This post is based on an article from the December/November 2013 issue of Inspectioneering Journal by Richard Mills at GE, John T. Iman at GE Oil and Gas Measurement & Controls-Inspection Technology, and Martin Sauerschnig at GE Oil and Gas Measurement and Control. You can find the original article here.
The oil and gas market has used X-ray inspection to improve the quality of products and services for more than 100 years, dating back to the discovery of X-rays in 1895 by Wilhelm Conrad Roentgen and radium in 1898 by Marie and Pierre Curie. Due to constant innovation in techniques and technologies, X-ray continues to play a crucial role in the industry for determining the integrity of welds, structures, and overall asset conditions.
The adoption of X-ray inspection by the oil & gas market led to the development and use of various non-destructive testing (NDT) techniques. The innovation for field use of X-ray continues to evolve and improve for the oil and gas sector as the need for clear, accurate images of difficult to access or highly-sensitive areas in equipment continues to foster innovation applications to x-ray, particularly when it comes to accessing (imaging) and measurement of localized forms of corrosion and other damage mechanisms.
Over recent years large strides have been made in application, development, and utilization of Digital Detector Arrays (DDAs) in field radiography environments. The use of industrial digital radiography shows benefits of significantly reduced exposure times versus traditional film and computed radiography techniques. These results were made possible by technology investments with a focus on image quality at lower radioactive exposure dosage.
Application development efforts have included, and have been successfully implemented in, a wide range of field cases for the oil and gas industry. Significant reductions in exposure times have been realized in this industry, with better image quality. The reduction in exposure time not only enables productivity through shorter shot times and the instant availability of images for review and analysis, but also improves overall safety for radiation workers and other employees.
Applications of Interest
The digital detector technology can be used for many oil and gas applications and particularly complements the Small Controlled Area Radiography (SCAR) system, low strength isotopes, constant potential X-ray generator, and even “Pulsed” X-ray cameras to provide safe, rapid, and environmentally friendly inspection options.
Assessing Damage Mechanisms
In the oil and gas industry for example, the emphasis for radiography with conventional film has changed from detecting flaws arising as a result of the welding process, to process-induced flaws and other issues. Workers must accurately measure remaining wall thickness, often through coatings, wrapped repairs and insulation, and while on-stream through process fluids.
One damage mechanism that continues to plague the oil and gas and power generation industries is erosion/corrosion. Routine inspections for corrosion are essential to ensure the asset health of the pipes, valves and other equipment used in the oil & gas industry. Unseen corrosion, such as that occurring inside a pipe, is the most dangerous and can cause the most damage, leaks and spills, and it underscores the importance of inspections and early detection.
Simply visually inspecting the equipment is not enough, especially if the inspection methods and tools themselves can cause further harm. Companies should consider employing non-destructive testing (NDT) methods, such as digital radiography, to get a clear, safe, non-damage causing assessment of the health of their equipment.
Radiography for Corrosion Inspection
Radiography is a NDT method that can be used to evaluate the integrity of a specimen. Routine radiography inspections of pipelines and valves allow inspectors to identify early signs of metal loss and points of weakness in the equipment. Continued and advancing X-ray technologies with specific techniques and measurement capabilities enable new capabilities that were not practical, or were a safety concern, with film-based radiography or even computed radiography. A new innovative milestone, the use of Digital Detector Arrays (DDA) for digital radiography, is rapidly being adopted in the oil and gas industry. With the development of new electronic, highly portable or even wireless digital detectors, radiography has grown in its effectiveness for many plants and field inspections and provides many benefits for productivity.
The conversion from film to digital radiography has been gradual. Although codes do accept digital radiography, oftentimes asset owners are hesitant to change their procedures, leading them to continue using what they know works and what their teams are comfortable using and missing the opportunities to realize the benefits new technology affords.
Conlusion
There are several benefits to transitioning to digital radiography for corrosion inspection, particularly improved safety during testing, instantaneous feedback, new possibilities for inspection, cost savings, image quality, and the adoption of green-friendly techniques.
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