Is Your Gland Packing Leaking Too Much? A Guide to Proper Adjustment

In the world of industrial pumps, two main types of seals reign supreme: mechanical seals and gland packings (also called stuffing box packings). While mechanical seals are precision components for near-zero leakage, gland packings are a more traditional, robust, and adjustable solution.

A certain amount of leakage is actually necessary for gland packings—a few drops per minute is ideal. This slight leakage lubricates and cools the packing rings as they contact the rotating shaft. However, when this trickle turns into a steady stream, it’s time for action. Too much leak means lost product, environmental concerns, and potential damage to the pump.

The good news? Adjusting gland packing is often a straightforward fix you can perform without disassembling the entire pump.

Why Does Gland Packing Start Leaking Excessively?

Before you grab a wrench, it's helpful to understand the why. The most common reasons are:

Normal Wear: Over time, the packing material wears down from friction against the spinning shaft.

Improper Initial Installation: The packing rings might have been installed incorrectly.

Shaft/Sleeve Damage: A scratched or scored shaft will prevent any packing from forming a good seal.

Lack of Lubrication: For certain packings, the inherent leakage provides lubrication. If the seal is adjusted too tight and this stops, the packing can overheat and fail.

The Safe Adjustment Procedure: A Step-by-Step Guide

⚠️ Safety First!

Always follow Lockout/Tagout (LOTO) procedures. Isolate the pump from power before performing any work.

Allow the pump to cool if it has been running.

Wear appropriate Personal Protective Equipment (PPE) – gloves and safety glasses are a must.

Tools You'll Need:

Correct size wrenches (usually two)

A small pick or screwdriver (for adjusting individual bolts if needed)

The Adjustment Process:

Locate the Gland Follower: This is the plate (or "gland") bolted against the stuffing box, compressing the packing rings inside. It's held in place by several evenly spaced bolts and nuts.

Loosen the Nuts Slightly: Use your wrenches to loosen the gland nuts just a quarter to half a turn. This relieves the compression on the packing. This step is crucial if the packing was overtightened and overheating.

Start the Pump: Temporarily re-enable power and start the pump. Allow it to reach its normal operating pressure and speed. You need to adjust the packing while the pump is running to set the correct leakage rate.

Tighten Evenly and Gradually: This is the most important step. Using two wrenches, tighten each gland nut evenly, one flat (1/6 of a turn) at a time. Move in a star or criss-cross pattern (like tightening a car tire) to ensure the gland follower compresses the packing evenly around the entire shaft.

Why this matters: Tightening one nut all the way first will cock the gland follower sideways, creating an uneven seal, causing more leakage, and potentially burning out the packing and scoring the shaft.

Observe the Leakage: After each round of slight tightening, observe the leakage from the stuffing box.

Target: You are aiming for a steady drip, not a stream. A good rule of thumb is 40-60 drops per minute. This slow drip ensures adequate cooling and lubrication.

Warning: If the leakage stops completely, you have tightened it too much. A dry packing will overheat, degrade rapidly, and can score the pump shaft. If this happens, loosen the nuts slightly until the drip returns.

Find the Balance: Continue the gradual, even tightening until you achieve the desired drip rate.

Monitor Temperature: After adjustment, feel the temperature of the stuffing box area. It should be warm, but not too hot to touch. If it's uncomfortably hot, the packing is still too tight. Loosen the nuts slightly.

Re-check After Run-in: Let the pump run for 30 minutes to an hour and re-check the leakage and temperature. New packing will often require a follow-up adjustment after this initial "run-in" period as it seats itself.

What If Adjustment Doesn't Work?

If you've followed these steps and can't control the leak, or if the leak immediately returns to a high rate, the packing likely needs to be replaced. This indicates that the packing material has worn out or been damaged beyond the point where adjustment can compensate.

Key Takeaways for Success

Even Pressure is Everything: Always tighten gland nuts evenly and gradually.

A Little Leak is Good: Your goal is a controlled drip, not zero leakage.

No Hot Running: An overheated stuffing box is a sign of trouble.

When in Doubt, Replace: Worn-out packing can't be adjusted forever.

Properly adjusted gland packing is a highly reliable and cost-effective sealing solution. By following this simple guide, you can ensure your pump runs efficiently, safely, and with minimal downtime.

Need help selecting the right packing material for your application? Contact our experts today for a consultation.

Jack Wan +8615364966178