Rings of braided or die-formed graphite, PTFE chevrons, or composite materials sit in the stuffing box and are squeezed by the gland so they press against the stem. Too little load and the valve leaks; too much and the stem binds and wears. Live-loaded packing uses stacks of disc springs on the gland studs to keep load on as the rings consolidate, and low-emission packing sets are tested to fugitive emission standards.
Gate on the condensate line has packing smoking at the stem, give the gland nuts a flat each and see if it takes up.
Tighten gland nuts evenly, a flat at a time; cocking the gland follower is how you score a stem.
Also heard as
- stem packing
- stuffing box packing
Related terms
Gland
The part that presses down on the packing to load it against the stem, adjusted by the gland nuts.
Stem
The rod that carries motion from the handwheel, lever or actuator through the bonnet to the closure member.
Fugitive emissions
Small unintended leaks of process gas or vapor to atmosphere, mostly from valve stem seals and joints.
Weeping
Leaking a drop or wisp at a time from packing, a gasket, a threaded joint or a casting.
Repack
To pull the old packing out of a valve stuffing box and install a new set of rings.