Compression packing has become a lost art in the pump industry. However, it can be very effective for certain equipment and processing applications. When done poorly, packing can lead to leaks and excess wear on the shaft. There is a way to pack properly and avoid these problems. Taking the time to do it right will increase the packing life, reduce water consumption, and improve system performance.
Cutting Precise Packing Rings
It is important to focus on the installation process to improve packing results. The first step is to measure the shaft of the equipment. This is critical for pumps, agitators, and mixers. You must utilize a mandrel that is properly sized to the equipment’s shaft diameter. In many cases, you can create your mandrel from materials you may already have, such as old piping, rods, or sleeves that can be fashioned into a perfectly sized piece. Tape can also be used to build the mandrel to the proper size.
The mandrel will be your cutting guide for your packing rings. First, wrap the packing firmly against the mandrel. Then, cut the packing ring at roughly a 45-degree angle with the first joint as your initial guide. The two ends of the packing ring should fit together snugly when wrapped around the mandrel. For most centrifugal pumps, you will want to cut five packing rings and a lantern ring. Each will be sized and cut precisely based on where it is seated along the shaft
Inspecting the Stuffing Box
Before you install the new packing ring, make sure to fully remove any worn packing from the equipment. The stuffing box should be carefully inspected and cleaned before the new packing ring is installed. Taking the time to do everything properly from the beginning will ensure the best results. Being hasty with your packing techniques will only lead to issues that will cost you time and money.
Installing the Packing Rings and Lantern Ring
Another imperative tip is to utilize specialty packing tools designed specifically for packing installation. Don’t just mash the packing rings into the stuffing box with any old tools you have lying around. You will use longer tools for the deepest packing and shorter tools for the shallowest rings. The best approach is to stagger the end joints of each packing ring 90 degrees. In other words, install the first ring. Then, turn the next one to ensure this joint is 90 degrees from the first joint, etc. This is done to separate the weak spots and minimize the risk of leaks.
The lantern ring will be installed last to keep each ring properly seated. You will want to make sure the lantern ring is placed precisely to allow the flush fluid to enter the stuffing box. You can insert a small object through the flush port and assess the ring placement. Only the gland follower should be used when installing the fifth and final packing ring, with somewhere between 25-30-foot pounds of torque. From here, you will loosen the gland completely and let rest for 30-45 seconds. This allows the packing to relax before you tighten the gland nuts. It should be finger-tight plus one flat.
Equipment Operation, Monitoring & Maintenance
Once you have completed this precision packing installation process, you can start up the equipment and monitor the packing carefully. There should be no more than 10-12 drops per minute per inch of the shaft sleeve diameter. If more significant leakage occurs, there may be problems with the packing. During ongoing operation, look for issues like shaft deflection and changes in the process fluid, flow, or pressure. All of these can affect the stuffing box and decrease the effectiveness of the packing.
For packing maintenance, control the flush to keep the packing clean, lubricated, and cooled. The gland follower force may also need to be adjusted as needed. Precision packing takes some time and practice to get right, but it can be a more effective method for specific pump systems and processing applications.
For help with precision packing installation or other alternatives to packing, contact DXP Pacific today. Let our team help you dial in your equipment for your operational needs. Optimize it for efficiency, performance, and durability.