Stages in the life of packing

The packing rings must totally fill and occupy all free space inside the stuffing box. The rings are composed of active and passive fibers (the passive fibers act as carriers to string and braid the active fibers). The packing also is impregnated with internal lubricants and bathed in surface lubricants. When the gland is tightened, the packing begins compressing and heating. The lubricants will eventually extrude out of the packings and the passive fibers will normally burn and carbonize into ashes. As the packing wears, it loses volume. There are generally four stages in the life of a packing ring:

1. Stage one is when the packing rings occupy the full space inside the stuffing box.

2. Stage two is when the packing gland has been tightened and the packing compresses. The space occupied in the pump is reduced.

3. Stage three is when the lubricant has extruded from and left the packing. At this point the packing should be changed

4. Stage four is when there is no lubricant and the carrier fibers have disintegrated into ashes. The packing becomes hard from calcification and destroys the shaft or sleeve.

Stage four packing should never be in the pump. It should be changed at stage three. When the gland follower butts against the stuffing box mouth and the gland nuts can no longer be tightened, then you've reached stage four. Stay away from stage four in the life of your packing rings.

Mechanical Seals

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