Automating thread inspection on tubular goods

According to Autonetics LLC, automated gaging units (AGUs) for threads are hot. The Cary, N.C.-based AGU manufacturer reported that it shipped 10 systems in the third quarter of last year to U.S. pipe mills that produce oil country tubular goods. No shipments occurred in the fourth quarter because the industry experienced a downturn, so capital expenditure projects got cut or delayed, noted Jeff Heath, COO of Autonetics. However, he said, the projects are starting to receive funding again. “We have about four in the build phase.”

A sensor head on an automated thread gaging unit from Autonetics. Image courtesy of Autonetics.

Typically, pipe mills rely on two quality inspectors with manual gages to man a production line, one on each side of the pipe, who measure the threads of every 10th pipe, Heath explained. “It’s a demanding job in a very difficult, dangerous environment,” he said. “You have a 40′-long pipe that weighs hundreds of pounds clambering down the production line.”

And because even the best inspector is still human, the process is error-prone, Heath added. “The manual gages are not reliable when they are put into human hands.”

A thread-measurement robotic cell eliminates that human element and enables the threads to be measured on every pipe in about 30 seconds, Heath said. Each robotic cell can inspect the threads on pipes from 2 3/8″ to 16″ (60.3mm to 406.4mm) in diameter without impeding production.