A subsea pipeline that’s “piggable” is considered a positive. That means a pig, a tool sent through a pipeline to inspect or clean it, or in some cases to separate fluids, can get into the line.But not all lines are piggable, usually either because of their sizes or because they weren’t built to accommodate a pig launcher or receiver.
Pipe inspection remains one of the top priorities in terms of operators looking at asset integrity management. In a recent survey by the Pipe Tech Global Summit – and featured in the April edition of InnovOil – 25% of respondents identified corrosion as the primary cause of pipeline failure. Others drew attention to the importance of new innovations for the inspection of un-piggable pipelines.
As a result, inspection tools are rising to the challenge, and with more flexibility and capability than ever before. Oceaneering’s Magna Subsea Inspection System is one such innovation, recently recognised by the 2015 Offshore Technology Conference (OTC), at which the system won a Spotlight on New Technology Award.
Oceaneering’s Magna Subsea Inspection System, a remotely operated vehicle-deployed, self-propelled inspection tool that uses electromagnetic acoustic transducers, or EMATs, to inspect pipelines from outside, in as much as 10,000 feet of water.
The Oceaneering Magna Subsea Inspection System? (Magna Scan) was selected based on its innovative technology, broad appeal to the industry, proven capabilities through full-scale application, and significant impact with benefits beyond existing technologies.
Enter Magna Scan
The Magna Scan is an ROV-deployable pipeline scanner, combining Oceaneering’s automated Sea Turtle? scanner with other proprietary ultrasonic scanning technology. It can be deployed from any ROV capable of providing the power and communication link required.
It allows operators to inspect and monitor assets – even un-piggable lines – at rapid speed, without halting or disrupting production – all in a single trip.
The Magna Scan identifies localized defects and general wall loss by optimizing ultrasonic techniques including lamb and shear horizontal guided wave capabilities. By combining Oceaneering’s automated scanner known as the Sea Turtle? with proprietary ultrasonic sensors, the system is capable of detecting internal and external damage mechanism including corrosion, isolated pitting, cracking and other potential anomalies. This innovative system safely assists in preventing any catastrophic disasters that may be caused by damage mechanisms in subsea piping resulting in the release of product into the environment.
“The entire system is usually deployed from topside, either held in the ROV manipulator or in a basket attached to the ROV. When the inspection site is reached, the ROV places the Sea Turtle on top of the pipe to be inspected, and the scanner is retained by its magnetic wheels,” Oceaneering senior inspection engineer, Donald McNicol explained to InnovOil. The ROV then pulls back, and observation of the inspection progress is carried out using the ROV’s camera systems. As the Sea Turtle is tethered to the host ROV, the vehicle maintains position as the Sea Turtle is driven along the top of the pipe, under the control of an operator in the ROV control room.
The Magna Scan is a versatile screening tool that assesses the mechanical integrity of assets at a high rate of speed without disrupting production. Additionally, the system only requires clean surface access from the top portion of subsea assets. The advanced system is ROV-deployable, inspects volumetrically 360° around the pipe, and provides real-time data of the wall condition within a single deployment.
The system inspects 360° around the pipe, providing real-time data on the wall condition of ferrous and non-ferrous structures. Magna Scan works on pipelines of up to 4-inch (101.6-mm) diameter, on thicknesses of 0.062-1.125 inches (1.5-28.57 mm), and through coatings of up to 0.070 inch (1.77 mm).
Ultrasonic scanning – including lamb and shear horizontal guided waves – detects wall loss and defects in the pipe, including corrosion, isolated pitting, cracking and other potential anomalies.
The use of the Sea Turtle scanning unit, in combination with a larger ROV, means the speed of data gathering is a major differentiator. The system scans at around 6 inches per second (just under 10 metres per minute), based on operations of around 1,000 feet (300 metres) per day.
“The data set is presented in a number of ways, with the most basic of which include the amplitude and time of flight of the signal. This basic data is also integrated to show change in amplitude and time of flight, so that variations caused by anomalies can be quickly and simply identified, along with the location,” McNicol says. There are additional data display modes, the selection of which is dictated by the particular application, geometry and material being inspected.
Features
As an innovative screening tool, the Magna Scan only requires clean surface access from the top portion of subsea assets.
1.High speed ultrasonic scanning.
2.Able to inspect un-piggable assets.
3.Detects anomalies 360° around the pipe.
4.Identifies localized defects and general wall loss by optimizing ultrasonic techniques including lamb and shear horizontal guided wave capabilities.
5.Combined with Oceaneering’s automated scanner known as the Sea Turtle? with our proprietary ultrasonic sensors, the system is capable of detecting internal and external damage mechanism including corrosion, isolated pitting, cracking and other potential anomalies.
6.Safely assists in preventing any catastrophic disasters that may be caused by damage mechanisms in subsea piping resulting in the release of product into the environment.
Technical data
Diameter range: 4 in-plate.
Electronics temperature: 32 to 122?F.
Sensor temperature: 0 to 250?F.
Speed of measurement: 6 in per/sec.
Wall thickness range: 0.062 in-1.125 in.
Coating thickness: 0.070 in.
Pipe supports per day: n/a.
Length of pipe per day: +1,000 ft.
Note: Magna Scan can be used on Ferrous & Non-ferrous materials.
Conclusion
With the development of multiple technologies, the Magna Scan is the first of its kind providing numerous advantages compared to traditional subsea inspection methods. Prior to the development of the Magna Scan, conventional UT methods have been the primary inspection technique optimized by the industry for online assets.
“It’s basically an external pipe pig,”said Mark Adams, subsea asset integrity manager for Oceaneering. “It detects corrosion, cracking and pitting, which is microbiological-induced corrosion, like bugs.”
Aging pipelines have historically been more prone to bugs, which eat into the pipe like a tiny drill, but more and more modern lines are at risk, too.
“We’re producing a lot of water with our oil,” Adams said. “Before it was just oil. Now we use a lot of water injection to push the oil up, and we also re-inject. The water gets these little bugs in it.”
Adams developed what would become Magna Scan back in 1993, but it wasn’t until much later that a friend cued him into the untouched market of subsea pipeline inspecting. By 2013, he had his first prototype, and the next year saw the sale of his company to Oceaneering, five successful commercial Magna Scan deployments, and three more on tap this year. Five Magna Scan systems in operation and two more on the way.
“We’re going to improve it to do more,” he said. “We’re going to make it do flaw-sizing, so it measures the exact size of the flaw.”
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