A challenge that modern pulp and paper mills are facing is to lower operational costs. The highly competitive global market place forces plants to reduce expenditure and extend equipment life. In addition environmental legislation put restrictions on the way that plants operate.

A large portion of rotating equipment in this industry is sealed with mechanical packing. The functional life of mechanical packing has everything to do with the generation and effective removal of frictional heat. Friction is kept to a minimum by the use of low friction materials such as PTFE and graphite as well as the use of friction reducing additives in the packing’s braided structure. Materials with a high coefficient of thermal conductivity are preferred to dissipate heat away from the heat source.

Mechanical Packings are designed to operate in clean fluids. The specific challenge faced in the pulp and paper industry is the high content of solids in the pumped fluid which has a significant effect on the life of the mechanical packing. By nature, packing life is counter proportional with solid content (Fig. 1) .

Fluid particles tend to embed themselves in or accumulate under the packing surface increasing frictional heat. These particles tend to eliminate the positive properties related to friction reduction and heat dissipation given to the packing material and design. Additionally, accumulation of solid particles restrict the fluid circulation required for cooling. Extending the life of mechanical packing is achievable by cleaning up the environment it is operating in.

Traditionally, flush water injection is used to solve this problem. The flush water cools the packing and takes particles away from the dynamic sealing area. However, environmental laws as well as high operational costs associated with flush injection have put restrictions on the amount of water that plants are allowed to use.

Nowadays, more advanced technologies exist that allow effective solids removal while minimising the amount of flush injection at the same time. One such technology is the SpiraITrac environmental controller. The SpiralTrac technology takes a different approach to cleaning up the mechanical packing’s operating environment. It uses the rotational speed of the fluid including its suspended particles and converts it through centrifugal action into an axial movement.

By design, the SpiralTrac technology takes advantage of the existing rotational flow and directs particles away from the mechanical packing expelling them out of the stuffing box. The challenge has been to find the optimal design for existing pump geometries, speeds, fluid properties and equipment orientation that allows the build up of sufficient kinetic energy to force the particles out of the stuffing box. Computational Fluid Dynamics make it possible to simulate the functioning of the SpiralTrac technology. The various parameters can be toggled in a virtual environment to simulate and visualise the fluid and particle flows.

With the patented SpiralTrac technology water usage can be reduced drastically and in some case be eliminated completely. At the same time, the technology extends the mechanical packing’s life considerably as particles are kept away from the packing set where they could cause damage.

The application of the SpiralTrac environmental controller in combination with performance packing truly creates an enhanced sealing solution that offers greatly reduced flush water usage with reduced need for maintenance while extending packing life considerably. It has been successfully applied in refiners, mixers, agitators, pulpers and many other types of equipment commonly found in the pulp and paper industry. It can be supplied either solid or split for ease of installation without the need for equipment disassembly. Materials can be selected according to process requirements from a variety of materials such as stainless steel, glass or carbon filled PTFE.

Controlling Gland Packing By Hans Dekker, Product Manager, Mechanical Packing & Gasketing

Mechanical packing is a versatile sealing device. One of the best features of braided mechanical packing in roll form is its flexibility and ease of use. In today’s world of maximizing plant efficiency with limited maintenance resources, some important steps to follow when installing packing are often overlooked. One of these is properly cutting the braided packing.

One of the best ways to enhance packing life is to focus on installation. After packing is installed, a few fixes can prolong life when a leak has occurred. As Ben Franklin stated, “An ounce of prevention is worth a pound of a cure.” This is true about packing, since installation is the key to long packing life. Cutting packing rings incorrectly can result in a low mean time between failure (MTBF) for valves and pumps and is easily preventable with some basic training. This article discusses some fundamental concepts to improve packing life by properly cutting the rings.

Important Steps

The best way to cut packing accurately is to focus on a few simple steps:

• Use a mandrel to cut rings
• Use a sharp knife
• Use a forceful cutting motion

Sometimes, bad habits that are developed when cutting packing rings can start at a plant and can severely limit packing performance. Training and education will help prevent bad maintenance practices and provide understanding of the importance of the task. Unacceptable practices for cutting packing rings can be handed down from technician to technician because it is hard to see the effect that it has on the sealing failure of the equipment.

Sizing

One of the more prevalent practices is using the packing rings that were removed when unpacking a valve or a pump as a length guide for cutting the new rings. The problem is the rings that were removed could have been incorrectly sized the last time so the error will just be repeated. Also, the rings that are unpacked might have been chemically attacked and may have shrunk or become deformed while in service.

The most accurate way to cut packing rings is to use a mandrel that is the exact size of the shaft or stem. By taking the mandrel and placing it in a vice and wrapping the packing around it, an accurate length can be determined for the packing ring.

Figure 1. Checking Ring Size Cutting

Cutting

The rings should either be cut on the mandrel at a 45-degree angle for a skive cut or a 5-degree, almost-straight cut for a butt cut. Check the installation instructions of the packing manufacturer for the correct cutting type required by the application. Rings should be held tightly on the mandrel but not stretched. When cutting skive joints, a mitre board should be used so that each successive ring can be cut at the correct angle.

After each ring is cut, it should be wrapped around the mandrel as a double check to ensure that the ends adjoin with each other. This is similar to a “go/no-go” gauge. Skilfully cutting rings with a mandrel does take some practice of the packing pulling and the wrapping technique. Focusing on the end result of the ring fitting on the mandrel with no gap will quickly provide a feedback loop to perfect the practice. Each style of packing will pull around the mandrel slightly differently.

Figure 2. Cutting on a mandrel

Figure 2. Cutting on a mandrel

Unravelling Ends

Another issue to watch for is trimming rings that have been cut long. Cutting a small section of one of the packing ends can result in the packing unravelling—a major failure point when it is installed. If this happens, the damaged ring should be scrapped, and another ring should be cut, concentrating on getting the size correct.

Tools

The second component to an accurately cut packing ring is the tools that are used. Another major poor practice is using a pocket knife to cut packing rings. A number of major issues can arise from using this type of cutting tool.

The first problem is that most knives are not very sharp, and a dull knife will make the cutter use a back and forth cutting motion instead of clean slice of the packing. This back and forth motion causes the packing to open up (bloom) making installation and sealing more difficult. A sharp knife makes a clean cut that keeps the strands together in the original shape. Cutting packing will dull any type of knife quickly, so make sure there is easy access to knife sharpeners.

The second issue with using a pocket knife is the lack of a good grip. When cutting packing, a considerable amount of force must be applied to cut in one stroke, and without a good handle, this is much harder to accomplish. It is very important that the tool used to cut packing is a straight edge blade and not serrated. This will also help reach the goal of a clean cut without deformed packing ends.

The correct way to cut packing is to have the knife at an angle to the packing (handle higher) and not parallel to it. This method results in better leverage on the packing resulting in a better cut. Many tutorials are available that highlight this method when cutting in the kitchen. Correctly cutting a piece of packing is very similar to cutting in a professional kitchen

Excess Material

Cutting packing will always results in some waste. This could be rings that are too long or short but also can be rings whose ends have unravelled or blossomed to the point at which they could result in a leak path. One of the easiest ways to sidestep errors in cutting is to order cut rings from the packing supplier. Besides no scrap, there is also a considerable time savings from not having to cut the rings. The drawbacks to using cut rings everywhere is having good documentation of the actual size of the packing beforehand to know what to order. This can be a bigger hurdle than first thought since a major paradigm shift needs to occur regarding creating a database of equipment dimensions.

Conclusion

A couple of other simple ways to create a good environment that will result in a better cut ring are first to order (or get a machine shop to create) accurate mandrels for all stem and shaft sizes. The other is to have in the cut ring area some good knives and access to a knife sharpener

Written by Ron Frisard of the AW Chesterton Company

PUMPNSEAL is proud to offer and service the full range of Chesterton mechanical seals for pumps, agitators, mixers, and other rotating equipment. Our proven component, gas, cartridge, cassette, split, and mixer seals are specifically designed to simplify installation, improve the reliability, and extend the performance of your fluid handling equipment. Our most popular are the innovative 442 split mechanical seals which have sealed up to 915mm shafts! At PUMPNSEAL we offer full seal refurbishment for all manufacturers.

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With Chesterton’s continuous research and state-of-the-art advancement, PUMPNSEAL offer a full-line of packing and gasketing technology that delivers the highest performing sealing systems for a wide range of applications. Our packing’s and gaskets offer maximum reliability and low leakage rates for maximum impact. Chesterton offers mechanical packing’s for a variety of equipment, including but not limited to pumps, mixers, blowers, fans etc. performing under a wide range of operating conditions. Chesterton sealing systems are the leaders for leak free performance.  If you are planning repacking valves, and want to get the job done in a fraction of the time, consider utilising our Water Jet Packing Extractor (see video link).

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PUMPNSEAL carry a large inventory of end centrifugal ANSI & ISO process pumps for a broad range of duties and budgets. Our premium System One pumps are an innovative line of high-strength, low maintenance process pumps designed specifically for the toughest, most extreme environments and have set the industry standard for high quality and durability.
Features exclusive to Blackmer’s System One ANSI pumps include:

• Designed around the mechanical seal and bearings where 90% of failures occur;
• Designed to maximize system reliability – stronger, more vibration-resistant pump;
• Heavy-duty, solid, low deflection shaft prevents common vibration damage and greater stability at the seal area to improve seal life;
• Heavy-duty bearings offer greater load capacity and extend bearing life;
• Patented System One® Labyrinth Seals provide non-wearing lifetime protection for radial and thrust bearings.

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If you are looking for sealing solutions for hydraulic cylinders, pneumatic or rotary equipment, PUMPNSEAL can help fast. With local Chesterton seal manufacturing capabilities we can provide the quick service you are looking for along with superior materials and technical support.

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The Inpro/Seal Company manufactures a Bearing Isolator that will provide the highest level of bearing protection available. Inpro/Seal® Bearing Isolators are made of high quality bronze and are designed to last for at least 100,000 hours compared to the common lip seals which usually fail after only 3,000 hours. With the latest engineering and manufacturing technology Inpro/Seal can meet your reliability requirements with seals designed specifically for your equipment with quick, timely deliveries.
This two-part dynamic seal consists of a stator press-fitted into the bearing housing and a rotor attached to the shaft. The rotor and stator form a non-contact, compound labyrinth, so there is nothing to wear out
It protects two ways:

• Bearing lubricant is captured in the inner portion of the labyrinth and flows back to the bearing housing
• Outside contamination attempting to enter the bearing housing is captured in the outer labyrinth paths and expelled through a port in the stator by centrifugal force and gravity

At PUMPNSEAL we offer full seal refurbishment for all manufacturers. No matter the size or complexity, Inpro-Seal and PUMPNSEAL’S team can design a custom seal for your equipment.

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PUMPNSEAL in conjunction with Chesterton’s Global Training group offers a variety of educational services. Contact us to find out when our next upcoming training sessions will be held. Popular courses are:

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• VALVE SEALING PROGRAM

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Want to get training without traveling? Discover Chesterton’s array of award-winning, online courses available to you 7 days a week, 24 hours a day. From this area, you can also log on or register to create an account. PUMPNSEAL can also bring the training to your location with our mobile pump training unit that can bring the hands on experience along with the theory

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At PUMPNSEAL, we are a Chesterton factory authorized repair centre well equipped for repairing and testing of all mechanical seals. With full lapping facilities we offer a speedy turnaround service. We also offer a comprehensive training programme for mechanical seal installation and application.

With PUMPNSEAL’S water treatment division, Superior Water Australia offers a comprehensive service which includes supply, installation and ongoing scheduled maintenance programs for keeping your highest water quality standards.

Superior along with PUMPNSEAL lead the way in customer support by offering 5 chlorination items guaranteed for life! This means no more expensive diaphragm replacements, no cracked regulator bodies and no corroded bolts and screws, giving you a more reliable system and a lower cost of ownership.

From 16 gr/hr to 40 kg/hr, Superiors Gas Chlorination system offers a variety of options including vacuum and pressure manifold systems with configurations from single bottle to multiple bottle systems and tonne container connections. These systems also include accessories such as gas detectors, auto‐valves, manifolds and analytical instruments.

• Gas Regulators suit cylinder/tonne containers
• Auto-changeover systems
• Auto Valves
• Leak Detectors
• Analysers
• Scales
• Shutdown Systems

To assist in your application please call one of our specialists at Superior Water division on

1 300 656 493