Saddling pipe: Joining pipe laterals with a saddle beveler

As every pipefitter can tell you, one of the biggest hassles in the trade is making a T joint or a Y joint. Joining a branch pipe to an existing line involves making a hole in the main pipe and a saddle cut on the lateral. The saddle cut sometimes is called a fish mouth because the shape of the cut resembles the open mouth of a fish.

The weld itself is relatively straightforward, but getting the joint ready for welding can be a time-consuming process.

Making the hole in the main pipe usually isn’t too bad. Using a hole saw in a drill press makes this job go quickly and, aside from taking a few moments to get the pipe lined up in the vise just right, nearly every novice can get good results on the first attempt.

Making the saddle isn’t so easy. Pipefitters often use a paper template. After wrapping the template around the pipe and tracing it with a soapstone, marker, or chalk, they use a hand-held torch, plasma or oxyfuel, and rotate the pipe slowly, following the chalk line to make the cut. They also have to take care to keep a consistent angle as the cut progresses.

A paper template isn’t the only way to trace the cut line. Experienced fabricators and pipefitters have all sorts of other methods. A few tools are available to help simplify this part of the process. Some skip tracing the contour but draw reference lines on both pipes and then use a chop saw to make two initial cuts for the saddle. This may sound crude, but the results aren’t bad. However, it’s not a finished saddle yet. It’s only a V, which is the start of a saddle.

Grinding, Guessing, and Grinding When Saddling Pipe

Whether it’s a saddle or a V, it isn’t yet ready for welding. Cuts made by hand aren’t always consistent; cuts made on a chop saw aren’t contoured to match the main pipe. In either case, a good fit-up requires grinding—in some cases, a lot of grinding—to make sure that the main-to-lateral fit-up is good enough for welding.

This is when additional grinding and refitting, and sometimes guessing, come into play.

“Pipefitters grind the branch pipe end, hold it up to the main pipe, and look for gaps and high spots, trying their best to make a tight fit,” said Mitch Trivanovich, sales engineer for Protem USA. While they’re doing this, they have to maintain the branch angle and the branch length as specified on the print.

“Depending on the pipefitter’s skill level, the pipe diameter, and the wall thickness, the process can take from 20 minutes to an hour,” Trivanovich said.

Even when the fit-up is acceptable, the pipefitter might not be finished.

“When the cutting is done by a thermal process, such as oxyfuel, plasma, or laser, the downside is a resulting heat-affected zone,” Trivanovich said. Significant heat input changes the material’s properties, which can affect its weldability and the resultant joint characteristics.

“The heat-affected zone can be eliminated by machining, but this is an additional step that requires additional handling and machine time, which is expensive,” he said.

Making Beveled Saddles in One Step

The struggles with making good saddles help to illustrate the efficiency of using the right tool for the job. Nobody uses a chainsaw for trimming hedges or a sledgehammer for driving finishing nails. The problem in making beveled saddles with the right tool is that such a tool didn’t exist until recently.

A hand-held tool from Protem, model US25GL, is this tool. After inserting the machine’s mandrel into the pipe end and expanding it to lock the machine in place, the pipefitter pulls the trigger and the machine does the rest. In just a few minutes, the pipefitter has an accurately beveled saddle that is ready for welding.

“In addition to providing bevels with dimensional accuracy and consistency, it preserves the metal’s integrity,” Trivanovich said. “Because it’s a cold machining process, the user doesn’t risk changing the metal’s characteristics.” Also, because it doesn’t rely on an open flame, it’s a safer process than some of the other methods.

Furthermore, the machining process is clean.

“It doesn’t generate the airborne dust and debris associated with grinding, which has the potential to contaminate the subsequent welding process,” said Russel Folger, also one of the company’s sales engineers.

The resulting bevel, and land if desired, is perfectly uniform around the branch pipe’s circumference, Folger said. This provides a consistent weld root. Provided with a joint that has a uniform cross section, the welder is prepped for success—full penetration around the circumference is within reach.

“Because the tool has a mandrel that clamps to the pipe’s ID, the tool absorbs all of the torque,” Folger said. This benefits the pipefitter in terms of fatigue and safety. Additionally, the tool can be fitted with a hoist and balancer, thus reducing the chance of repetitive lifting injury, he said.

The standard unit can handle tubes and pipes from 1 inch ID to 4½ in. OD, and custom configurations are available upon request. Cam sets to match the main line’s OD, as well as tooling for common bevel angles, such a 0, 30, 37.5, and 45 degrees, 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, super duplex steels, and INCONEL® alloy. Power options include both electric and pneumatic motors.

Protem USA, www.protemusa.com