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Reliable pump and valve packing in 5 steps

March 10, 2020
Stuffing box reliability depends on proper packing installation, operation, and maintenance.

A common sealing technology, compression packing (also just called packing) is used to prevent product leakage in pumps and valves. This article focuses on installation, operation, and maintenance in pumps.

Following some best practices can help you increase the life and effectiveness of your compression packing. These best practices will also help ensure that equipment in your plant meets requirements for plant water use and effluent discharge. By adhering to the five steps detailed in this article, plant teams can all but eliminate excessive leakage and reduce downtime.

Click here to view the infographic "5 Steps for Reliable Packing Performance"

Step 1: Choose the most effective base fiber and fiber treatment

The correct braided packing must be chosen with an emphasis on the chemical and thermal properties of the fibers (see Figure 1). Consider these criteria as well: operating temperature, pressure, shaft speed, and pH range. Next, plant teams need established processes for the basic packing installation, equipment operation and maintenance, and inspection guidelines.

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)

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.

About the Author: Chuck Tanner

Chuck Tanner is director of market development for Sealing Equipment Products Co., Inc. He has more than 30 years of experience in the pulp and paper industry and has been with SEPCO for 27 years. Tanner may be reached at [email protected].

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