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GAR uuul3i how i o ueiect aria avoid ! The Causes Of Packing Failures 3y Clay M. Jewett Gariock Incorporated Palmyra, New York THE WTDE RANGE of chemical solution*, high temperature liquid* and corrosive elements found in modem manufacturing operation* present a number of unusual challenges that must be met by the proper application and maintenance of soft packing materials. As Frank X. Homung. superintendent of oper ations. Allied Chemical Company, Industrial Chem icals Division. Buffalo, N.Y., put it "Proper installa tion is the best way to avoid packing failures. Follow the manufacturer's installation instructions . . . they have done the research and you only ask for trouble when you don't take advantage of their recom mendations." These tips will help you determine additional causes of packing failure. If the packing thickness is unevenly worn, check for badly worn bearings that may cause shaft whip or allow the rod or plunger to wobble. If packing at any one spot around tmrrou .s worn excessively, or if early leakage occurs at any one point around the rod. shaft or plunger, the cause is likely to be misalignment between the shaft or rod. and the stuffing box. If packings are extruded between rod or shaft, and gland follower, the cause may be excessive clear ance between the rod or shaft and the follower. Use of an anti-extrusion ring may be required if the clearance cannot be reduced, or the pressures are high. If the outside diameter of the packing is worn, loose rings may be routing with the shaft due to insufficient gland load or undersized packing. If one or more of the rings are missing, excessive shaft clearance at the bottom of the box may have allowed extrusion of the rings into the system. As a result the packing may be trapped in other equip ment or contaminate the fluid being handled. Re bushing or an anti-extrusion ring is indicated. If one or mote rings have "bulges'* in the facet, the adjacent rings are probably cut too short and the picking is being forced into the voids thus created in the joint area. If the bottom rings are in good condition but the rings next to the gland followers are deformed, the packing wss improperly installed, rings were not in dividually seated, or excessive gland pressure was applied. If a packing problem isn't solved by any of the foregoing, check for OD leakage, as the finish of the stuffing box bore may be too rough. Corrosion, score marks or gouges may prevent a good seal. While the causes of packing failure often are not readily apparent, a careful examination of the used packing wilt frequently pinpoint the underlying causes. Should a packing set fail unexpectedly or after an unusually short time, and the cause is difficult to determine, send it to the manufacturer for examination with a complete description of the ap plication. This may help you rectify a faulty operating condition and prevent future failures. S linden Te PreMeeu Is PM According to Homung. the best solution to packing problems is preventive maintenance. Here are some steps he suggests that yon take to obtain maximum packing life and minimize equipment downtime. Avoid over-tightening. This is the greatest single esnae of packing failure. It is especially important when TFE materials are used. With TFE. take up one-sixth of a turn -- one flat of a hex nut at a time, as opposed to tightening in one or two turn increments as is sometimes done with other materials. Always tighten bolts to evenly distribute the pressure applied by the gland follower. The recom mended method for all packing materials is to gradually *k up opposing bolts. i.e.. where multi bolt glands are used. 12 and 6 o'clock: 3 and 9 o'clock, etc. The extra time required to do this is well worth it leprimed frees Maintenance Engineering Copyright 1971 PLAINTIFFS exhibit; G-380 '