Properties of Good Gland Packing

To be successful in its duty and to attain the objective of successful sealing and trouble free operation the gland packing must have the following properties.

Anti-friction properties. The gland packing basically rubs along the shaft and stationary along the stuffing box side. If the gland packing has friction it would score the shaft or the shaft sleeve and also would heat up and fail and even burn due to consistent overheating.

Chemical resistance to the fluid being contained. If the gland packing reacts with the fluid it is supposed to seal it would later disintegrate and be flushed away leading to leakage of the fluid which is not desirable.

Temperature resistance. The gland packing should be able to resist the working temperature of the fluid being sealed without failing.

Compressibility and resilience. The gland packing should be able to compress and confirm to the shaft under the force of the gland flange and when the tension is released it should come back to its original shape. The latter is important as when the gland nuts are loosened the gland packing should spring back releasing the shaft.

Retention of lubricants. All the gland packings are coated with lubricants like graphite, grease, petroleum products etc., also external lubricant is applied before insertion. The gland packing should be able to retain this grease for anti-friction properties.

Should not score the shaft. Normally on pumps a shaft sleeve is inserted over the portion where the gland packings are inserted and which is replaceable. The gland packing should nonabrasive to avoid the scoring on the shaft sleeve. Of course on a long interval this is not possible, but it should at least sustain till the next overhaul Should not contaminate the fluid being sealed. In some applications like food and pharmaceutical industries the gland packing should not contaminate the fluid, while in others it does not matter.

It should be non-corrosive to avoid damage to the shaft and the housing.

It should be wear resistant to last a long time.

It should retain its property over a time period.