Packing, Tapes and Threads

Compression packing, sealing tape and cord seal shafts and stems in industrial equipment. The category includes braided packing, preformed rings and cord-form sealing products for installation around moving components.

Compression packing is a shaft seal compressed in a stuffing box around a shaft or stem. Lubrication from the sealed medium or an external lubricant removes heat and helps prevent the packing from burning. Preformed rings are manufactured to the required shape and density before installation.

These seals are used in valves, control valves, plunger pumps and mixers. Products are available for industrial duties and food-industry applications. Graphite rings are used around valve stems, while compressed tape rings can seal self-sealing covers in high-pressure boiler-feed-water valves.

First establish whether the equipment requires braided packing, a graphite-tape ring, a preformed set or sealing cord. Then match the yarn or material to the medium, the lubrication method and the position in the valve, pump or mixer. Also check stuffing-box dimensions and whether a split ring is needed for assembly around the shaft.

Material options include ramie, aramid, PTFE, carbon, graphite, GFO and silicate; preformed graphite tape rings can include steel reinforcement where extrusion must be limited.

Frequently asked questions

Lubrication removes heat from the contact area. The sealed medium can provide this function, although an external lubricant may be required. Insufficient cooling can cause the packing to overheat and burn.

Preformed graphite rings commonly seal valve stems. They are formed from graphite tape and compressed to the required density. A split version can be fitted around an existing shaft or stem without sliding the ring over its end.

Compression packing can be made from ramie, aramid, PTFE, carbon, graphite, GFO or silicate yarns. Select the material for the medium and duty rather than choosing from the cross-section alone.

Steel reinforcement is relevant when a compressed tape ring needs resistance to extrusion. One stated application is a ring for a self-sealing cover in a high-pressure valve used for boiler feed water.