NDT Shaves Days Off BOP Inspection Time
A fingerprint’s beauty is found in its uniqueness. In each arch, loop and whorl of the print, lie the identifying characteristics that set one person apart from another. Machines also bear similar telltale marks of individuality. So do the bolts, flanges, nuts and studs holding those machines together. But short of cracking open its exterior, how can one visually inspect the condition of a machine’s interior components?
One way is through nondestructive testing (NDT) to ensure all components of a system are functioning in a reliable and cost-effective manner. In 2015 Baker Hughes, a GE company (BHGE), formerly GE Oil & Gas, piloted its NDT BOP Inspection Technology System that leveraged 4-D scanning using digital fingerprinting to deliver rig-based inspection and recertification of BOPs without disassembly.
Using robotics, analytics and phased array ultrasonic testing, periodic inspections create a 4-D comparison of BOP components. The fingerprint becomes the baseline for equipment condition at any point in its life cycle. By digitally comparing the current scan against previous scans, changes are highlighted and mapped. The system has been used with several customers, including four BOP stacks for Diamond Offshore as part of the contractual services agreement the companies entered into in 2016.
Enhancements made to the system since the start of the pilot program include the ability to see the individual threads of the bolts, nuts and studs securing flanges.
“You’ve got a stud coming through a flange with a nut sitting on top of it,” said Dave Bowen, product leader for digital and services for BHGE’s drilling systems business. “The moment you release that nut, you’re taking pressure off the system and changing the dynamics of what’s happening to that seal. We developed a technology that gives us the ability to put a scanning device over a nut, stud or bolt and see the threads to determine if there are any issues that would lead us to believe that the part is nearing the end of its life.”
He continued, “Performing an inspection on the fasteners within a BOP stack—nominally 500 to 600 per stack—typically takes 30 minutes to an hour per fastener. With digital fingerprinting that inspection time reduces to about two minutes per bolt,” which he said is “a radical change and one that delivers huge savings to our customers.”
In addition to time savings, scanning the equipment is a far safer process than breaking down and inspecting the components. It takes a day for the technicians to set up the equipment, with the scanning occurring on the second day, according to Bowen. Depending on the component being inspected, the entire process would take six to seven days.
“We estimate there’s a 40% savings just in the time to do the inspection itself,” he said. “But what it doesn’t calculate—which is going to be just very dependent rig to rig—is the amount of time it takes to go break down a BOP in a confined space and in a very tough environment. It represents a big safety hazard to the individuals at work. It also represents the opportunity for significant damage to that equipment that can occur from disassembling and reinstalling.”
Taking everything apart and inspecting can take 30 to 40 days versus a week if the scan is done in situ using the digital fingerprinting technology, Bowen said. “The safety and time savings makes the benefits of the in situ inspection solution almost incalculable.”
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