When it comes to cutting mechanical packing to seal your pump, there are two primary methods: Skive Cut and Butt Cut.

The debate over which method is superior has been ongoing, with many advocating for one over the other.

One thing is for certain, choosing the wrong type of cut can lead to costly issues with your sealing performance.

In this article, we will dive into the details of each method and discuss the pros and cons to help you determine the best approach for your needs.

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Understanding the Cuts

Butt Cut: A Butt Cut involves cutting the ends of the packing flat. This method is often chosen for its simplicity and speed.

Skive Cut: A Skive Cut involves cutting the ends of the packing at an angle in relation to the shaft. This method creates abetter seal, but requires more time and attention.

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Why Choose Butt Cut? 

Butt Cut is preferred mainly for its expedience. Here are some reasons why people might choose Butt Cut:

●     Lack of Training: Some individuals may not have learned other methods.

●      Time Constraints: The process is quicker, which can be beneficial in time-sensitive situations.

●      Ease of Use: It is straightforward and doesn't require special tools or techniques.

A Butt Cut may also be necessary if the shaft of your equipment isn't centered and you’re having a difficult time fitting your packing inside of your stuffing box.

However, while a Butt Cut is faster, it does not provide the best sealing performance. For example, cutting too short can create leak paths and cutting too long can expand the packing atthe joint, compromising the integrity and causing hot spots and leaks.

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Why Choose Skive Cut?‍

Skive Cut is often considered superior for several reasons:

●     Accuracy: The angled cut provides amore precise fit.

●      Sealing Efficiency: The sharp angle of the Skive Cut helps create a better seal, reducing the risk of leaks.

Despite the advantages, Skive Cut requires more time and careful execution, which can be a drawback in fast-paced environments.

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Methods for Cutting Packing

No matter which cut you choose, here are some methods for cutting packing to help you ensure an accurate seal.

1. Use a Packing Cutter: Packing cutters are available from various manufacturers and offer a quick way to achieve an accurate cut.However, since packing is designed for curved surfaces, flattening it for cutting might lead to imperfect ends. We recommend over cutting initially and then final cutting using a mandrel or on the equipment itself to fix this issue.

2. Use a Mandrel: Using a mandrel allows for a controlled environment, ensuring the most accurate cut, whether you opt for aButt Cut or a Skive Cut.

3. Use the Equipment Itself: Cutting directly on the equipment ensures the most accurate fit for the actual application. However, this method can be challenging due to space constraints and the difficulty of marking and cutting the packing properly.

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Best Practices

Regardless of the method you choose, it's important to cut the packing on the plane it was originally spooled. This approach maintains the integrity of the packing and ensures better sealing performance.

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Final Thoughts

The Skive Cut, though more time-consuming, generally offers better sealing performance than the Butt Cut, making it worth the extra effort in most cases.

Whichever you choose, always inspect each ring on the equipment to ensure proper fit and sealing.

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