Ensure consistent joint quality with McElroy’s patented Centerline Guidance

At McElroy, quality equipment is our specialty. And our patented Centerline Guidance, which is included on most of our fusion machines, is another construction method we use to ensure our machines provide results that our customers can count on.

Centerline Guidance is a McElroy-developed, balanced force system that refers to the way force is applied to the jaws of McElroy equipment.

When pipe is clamped inside the jaw of a fusion machine, force must be transferred from the machine and into the pipe itself, to bring pipe ends together and make a successful fusion joint.

During the fusion process, any time force is applied, an “equal and opposite reaction” takes place. Put simply, the pipe “pushes back” against the machine when pressure is applied.  If the fusion force is applied anywhere other than the centerline of the pipe, there will be an imbalance of force on the face of the pipe causing the jaws to want to deflect.

McElroy Mechanical Engineering Manager Paul Donaldson said the concept is like a playground teeter totter. If two children of the same weight climb on, the teeter totter stays level, because they are exerting equal force across the center of the teeter totter. But if a bigger kid gets on one side, that side of the teeter totter goes down, and the side with the smaller child goes up due to the imbalance of force being applied.

“Applying this concept back to our fusion equipment, the balanced teeter totter represents our center line guidance and results in an equal distribution of force between the pipe faces and a straight joint, but the imbalanced teeter totter would be like applying the fusion force off the centerline of the pipe and could result in an angled joint.,” Donaldson said.

So, how did McElroy solve the problem?

On a McElroy machine, force is applied on the horizontal centerline and symmetrically about the vertical centerline. This allows the applied force to be centered, both left and right and from top to bottom.

“It makes sure you’re not twisting the jaws in either the vertical or horizontal plane,” Donaldson said.