Radiographic Testing (RT) is a nondestructive examination (NDE) technique that involves the use of either x-rays or gamma rays to view the internal structure of a component. In the petrochemical industry, RT is often used to inspect machinery, such as pressure vessels and valves, to detect for flaws. RT is also used to inspect weld repairs.
Compared to other NDE techniques, radiography has several advantages. It is highly reproducible, can be used on a variety of materials, and the data gathered can be stored for later analysis. Radiography is an effective tool that requires very little surface preparation. Moreover, many radiographic systems are portable, which allows for use in the field and at elevated positions.
There are numerous types of RT techniques including conventional radiography and multiple forms digital radiographic testing. Each works slightly differently and has its own set of advantages and disadvantages.
Conventional radiography uses a sensitive film which reacts to the emitted radiation to capture an image of the part being tested. This image can then be examined for evidence of damage or flaws. The biggest limitation to this technique is that films can only be used once and they take a long time to process and interpret.
Unlike conventional radiography, digital radiography doesn’t require film. Instead, it uses a digital detector to display radiographic images on a computer screen almost instantaneously. It allows for a much shorter exposure time so that the images can be interpreted more quickly. Furthermore, the digital images are much higher quality when compared to conventional radiographic images. With the ability to capture highly quality images, the technology can be utilized to identify flaws in a material, foreign objects in a system, examine weld repairs, and inspect for corrosion under insulation.
The four most commonly utilized digital radiography techniques in the oil & gas and chemical processing industries are computed radiography, direct radiography, real-time radiography, and computed tomography.
1) Computed Radiography
Computed radiography (CR) uses a phosphor imaging plate that replaces film in conventional radiography techniques. This technique is much quicker than film radiography but slower than direct radiography. CR requires several extra steps compared to direct radiography. First, it indirectly captures the image of a component on a phosphor plate, then converts the image into a digital signal that can be visualized on a computer monitor. Image quality is fair but can be enhanced using appropriate tools and techniques (i.e, adjusting contrast, brightness, etc. without compromising integrity). It’s important to know how tools, such as adjusting contrast, effect the image. Care should also be taken to make sure minor defects are not hidden after enhancements are made.
2) Direct Radiography
Direct Radiography (DR) is also a form of digital radiography and very similar to computed radiography. The key difference lies in how the image is captured. In DR, a flat panel detector is used to directly capture an image and display that image on a computer screen. Although this technique is fast and produce higher quality images, it is more costly than computed radiography.
3) Real-Time Radiography
Real-time radiography (RTR), like it’s name suggests, is a form of digital radiography that occurs in real time. RTR works by emitting radiation through an object. These rays then interact with either a special phosphor screen or flat panel detector containing micro-electronic sensors. The interaction between the panel and the radiation creates a digital image that can be viewed and analyzed in real time.
The brighter areas on the image are a result of higher levels of radiation that contact the screen. This corresponds to the thinner or less dense section of the component. Conversely, darker areas are a result of less radiation interacting with the screen and indicate where the component is thicker.
Aside from being able to make the images available more quickly and analyze them in real time, RTR has several other advantages. One being that digital images don’t require physical storage space and thus are easier to store, transfer, and archive than film.
On the other hand, this method has several disadvantages as well. Compared to conventional radiography, RTR has a lower contrast sensitivity and limited image resolution. Images created via RTR often suffer from uneven illumination, limited resolution, a lack of sharpness, and noise. These factors have a major impact on image quality.
4) Computed Tomography
Computed tomography (CT) is a technique that takes hundreds to thousands (depending on the size of the component) of 2D radiography scans and superimposes them to create a 3D radiographic image.
In an industrial setting, CT can be achieved in two ways. In one method, the component to be inspected remains stationary while the radiation source and x-ray detector rotate around the component. This technique is more likely to be utilized for large components. The second method consists of the radiation source and x-ray detector remaining stationary while the component is rotated 360 degrees. This second technique is more useful when the component is small or has complex geometry.
Although this technology is timely, expensive, and requires a large amount of data storage, CT provides highly accurate images, is repeatable and reproducible, and minimizes human error.
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Blog
September 13, 2018 By Berg Engineering
Nondestructive testing (NDT) careers are on the rise in today’s economy. These fields are constantly advancing, and there is an ever-growing need for technicians, quality assurance specialists and inspectors as infrastructure in the United States continues to age. |
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July/August 2016 Inspectioneering Journal
By Sanjoy Das at Bhabha Atomic Research Centre, and D. Mukherjee at Bhabha Atomic Research Centre
The structural integrity of components is controlled by material properties, the presence of flaws, and levels of applied stress. Several factors such as temperature, type of loading, toughness, corrosion resistance, micro-structural stability, cost etc. dictate the suitable material for the desired application. |
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Blog
May 4, 2015
Because radiography involves the use of large amounts ionizing radiation, safety is integral for the technician, the public, and the environment. |
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March/April 2015 Inspectioneering Journal
By Ana Benz at IRISNDT, Michael O. Nichols at Marathon Petroleum Company, and Bradley Baudier at Marathon Petroleum Company LP
This article provides a discussion of a recent inspection performed at a U.S. refinery. Industry HF lines are experiencing piping failures in increasing numbers due to the presence of residual elements entrained within their carbon steel components. |
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November/December 2014 Inspectioneering Journal
By Rajesh Bose at BP, and Terry M. Webb at BP
The introduction of PAUT is a challenging effort initially, but can have a very positive impact on your first TAR and become a routine inspection for future TARs. When fully implemented, radiation safety boundaries can be reduced significantly or eliminated altogether. |
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November/December 2014 Inspectioneering Journal
By Kelsey Hevner at Quest Integrity Group
Steam reformers are critical assets for the successful operation of hydrogen, ammonia, and methanol plants. The steam reformer is also one of the most expensive assets in these facilities. Catalyst tubes inside the reformer are one of the most important and costly components. |
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December 15, 2014 By Nick Schmoyer at Inspectioneering
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. |
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November/December 2013 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
Over recent years large strides have been made in application, development, and utilization of Digital Detector Arrays (DDAs) in field radiography environments (an application previously limited to film and computed radiography [CR] techniques). |
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November/December 2013 Inspectioneering Journal
By Jan Verkooijen at TUV Rheinland Sonovation
To understand the current non-destructive testing (NDT) world, it is perhaps a good idea to look back at things historically. By doing this, changes which have taken place become apparent, and very soon one can conclude that this is actually quite significant! |
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September/October 2013 Inspectioneering Journal
By Sanjoy Das at Bhabha Atomic Research Centre, D. Mukherjee at Bhabha Atomic Research Centre, and K.K. Abdulla at Bhabha Atomic Research Centre
The Modulation Transfer Function (MTF) is used in imaging science to assess the reliability of imaging systems to produce different spatial frequency. In digital radiography, it can be used to detect frequency responses of different inspection conditions. |
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January/February 2013 Inspectioneering Journal
By A.C. Gysbers at The Equity Engineering Group, Inc.
This article is the third of a series of articles that will focus on one critical sub process within a PEIP that is key in managing the integrity of process piping: thickness monitoring programs for internal corrosion. These articles will discuss what constitutes an effective piping thickness monitoring process and will present several practices that may be new to some readers, but these practices have produced beneficial results in other major piping reliability programs. |
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November/December 2012 Inspectioneering Journal
By Sanjoy Das at Bhabha Atomic Research Centre, D. Mukherjee at Bhabha Atomic Research Centre, and S. Anantharaman at Bhabha Atomic Research Centre
Radiography technique is one of the most widely utilized non-destructive methods, used in industry to evaluate the structural integrity or find out the hidden details of an assembled structure. Since this method uses ionizing radiation, it is important to ensure not only the quality of product, but also the safety of the technician and the general public, as well as the protection of the environment. |
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May/June 2012 Inspectioneering Journal
By Jason Butz at SAIT Polytechnic
Over the past 100 years, Nondestructive testing has made tremendous advances. New NDT methods have been introduced, while old "tried and true" methods continue to be improved. Although some NDT methods have drastically changed or "evolved" over time, the principle behind each method has remained the same; "To ensure the safety and integrity of manufactured items or goods." |
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November/December 2010 Inspectioneering Journal
By Sanjoy Das at Bhabha Atomic Research Centre, B.K. Shah at BARC, and D. Mukherjee at Bhabha Atomic Research Centre
Rapid industrial and technological growth throughout the world makes it necessary to develop new materials along with advanced Non-Destructive Testing (NDT) Methods to ensure their quality without premature failures. The complex modern system, where materials are required to perform consistently with optimum efficiency, demands stringent quality control of engineered components. |
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July/August 2010 Inspectioneering Journal
By Santhosh Lukose at Metalcare Inspection Services Inc.
CUI (Corrosion Under Insulation) has always been a challenge for plant operators, quality assurance/reliability engineers and equipment owners. It is hard to identify the problem until it has become an emergency situation, often leading to unit shut downs or even the whole facility shut down for emergency repairs. |
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November/December 2008 Inspectioneering Journal
By Charles L. Foster at Pacific Gas & Electric
A picture is worth a thousand words and thousands of dollars. There are many instances where in-service inspection reports are greatly enhanced by including photographic documentation. Using a conventional high quality 35 mm camera requires cumbersome amounts of equipment and consumes a lot of time. Developing film ASAP is an additional trip away from the inspection site and is an immediate necessity to insure picture quality before the area is no longer accessible. The inspector must then paste these acceptable photos onto report pages and make another trip to obtain color copies for the report. |
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July/August 2005 Inspectioneering Journal
By Sanjoy Das at Bhabha Atomic Research Centre, and B.K. Shah at BARC
Radiography is the most widely used volumetric examination technique for non-destructive evaluation of components, as it offers the advantage of direct viewing of the flaw image, judging the type of flaw and provides a permanent record. Flaw characterization methods, described by size, shape & Location, require classification of the type or nature of flaw, position of flaw and flaw severity. Accurate sizing of the flaw to assess its severity is important. ISO Guide 25 "General Requirements for the Competence of Calibration and Testing Laboratories" (1990), requires one to specify the uncertainty of each measurement. In radiography there are several factors which contributes to uncertainty for quantitive measurement. This paper describes a study undertaken to calculate the uncertainty in flaw sizing and to estimate the real size of discontinuities observed in radiography. |
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Partner Content
InVista is a lightweight, hand-held ultrasonic in-line inspection tool (intelligent pig) capable of detecting pipeline wall loss and corrosion in unpiggable or difficult-to-inspect pipelines. The pipeline geometry inspection data captured by the InVista tool is exceptionally powerful when combined with the LifeQuest™ Pipeline fitness-for-service capabilities, providing an integrated solution set for the pipeline industry. |
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March/April 1999 Inspectioneering Journal
By John Reynolds at Intertek
Some Middle Eastern and European operators are now using AE successfully to screen tanks for internal inspection by listening for active tank bottom corrosion, and then grading the tank as high, medium or low need for internal inspection. |
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November/December 1997 Inspectioneering Journal
By Dave Palmbach at DBA Systems, Inc.
Radiographic film provides an inexpensive method of ensuring the quality and structural integrity of construction over time. Much of today's analysis being performed with Non Destructive Test (NDT) radiographic film is done visually using light boxes. |
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September/October 1997 Inspectioneering Journal
By John Reynolds at Intertek
This is the fourth in a series of articles on piping inspection that I'm writing for the Journal. One of the previous ones dealt with improving thickness data taking accuracy with digital ultrasonic methods. This article is a "sister article" that deals with improving the accuracy of profile radiographic inspection techniques, also called isotope radiography, wall shots, or tangential radiographic inspection. |
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September/October 1995 Inspectioneering Journal
By Dr. Nand K. Gupta at Omega International Technology, Inc.
In May 1995, Omega International Technology, Inc., began testing a new system to measure pipe wall thicknesses using digital radiography (RT) scanning. This new system has the potential for being faster, less labor intensive, and shown improved accuracy over traditional ultrasound testing, and at a lower cost. Perhaps best of all, scanning can be performed while the pipe is in service, insulation in place. |
Olympus provides an industry-leading portfolio of remote visual inspection, industrial microscopy, ultrasound, phased array, eddy current, phased array, and optical metrology solutions including: ultrasonic flaw detectors and thickness gages, videoscopes, microscopes, advanced NDT systems, and X-ray fluorescence analyzers.
Olympus provides an industry-leading portfolio of remote visual inspection, industrial microscopy, ultrasound, phased array, eddy current, phased array, and optical metrology solutions including: ultrasonic flaw detectors and thickness gages, videoscopes, microscopes, advanced NDT systems, and X-ray fluorescence analyzers.
Sentinel Integrity Solutions is a full service inspection company, providing a full suite of inspection support to service the Petroleum (upstream, midstream and downstream operations), Chemical, Power and Pipeline Industries. We are respected by our clients for the unsurpassed reliability, dedication and professionalism exhibited by our personnel and the customer service and responsiveness exhibited by our Management Team.
Sentinel Integrity Solutions is a full service inspection company, providing a full suite of inspection support to service the Petroleum (upstream, midstream and downstream operations), Chemical, Power and Pipeline Industries. We are respected by our clients for the unsurpassed reliability, dedication and professionalism exhibited by our personnel and the customer service and responsiveness exhibited by our Management Team.
PK Technology is a full-service inspection contractor, as well as, an in-house software development company specializing in the Oil and Gas industry. PK Technology is the creator of intelliSPEC, the worlds first Digital Data Management System (DDMS) which is a robust and intelligent solution designed to digitize, analyze and realize all vital data.
PK Technology is a full-service inspection contractor, as well as, an in-house software development company specializing in the Oil and Gas industry. PK Technology is the creator of intelliSPEC, the worlds first Digital Data Management System (DDMS) which is a robust and intelligent solution designed to digitize, analyze and realize all vital data.
Pro-Surve Technical with subsidiaries ProSource Radiography and ProForce Industrial are an integrated inspection, NDT, reliability engineering, Data management and project controls service provider assisting clients across CapEx/OpEx budgeted projects processes. We concentrate on solutions provided by the integration of engineering and inspection.
Pro-Surve Technical with subsidiaries ProSource Radiography and ProForce Industrial are an integrated inspection, NDT, reliability engineering, Data management and project controls service provider assisting clients across CapEx/OpEx budgeted projects processes. We concentrate on solutions provided by the integration of engineering and inspection.
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Pinnacle Advanced Reliability Technologies (PinnacleART) is a leader in building, implementing and maintaining comprehensive reliability programs for facilities in the oil and gas, chemical, mining, pharmaceutical, wastewater and electric power industries, to name a few. Our team consists of talented experts and engineers, who offer the highest degree of service and uncompromised reliability for every one of our projects. PinnacleART’s specialists are dedicated to delivering optimal outcomes for our clients, which results in reducing risk, ensuring compliance, optimizing costs and improving safety.
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Asset Intelligence Report
This Asset Intelligence Report on Conventional NDE provides an introduction to Conventional NDE and its applications across industries and equipment lifecycles. |
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Press Release
Intertek Group plc, November 19, 2013
Intertek Group plc (Intertek), the leading international provider of quality and safety services to a wide range of industries, announces that it has acquired Global X-Ray & Testing Corporation (GXT), a leading provider of non-destructive testing (NDT) services to the oil and gas industries. |
