Why You Should Select Abrasive Chainsaws to Cut Pipe Below Grade

Fortunately, there’s been an important development in how you can provide increased safety for your workers when they must cut through a pipe positioned below grade. It’s a common task that probably sends off all sorts of alarm bells when you face it on a jobsite. The solution to improving the safety for your workers is to provide them with an abrasive chainsaw to make the cut especially when there’s the likelihood of a ductile pipe.

 

Practical Research

Recently, a well-respected group of world-renowned researchers at the Massachusetts Institute of Technology (MIT) conducted a study on the mechanics of saw cutting pipes that are below grade. Their goal was to determine how to limit an operator’s exposure to kickback at pinch points as the cut was completed. Their study compared two commonly used tools; the circular cut-off saw, and the concrete chainsaw featuring an and abrasive diamond chain. 

An abrasive chainsaw differs from other concrete chainsaws. Their cutting chains feature exposed embedded diamonds. This grittier exposure results in more of a grinding action than a tearing action. The result is a tool that can effectively cut metal pipe as well as concrete pipe in trench operations. 

The researchers concluded that chainsaws with the proper abrasive cutting chains are the safest and most productive tool for the application. During both the analytical and practical testing phases, they reported that by grinding through a pipe in a trench using an abrasive chainsaw, such as the PowerGrit® Pipe Cutting Chain, operators can practically eliminate any kickbacks from the saw during removal. The full research results can be found in the peer reviewed article “Investigation of Abrasive Saw Kickback,” published in the International Journal of Occupational Safety and Ergonomics in 2020 [2] https://doi.org/10.1080/10803548.2020.1770529).

 

The Real Operational Benefits

Chainsaws with exposed diamonds that grind through ductile pipe reduce the potential and severity of kickback as the operator makes that final cut of a pipe’s lower surface. 

OSHA defines kickback as an event “when the blade ‘catches’ the stock and throws it back toward the operator.” When cutting lumber, kickback is caused when the blade’s sharpened teeth on the wood-cutting chain or blade bore into and grab the wood. 

But researchers found that when pipe-cutting, the kickback an operator experiences, especially when it’s below grade, is different from the causes of wood-cutting kickback. Pipe-cutting kickback is that sudden catch that happens when the circular saw blade or chain bar is pinched by the pipe being cut. This increased exposure occurs when nearing the end of the cut, when only a small section of material typically remains on the underside or belly of the pipe. 

When cutting pipe below grade, kickback exposure is even more dangerous. The pipe, often made of ductile iron, plastic, or concrete, has been in position for a while. The pipe is often under unforeseen loads from the overbearing soil, the excavation itself, or its own weight. These forces often cause a slight pinching action, even on well braced pipes. A subtle pinch can happen very quickly, often without any warning. 

In the MIT university research study, engineers compared and quantified the kickback energies that circular cut-off saws and abrasive chainsaws often receive at that pinch point. Researchers concluded that the kickback energy a circular cut-off saw operator is exposed to is nearly twice the amount operators received when using an abrasive chainsaw, given the same environmental conditions. This conclusive data verifies that using an abrasive chainsaw is the safer option for cutting ductile pipes in the trench compared to a circular cut-off saw.



2.     Abrasive Chainsaws Reduce Trench Size

In addition to providing a tool with less kickback when cutting pipe, choosing abrasive chainsaws can benefit your crew by reducing the size of a below-grade working area. Small work areas in turn can reduce operational costs. 

When you are using an abrasive chainsaw in the trench, less excavation is required. The length of the bar offers an increased cutting depth – and allows the operator to remain stationary, making a top-to-bottom cut with more control.

 

3.     Abrasive Chainsaws Are Ergonomically Better For This Task

Abrasive chainsaws often provide the operator with a better cutting position. This is especially true for that last cut on the pipes. The amount of the upper section of the chainsaw blade guidebar exposed to pinching (aka: the “Kickback Zone”) is much less than the kickback zone exposure of a circular cut-off saw blade. This better position mitigates the operator risk to muscular injury due to positioning, or shock from a kickback, should it occur. And repositioning the blade guard on a cut-off saw is not only dangerous, but awkward – and is a non-issue with an abrasive chainsaw. 

Even with smaller excavations, abrasive chainsaws allow operators to have a safer working space. The pipe’s lower surface is often just above the working floor – a less than ideal position. By using an abrasive chainsaw, operators no longer need to awkwardly position themselves by the cut, as they do with a circular cut-off saw. 

And with a better cutting position with respect to the pipe to be cut, operators using abrasive chainsaws have more tool control, than when they use a circular cut-off saw to perform the same cut. Researchers confirmed this fact when they studied the ergonomics of pipe cutting. With a circular cut-off saw, the operator’s grip wasn’t as consistent as compared to how the operator held an abrasive chainsaw. Operators must use a variety of contact angles to cut through the pipe, shifting the circular saw blade’s orientation, and thus the operator’s grip on the saw shifts throughout the process.

 

4.     Abrasive Chainsaws Eliminate A Common Practiced Safety Violation.

When working in tight conditions with a circular cut-off saw, the operator often pulls back the blade guard to make a cut. This practical, but non-recommended method, exposes the operator to potentially dangerous situation because there’s no protection from the blade should kickback occur. And this unsafe practice happens when the chances of kickback are the highest and the operator’s direct exposure to the blade is the riskiest. 

It’s not only unsafe, but the practice is a potential OSHA violation. OSHA rules mandate that circular saw’s safety guards must never be repositioned. 

When you supply your operators with an abrasive chainsaw to cut ductile pipe, you engineer away this safety concern.

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Visit https://icsdiamondtools.com/kickback-study to view the full independent research study or connect with an expert to learn more about safer alternative cutting methods. Reach out to your local White Cap Representative to request a demo.