Using Protem model US25GL, in a few minutes a pipefitter can create an accurately bevelled saddle ready for welding.
One of the most frustrating issues pipefitters have to tackle is making T joints and Y joints. Joining a pipe to an existing line requires making a hole in the main pipe and a saddle cut – sometimes called a “fish mouth” because of the shape of the cut – on the lateral.
Welding such a joint is relatively hassle-free, but preparing the joint for the weld can be time-consuming and imprecise.
Preparing the hole in the main pipe is generally straightforward; a hole saw in a drill press will get the job done promptly. The only challenge that the pipefitter might have is lining up the pipe in a vise.
The saddle is more of a challenge. Traditionally, pipefitters used a paper template to trace the cut line around the pipe with soapstone, marker, or chalk. Today metal cutting guides can be clipped onto pipes to determine the line. Once the line is on the pipe, it needs to be cut with a hand-held torch, plasma or oxyfuel, while rotating the pipe slowly. A consistent angle has to be maintained throughout the cut as well – not a simple feat.
Another option is to rough-cut a V with a chop saw and then grind out the saddle.
The job isn’t done once the initial cut is complete. No handmade cut is going to be completely accurate, so even when the pipefitter is using a hand-held torch, some grinding will be necessary. And a good fit-up usually requires going back and forth, checking for gaps and high spots to get the best fit.
“This method of preparing a bevel works, but it is very time-consuming, and getting a repeatable bevel that way is not good,” said Matthew Kerbel, service and application engineer, Protem USA, Evergreen, Colo. “If you’re doing one here and there, that’s OK, but if you’re doing a boiler system or network where you have to lay out 50 of these to attach to something else, it is not a very effective approach.”
Some tools now are available to make this process much easier. One of these is a hand-held tool from Protem, model US25GL. Basically, the operator inserts the machine’s mandrel into the pipe end, expands it to lock it into place, then pulls the trigger and the machine does its job. In a few minutes, the pipefitter has an accurately bevelled saddle ready for welding.
“The tool has a cam under the tool plate that essentially oscillates in and out to give you the correct, precise geometry of the bevel every time,” said Kerbel.
One of the other challenges of using a torch to cut a bevel is that you end up with a heat-affected zone on the pipe that inevitably has the potential to affect your weld.
Joining a pipe to an existing line requires making a hole in the main pipe and a saddle cut on the lateral. Welding such a joint is relatively hassle-free, but preparing the joint can be time-consuming and imprecise.
“This tool is a cold machining process, meaning that no heat-affected zones are created in its use,” said Kerbel. “If you are just welding pipe for a waterline that is going to be run at low pressure, that heat-affected zone you get using other processes may not be a huge concern. But if you are doing anything that involves pressure and/or heat, you are going to want to consider a cold-machined process.
“The other issue you are not dealing with using a cold machining process is slag,” Kerbel continued. “Anytime you use a flame beveller, the bevel may be nice, but you have a secondary process requirement involved in removing that slag. It can be time-consuming.”
The extended capacity of the tool is between 1 in. ID and 3.5 in. Cam sets to match the main line’s OD, as well as tooling for common bevel angles, are available in standard sizes. The tooling is available in high-speed steel, coated (TiN or TiNC), and as carbide inserts to accommodate aluminum alloys, carbon steels, stainless steels, duplex steels, superduplex steels, and INCONEL alloy. Power options include both electric and pneumatic motors.
“We haven’t made it yet, but we have plans to put that same head on other machines,” said Kerbel. “So, if someone came to us and wanted to perform a saddle bevel on a 6-in. pipe to place on a 12-in. pipe, we could do that with our US30CH or US40 tools. Our engineering team has planned for this further development of our capabilities. It’s this expertise we’re there to offer our customers.”
If there’s a slight downside to the technology, it’s that it’s necessary to purchase a different cam for each bevel.
“If you have a 3-in. pipe going onto an 8-in. pipe, that’s going to be a different geometry than a 1.5-in. pipe going into a 3-in. pipe,” said Kerbel. “It’s cam-specific to what you need. But once you have the tool to run the cam on, it is easy to swap the cam out for a different size.”
Editor Robert Colman can be reached at email@example.com.
Protem USA, www.protemusa.com
Protem has plans to put the same bevelling head on other machines, such as the US40 tool shown here, allowing shops to create bevels on larger pipe.
Toronto, M1R 0A1 Canada
See More by Rob Colman
Robert Colman has worked as a writer and editor for 20 years, covering the needs of a variety of trades. He has been dedicated to the metalworking industry for the past seven years, serving as editor for Metalworking Production & Purchasing (MP&P) and, since January 2016, the editor of Canadian Fabricating & Welding. He graduated with a B.A. degree from McGill University and a Master’s degree from UBC.
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