Reliable pump and valve packing in 5 steps

Figure 1. Braided compression packing on a spool. (Source: SEPCO)

Step 2: Install packing correctly

If packing is not installed and seated properly, wear, heat increase, and excess leakage are just some of the problems that may arise. Installers should remove all the used packing and the lantern ring. Before installation, they must thoroughly clean the stuffing box and thoroughly inspect the equipment. To achieve maximum performance, the team should inspect the following:

• Gland follower
• Shaft or sleeve
• Lantern rings
• Stuffing box or stuffing box throat

Any issues must be corrected before repacking the pump to ensure that equipment meets the requirements for plant water use and effluent discharge. With assurance that the equipment checks out, the packing must be installed correctly. This means that it is properly seated inside the stuffing box. Improper seating causes many problems, including wear and leakage.

Figure 2. Seating or installation tools ensure that each packing ring is in the correct position in the stuffing box. (Source: SEPCO)

Standard seating tools are recommended so that each packing ring sits in the correct position in the stuffing box (see Figures 2 and 3). The lantern ring must be positioned correctly within the packing rings to provide adequate flushing. This is done by inserting a small object through the flush port and feeling the lantern ring.

Step 3: Observe effective maintenance processes

Proper flushing and maintenance of the packing and its environment are critical. Flushing properly cools and cleans the stuffing box.

The proper flush setup protects the packing, shaft, and stuffing box from excess heat, product buildup, friction, and wear. Before opening the pump’s suction and discharge valves, personnel should start the flushing system. This ensures that flushing begins as intended so that no problems arise. Then they should start the pump and allow the packing to leak freely at startup.

Figure 3. (Left) Installing without installation tools may lead to uneven packing seating and uneven ring loading. (Right) Proper installation, using an installation tool, increases packing life and performance. (Source: SEPCO)

Installation tips

• Stagger each ring’s joints by 90 degrees, beginning at twelve o’clock then move to three o’clock, six o’clock, and nine o’clock.
• Install each ring individually. Make sure each ring sits in the bottom of the stuffing box using an installation tool.
• Use a split bushing or a tamping tool—never a screwdriver or a sharp tool, which could damage the packing rings.
• Seat the rings toward the bottom of the box to accommodate radial expansion

During this break-in period, right after full operation begins, gland adjustments should be made gradually. The team should allow 5 to 10 minutes between adjustments. Taking special care during this break-in results in longer packing life. After break-in, the leakage rate can be controlled to 10 to 12 drops per minute per inch of shaft sleeve diameter.

Step 4: Keep in mind that packing requirements may change as process parameters change

Process operating parameters that were used to specify the packing often do not remain static. As product and process demands change, the plant team should reevaluate the fiber and fiber treatment being used. Changes that may affect the packing type include:

• Flow volume
• Hours of operation
• Operating temperature or pressure
• Material being pumped (such as its pH)

Step 5: Timing of packing replacement

If excess leakage occurs or when the gland adjustment is exhausted, the team must replace the packing. After the break-in period (mentioned in Step 3), the leakage rate can be controlled to 10 to 12 drops per minute per inch of shaft sleeve diameter. As this leakage increases, the gland should be tightened to reach the optimal leakage rate.

When the gland can no longer be tightened, the adjustment is exhausted. At this point, the packing should be replaced because it will no longer seal effectively.