Causes of Gland Seal Leakage

Improper Packing Selection
The selected packing material may not be resistant to corrosion, high/low temperatures, high pressure, or vacuum, leading to seal failure under specific operating conditions.

Insufficient Gland Compression
The packing must be compressed sufficiently to deform radially and fill the gap between the shaft (or valve stem) and the stuffing box. Inadequate compression results in poor sealing performance.

Packing Too Thin
If the packing is too narrow, it cannot provide enough radial deformation under gland pressure, compromising the sealing effect.

Packing Cut Too Short
When packing is cut too short, the ends do not join properly, leaving gaps that cause leakage.

Too Few Packing Rings Installed
An insufficient number of packing rings fails to meet sealing requirements.

Incorrect Installation
Common installation errors include improper cut angles, poor end-face joints, or failure to stagger the joints between rings, all of which affect sealing integrity.

Unsuitable or Degraded Lubricant
The lubricant used for impregnation must provide strong adhesion, effective lubrication, and film-forming properties. If the lubricant is inappropriate or has degraded, the packing won’t function properly. Signs of failure include hardened, cracked, or dry packing.

Improper Storage or Expired Packing
If the packing has aged, cracked, or lost elasticity, it won’t deform properly under pressure, leading to leakage.

Excessive Clearance Between Gland and Stuffing Box
If the gland and stuffing box are mismatched or the gland is too narrow, it won't apply adequate radial pressure to the packing, leading to ineffective sealing.

Damage to Shaft or Stuffing Box Surface
Corrosion, wear, scratches, or broken threads on the valve stem or shaft will compromise the sealing performance.

Bent or Misaligned Shaft (or Valve Stem)
Shaft or stem deformation or eccentricity is a major cause of gland seal leakage.

Packing Too Hard or Containing Particles
Hard or contaminated packing can cause wear to the shaft during operation. Tests show that asbestos packing causes the most severe damage.

Excessive Pump Head
When flow decreases, pump head may rise, increasing internal pressure beyond the sealing capacity of the gland seal, leading to leakage.

Severe Packing Wear
Properly installed packing wears gradually from the gland inward. Poor installation may result in rapid wear near the gland and no wear deeper inside.

Overused Packing
Extended use causes the packing to deteriorate due to wear, corrosion, aging, drying, or temperature effects, resulting in reduced sealing performance and leakage.