Page 233 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Reciprocm'ng Gas Engines and Compressors 215

A word of caution: In each cup having 3-ring construction with a radial
cut ring as part of a sealing element and a radial cut anti-extrusion ring,
the radial cut sealing element when assembled on the rod will have clear-
ance at its joints and is to be placed nearest the pressure source when
positioned in packing cup. The anti-extrusion ring when placed on the
rod will not have clearance at its joints, will be free to turn on the rod and
is placed farthest from the pressure source when positioned in the pack-
ing cup.

TFE Packing Installatlon. When servicing and installing piston rod pack-
ing, the following points should be observed to help prevent packing fail-
ure:

1. The cups, rings, and piston rod must be clean. When assembling
packing on the rod, cleanliness is imperative. Dirt on the ring seat-
ing surface will cause the rings to stick, and dirt on faces of cups
will throw the packing case out of line and permit leakage between
cups.
2. The faces of the cup must be parallel.
3. Position the packing gasket or O-ring in the bottom cup or cylinder
as applicable. Always use a new packing case gasket or O-ring at
this location.
4. The face of the pocket on which the packing case gasket seats must
be clean and free from burrs or scars to provide a flat seat for the
packing.
5. Position the pressure breaker ring in the bottom cup, if applicable.
6. If water cooling is used, see that O-ring seals are properly in-
stalled.
7. Position the next cup on piston rod and butt it against the bottom
cup. Install the radial ring, tangential ring, and anti-extrusion
ring, if applicable. See that alignment dowels are properly
aligned, if applicable.
8. Make sure packing rings SLT~ assembled so that match-marks are prop-
erly aligned and that the proper side of the ring is facing pressure.
Refer to Figures 5-14 and 5-15.
9. Continue installing packing rings, one at a time, until the complete
packing is in place.
10. Tighten the packing case stud nuts evenly to assure proper sealing.
Refer to parts list drawing for tightening recommendations, if
given, or torque recommendations.
1 1. While tightening the packing check with feelers between the bore
of the packing case gland and the piston rod to be sure packing is
being centered over rod. After the case has been installed, the