The quarterly newsletter from Phoenix National Laboratories that focuses on quality, testing technology, and inspection trends
PNL is providing expanded Computed Radiography (CR) capabilities to keep pace with advances in nondestructive technology and protect our environment. CR does not use hazardous chemicals or disposable film like traditional film radiography thereby minimizing the hazardous waste generated. Technologically, CR offers many advantages over conventional film techniques. The three main advantages are: No need for photo sensitive rooms to process film, the absence of chemicals to monitor or dispose of, and easy file sharing for end users in a distribution group; the process creates multiple sets of one shot instead of numerous images.
PNL currently has six CR units that can be used in mobile trucks or set up in any convenient location on a job site or in a laboratory. We continue to provide conventional film radiography for those cases where it is required or needed. PNL is committed to evolving and growing as additional codes and technologies emerge.
Computed Radiography (CR) Project Illustrations
The current water shortages emerging in the booming southwestern United States have prompted the necessity for engineering solutions to transport water from one region to another. These future projects will require nondestructive testing, including CR (Computed Radiography), that PNL provides for pipeline weld joint testing during the pipeline erection process. There are two projects currently in the developmental stages shown below.
Actual CR weld image
Puerto Peñasco’s desalination project conveying water from Mexico’s Sea of Cortez, and delivering potable water to Buckeye, Arizona via pipeline.
US Army Corps of Engineers’ construction of an aqueduct from the Old River Control Structure on the Mississippi River, carrying it to Lake Powell in Utah and Arizona, then supplying more water down the Colorado River to fill Lake Mead in Nevada.
Northern Arizona is prone to extreme winter conditions and can be very treacherous for workers at outdoor sites. If you are traveling to northern Arizona, for work, it is important to follow the Arizona Department of Public Safety alerts. The National Weather Service issues several types of advisories for winter weather conditions. Understanding the differences between the three notifications is crucial throughout the winter season. A winter storm ‘advisory’ indicates that wintery weather is expected and advises exercising caution- light amounts of snow precipitation or blowing snow will cause slick conditions. The second, winter storm ‘watch’ means to be prepared; a winter storm could produce heavy snow, sleet or freezing rain. Drive carefully in mountainous areas avoiding cruise control functions. The third is the winter storm ‘warning’ indicating taking action-snow, sleet or ice is expected, causing significant impact including car accidents and injuries from slips, trips and falls.
On December 23, 2022, a 22-year-old woman in Buffalo, New York, died after being trapped in her car for 18 hours during a lethal blizzard.
OSHA guidelines assign the employer to provide recommendations to their employees regarding work-site safety planning. These suggestions include keeping extra clothing handy in case workers get wet, having warm sweetened liquids, PPE, water repellent outer wear, thermal under garments, insulated headgear and foot wear, gloves, and garment closures that retain warmth. Prepare your vehicle by checking tires, wipers, and wiper fluid. One should equip their vehicles with shovels, ice scrapers, sand, blankets, cell phone and charger, road map, safety flairs, first aid kit, water, flashlight with extra batteries, and non-perishable snacks. By comprehending the three winter advisory alerts, and preparing your vehicle and work clothing accordingly, you will be prepared for the upcoming Arizona winter conditions.
Arizona wintry worksite
William Roentgen was the German physicist, mechanical engineer, and professor who accidentally discovered X-rays in 1895. While he was conducting an experiment with glass tubes, he noticed photographic plates near his equipment were glowing. He discovered the glowing was caused by ‘mysterious’ rays emitted by the glass tube used in his investigation.
Historically, the discovery of the traditional X-ray laid the groundwork for the future of Computed Radiography (CR). In 1980 Computed Radiography officially joined the formal medical diagnostic landscape. Nondestructive testing of welds and components was later developed as a consequence of the radiography application for medical diagnostics.
The radiography utilized in nondestructive testing (NDT), has traditionally used an analog image (film/radiograph). Now technicians can use a reusable phosphor image plate to capture images that is termed Computed Radiography (CR). This method of inspection has many inherent challenges that radiographers must be aware of, and if not addressed properly, can be detrimental to the overall inspection results. For this reason, generation and evaluation of computed images requires additional training, over and above current requirements found in SNT-TC-1A, NAS 410 and CP-189 for conventional radiography. PNL provides this training to our technicians making them well versed and capable of producing code quality computed images.
CR, as defined by ASTM E1316 (photo stimulated luminescence method), is a two-step radiographic imaging process. First, a reusable storage phosphor imaging plate is exposed to ionizing radiation. Second, the luminescence from the plate’s photostimulable luminescent phosphor is detected, digitized and presented on a high-resolution computer screen.
Managing this process, with the objective of achieving the optimum digital image, is the challenge faced by radiographic practitioners. The overall success is based on the digital image acquisition system utilized, and variables that are consistent with typical radiographic conditions. PNL utilizes Virtual Media Images (VMI) scanners along with Starrview software to create and process images. In our opinion, the VMI 16-bit system, which generates images with 65,536 shades of gray, is one of the best systems for industrial radiography and offers the most user defined flexibility.
Implementing CR begins with a fundamental understanding of the radiographic principles that have been practiced for decades with film radiography and commissioned by the aerospace, automotive, construction, energy, oil and gas, and shipping industries. Certified radiographers are required to understand these principles, along with specific knowledge in the manufacturing and fabrication process to correctly interpret the acquired digital image. PNL’s technicians are well trained in the basic principles of radiography as well as the additional computed technology needed to produce consistent high-quality images.
VMI Model 5100 portable CR equipment can be placed in any milieu
Due to our current extreme workload, our team was unable to produce a Tech Talk video for this Quality Examiner feature. We take this opportunity to recognize the industrious work of Zander Zuran, CWI, Radiographer Level II. He is an invaluable asset to our organization, and we acknowledge his knowledge, integrity and flexibility, as an expert in conventional and CR (Computed Radiography). Zander has been working at PNL for ten years.
Zander Zuran, CWI, Radiographer Level II
One of the driving forces behind computed radiography usage has been the ASME Boiler and Pressure Vessel Code (B&PVC) committee for Nondestructive Examination (NDE). Section V, Article 1 of the B&PVC details the certification requirements for personnel while Article 2 provides the technical variable rules for making standardized radiographs. Referencing code sections, such as ASME B31.3 - Process Piping, require radiography to be performed in accordance with the Section V, Article 2 of the B&PVC. Mandatory Appendix VIII of Article 2 details the additional rules for using phosphor image plates to create radiographs.
As with all NDE written procedures are required. In addition to conventional radiography, when using phosphor imaging plates some additional information is required to be detailed. This includes:
Additionally, radiographic technique details for each computed radiograph must include the equipment manufacturer, model, and serial number of the specific image acquisition unit used; the imaging software version and revision, and the numerical values of the final image processing parameters, to include filters, window (contrast), and level (brightness).
Because the contrast/brightness of an image can be adjusted, it is important to only evaluate acceptance of the weld or casting quality within the range of contrast/brightness that demonstrates the required IQI sensitivity. We have occasionally seen where an untrained technician will adjust the window and leveling to show the IQI only to have the weld totally obscured and then make the interpretation using different settings that doesn’t show the IQI and leads to an incorrect interpretation. When this happens it is primarily because of poor technique and/or improper selection or placement of the IQI.
One of the advantages of using computed radiography for process piping is that internal concavity (suckback) can easily be measured using intensity values at points as small as a 50-micron pixel. While that is not very practical, it is usually best to average the intensity over a 10- or 50-pixel area to make more accurate comparisons, which most software allows.
Another advantage is that the images are more easily shared so the interpretations can be discussed and verified. We find this to be extremely helpful for our technicians and clients to be able to get a second opinion in a timely manner without having to transport film or personnel to different locations.
To see a full list of our radiography services, click below to find out more.
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