunger rein-
stalled, and before filling the liquid end with fluid, it is advisable to
tighten the gland snugly by hand with the gland wrench. If allowed to sit