Drilling pipe is the lifeline of the oil and gas industry. That fact makes the Vallourec Group’s products essential to its customers. Based in France, Vallourec is a leading supplier of drill pipe for energy companies around the globe. The manufacturer has a presence in 20 countries, including Vallourec Drilling Products USA in Houston.
Inside the Texas plant, seamless steel tubes that have been rolled in Vallourec rolling mills elsewhere undergo the final – and vital – step in the manufacturing process. Specially prefabricated tool joints are welded onto each end of the high-strength alloy tubes, which are either 30 feet or 45 feet long.
The threaded joints allow oil workers in the field to interconnect the segments and form long strings of pipe used for drilling pilot holes, both on land and under water.
The industrial process of attaching the end joints to the “mother” pipes begins by machine-forging the ends of the pipe to make the wall thicker there. The pipes then proceed to heat treatment where the strength and toughness of the product is achieved. After heat treatment the tubes head to the weld line, where the tool joints are fused onto the ends.
To survive the rigors of drilling – as well as the numerous cycles of tightening and loosening the threads – the welded area is then heat-treated to make those sections even stronger than the body of the hard-steel pipe. After the weld area is machined, it must pass inspection for any flaws. Only then is it ready for shipment.
Need for Synchronization
In 2009, the weld line was producing just 35 finished drill pipe per shift instead of the expected 100-plus. This was mainly due to the controls architecture which was inefficient, labor-intensive and plagued with downtime.
“The material-handling system used to move the mother pipes into position on the welding line was a complete mess,” recalled Joe Klun, who at the time had recently been hired as engineering and technical manager at Vallourec Drilling Products. “Equipment repeatability was the main problem.”
The plant used ultrasonic sensors on the pick arms that lifted the pipes from outdoor storage and placed them on racks that convey them to the industrial machines inside. The sensors were supposed to precisely position the steel pipe on rollers that moved them into the chucks, which grips the tubes inside the welding machine.
“The conveyor needs to move to a certain height,” Klun explained. “Then it needs to roll into a certain position. After that, it needs to stop. All these things need to happen in sequential steps.”
But that synchronization wasn’t happening. A lack of control over the positioning process hampered throughput and productivity.
“First and foremost, there were 19 PLCs (programmable logic controllers) on the weld line,” Klun explained. “The response time required just for the electronics to talk to each other created a position error of three-quarters of an inch, plus or minus.”
That was compounded by the effect of outdoor light and moisture on the ultrasonic sensors. On a cloudy day, for instance, the sensors would respond differently than on a clear day.
Klun explained the cumulative result. “When a pipe came in, the machine really didn’t even know the pipe was there. There was no handshake between the machine saying, ‘Yes, I’m here, you can start, I’m in the right position.’ Pipes would over-shoot or under-shoot the lift position. We had pipe flipping up. Or pipe would run into the equipment because it wasn’t at the right height.”
Fixing this daily problem was a labor-intensive process.
“We had 12 ultrasonic sensors on each rack. Each one had to be set individually to the same height, using an overhead crane to reposition pipe,” Klun recalled. “So we were only running at about 30 to 35 percent efficiency.”
Blueprint for Control
For a permanent solution, Vallourec realized it needed outside expertise.
“Nobody in the plant fully understood why these ultrasonic sensors were giving us such a hard time. And nobody had looked at the whole circuit,” Klun recalled. “That’s why I called JR Controls.”
Before becoming engineering manager at Vallourec Drilling Products, Klun worked in the automotive industry. That’s where he got to know the system integrators from JR Controls. The company – a Rockwell Automation Recognized System Integrator – has specialized in material-handling controls since 1984.
Klun also was very familiar with Rockwell Automation technology. “I’ve been using Allen-Bradley products for God knows how long,” he said.
At Klun’s request, JR Controls’ experts quickly arrived in Houston to analyze Vallourec’s production problems. Collaborating closely with Klun, they then designed a new controls platform for the line, and engineered a programming blueprint tailored to address its particular issues.
To implement the solution, JR Controls specified a suite of Rockwell Automation hardware and software. The Logix control platform formed the foundation of the new system.
“We replaced 19 PLCs with one master Allen-Bradley ControlLogix® control system, creating tight integration between the programming software, controller and I/O modules,” Klun said. “JR Controls then installed remote racks in cabinets on the floor and connected everything with Ethernet I/O. Now that the system is networked, we have one point to plug into. And I can access the entire line from one spot.”
Operators on the floor also gained unprecedented visibility and control of the welding process after 16 new Allen-Bradley PanelView operator terminals were installed at stations on the line. Previously, these controls were manual push button boxes which provided no feedback to the operators. Through the use of the PanelView capabilities we were able to integrate the push button boxes into the PanelView and then provide feedback letting the operators know if things were okay or not.
The new control platform and the customized programming concept were augmented by a synchronized combination of advanced proximity sensors from Rockwell Automation, replacing the old ultrasonic type.
With the expansive memory of ControlLogix controllers, the plant was able to store and retrieve recipes for each size pipe for the first time.
“The values of all the position sensors are saved. So when we do a changeover, we just call up the size we’re going to run and all the registers change,” Klun said. “Now we don’t have to re-zero and reset everything up, and put a new value in manually.”
The automated precision enabled by the new control platform and specialized programming has significantly increased production on the line.
“We went from only being able to run 35 drill pipes per shift to 110 per shift,” Klun said. “We basically tripled the output of this line, just by doing this project with JR Controls and Rockwell Automation.”
Another time and money saver: The ability to changeover on the fly.
“It used to take us about four hours to make a switch, maybe even six,” Klun said. “Now, we do a changeover in 30 minutes. And most of that time is setting up the clamps on the welder.”
The new controls system also is easy to operate and troubleshoot. Klun especially appreciates the timing function within the programming logic of the Logix platform – and JR Controls’ expertise in deploying the advanced capability to cure glitches on the welding line.
“Their programs are so easy to follow because of the way they apply step logic,” Klun said. “If a fault occurs on the line, we can simply track back through the sequential steps in the process to identify it. Then we can go directly to the source.”
Once the problem is solved, the new control system enables operators to pick up a program exactly where it stopped.
With the significant increase in production on the first welding line, Vallourec Drilling Products has decided it doesn’t need to overhaul the second line – for now.