Page 101 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

86 Major Process Equipment Maintenance and Repair
be cut into rings before installing. Tightly wrap one end of the
packing around the shaft or a mandrel which is the same diameter as
the shaft. Wrap one coil and mark it with a sharp knife. Leave a gap
of 1/16 to l/s in. and mark the ends parallel. After cutting on the
marks, a length of packing may be used as a template for cutting all
the other rings.

3. Remove all old packing, using flexible packing hooks. Be sure to
remove the old packing below the lantern ring.

4. Check the shaft or sleeve for nicks and scratches, remove any that
are present, and then clean carefully. Clean the bore of the stuffing
box. Check the lantern ring to make sure that the channels and holes
are not plugged.

5. Coat at least the outside diameter of each packing ring with grease
or oil.

6. Place the first ring around the shaft and press it evenly to the bottom
of the stuffing box. Seat it firmly against the face of the throat bush-
ing. Rotate the shaft by hand until it turns freely. This helps provide
initial running clearance. Install succeeding rings in the same man-
ner, with each joint 90" clockwise from the preceding one. Each
ring must be seated firmly as it is installed to avoid overloading the
rings next to the gland which do most of the sealing. Whenever pos-
sible, use split bushings as shown in Figure 2-12 to seat each ring
separately. They prevent cocking and compress each ring evenly in
the stuffing box. Wood, babbitt or brass bushings may be used.
When all packing rings are installed, the shaft should turn freely
without binding.

Flgure 2-12. Use split bushings to seat each ring of packing separately.