Installation Of Braided Packing

A Guide to Proper Pump Packing Installation

Correct pump packing installation is critical to sealing performance and service life. Many premature packing failures are not due to product defects but to improper installation. Following this step-by-step procedure will help ensure a reliable, long-lasting seal.

Step 1: Preparation and Inspection

Begin by removing all old packing rings from the stuffing box. Thoroughly clean the box and the shaft/sleeve, inspecting the sleeve for significant wear or scoring. Replace the shaft sleeve if any damage is found, as a rough surface will rapidly destroy new packing.

Step 2: Selecting the Correct Packing Size

To determine the proper cross-section:

• A. Measure the shaft diameter inside the stuffing box (this is the ring's I.D.).
• B. Measure the inside diameter of the stuffing box (this is the ring's O.D.).
• C. Calculate: (O.D. - I.D.) ÷ 2 = Required Cross-Section.

Step 3: Cutting the Packing Rings

The most accurate method is to cut rings on a mandrel with the same diameter as the shaft.

• Wrap the packing snugly around the mandrel (avoid over-stretching) and cut each ring squarely.
• Pro Tip: After cutting the first ring, use it as a master template to ensure all subsequent rings are identical.
• For diagonal (skived) cuts, use a miter board to maintain a consistent angle.
• Crucial: Precise ring sizing is essential; improperly cut rings will drastically reduce service life.

Step 4: Installing the Rings

Install rings one at a time, ensuring they are clean and free of debris.

• Lightly lubricate the shaft and stuffing box bore if recommended.
• Use a tamping tool to firmly seat each ring individually.
• Stagger the joints of successive rings by 90 degrees to prevent a direct leakage path.
• Once enough rings are installed for the gland to reach them, use the gland itself to assist in final seating.

Step 5: Initial Gland Adjustment

After installing the final ring, position the gland and tighten the bolts finger-tight. Start the pump and gradually tighten the gland bolts evenly until leakage is reduced to a minimal, steady drip (approximately 40-60 drops per minute). Avoid overtightening at startup, as this will create excessive friction and heat, causing the packing to fail prematurely.

Step 6: Run-In and Seating

Allow the packing to leak freely during the initial run-in period (first 30-60 minutes). This leakage cools and lubricates the packing as it seats itself. Gradually tighten the gland in small increments until leakage stabilizes at a target rate of 10-12 drops per minute per inch of shaft diameter. Never attempt to achieve a drip-tight seal unless explicitly approved by the packing manufacturer.

Step 7: Lantern Ring and Lubrication

If the pump is equipped with a lantern ring (seal cage), ensure it is correctly positioned slightly offset from the fluid inlet port. When specified, connect and activate the external lubricant supply (water, oil, or process fluid) to the lantern ring to ensure adequate cooling and lubrication.

Step 8: Understanding Packing Wear

Recognize that approximately 70% of wear occurs on the two rings nearest the gland. The remaining rings act as a safety reserve, providing redundancy so that a single ring failure does not necessitate an immediate shutdown.

Special Installation Notes:

• For Spiral Coil Packing: Never wind bulk packing directly into the stuffing box. It must always be cut into individual rings before installation, following Steps 1-8.
• For PTFE or Graphite Yarn Packing: Exercise extra care during seating. These softer materials require gentle, gradual tightening after the pump is operational.

By adhering to these guidelines, you can maximize packing life, minimize maintenance downtime, and ensure optimal pump performance.