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Causes of packing failure
 In addition
to the impact that improper packing material selection can have on both
packing and pump performance, two other areas can contribute to packing
failure. One is improper installation of the packing, the other is
faulty pump equipment. To determine which factor is the cause of packing
failure, look for clues in the old packing. If the packing you've
removed is thinner in one area of the inside surface, then the shaft is
improperly aligned. If there is raggedness or shredding on the inside
surface, you'll probably also find chipping or burrs on the shaft
sleeve. When the old packing has become hard or abrasive, it's an
indication that either the wrong packing material was used, or the
stuffing box is worn, (pores are damaged or clogged), causing the gland
water to flow outside the packing rings and not cool them properly.
If one or
more rings are missing, or if there is partial extrusion of the inside
ring, you have too much throat clearance and you'll need to install a
bull ring or anti-extrusion ring. On the other hand, if the outside ring
shows evidence of extrusion between the shaft and the follower, there is
too much gland follower clearance. This can be corrected with the
installation of a bushing or by reducing the gland pressure to reduce
the gap. A careful analysis of the old rings and inspection of the
stuffing box and shaft sleeve should tell you what is causing your
packing to fail prematurely.>>The
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