E-Mail: aavolyn@bellatlantic.net

In packing installations on reciprocating compressors, maintenance personnel have a
tendency to neglect the importance of the packing case. When replacing worn packing rings,
attention must be given to the condition of the sealing surfaces on the packing case sections.
The micro-inch finish of these areas is just as important as the sealing surface of the
packing rings. Wherever possible, these surfaces should be returned to original finishes. For
hydrogen and helium service, the packing cases should be lapped to a ten micro-inch or
better. Also, for pressures over 2500 PSI, lapping should be standard. In lower pressure
service, a ground finish of twenty micro-inch is sufficient for effective sealing. Sealing
surfaces should also be checked for flatness.

A second area to be checked is the depth of the packing cup grooves. Tolerance for this
dimension is +002/-.000. This should be adhered to strictly. Insufficient side clearance is a
major cause of reduced packing ring life.

A third area of concern is a case length under the flange. There should be sufficient
clearance under the flange to allow the packing case gasket to seal tightly against the
cylinder. If the underside of the case flange contacts the cylinder face in the distance piece
before the case gasket seals, there will be leakage around the case. After several
reconditions, the packing case should be returned to its original length.

Many other considerations go into ensuring the proper functioning of packing cases in
service. Thought should be given to maintaining a spare packing case in stock which can be
sent out for professional reconditioning. Then it is available for use in an "as new" condition.
This should more than pay for itself in longer packing life and less loss of production.

616 ORANGE ST.

P.O. BOX 1097

MILLVILLE, NJ 08332

Telephone: 856-327-8040

Fax: 856-327-9595

E-Mail: aavolyn@bellatlantic.net