In a recent post we discussed a few advantages of digital radiography for nondestructive testing. There are, however, several benefits to transitioning to digital radiography for corrosion inspection from traditional film radiography, particularly improved safety during testing, instantaneous feedback and new possibilities for inspection.
The traditional use of film-based radiography brings with it a number of safety concerns, including:
- High doses of radiation in the plant.
- Maintenance of a large restricted area during the use of film-based radiography equipment.
- The stoppage of work due to film-based radiography equipment use and the costs associated with that downtime.
Converting to digital radiography essentially eliminates those concerns. In many cases pulse type x-ray units can eliminate isotope utilization. Lower curie sources and iridium are used as opposed to cobalt when testing heavy items. Implementing a digital radiography approach limits exposure time to 10 to 45 seconds (conforming to As Low As Reasonably Achievable – ALARA – standards.)
Consider a facility that has several leaks, cracks and corrosion on 16 inch pipes. The use of film or computed radiography (CR) only allows workers to conduct three to five inspections per day without exceeding the exposure limits allowed per hour. Leveraging a digital radiography approach reduces exposure time to 30 seconds per inspection, greatly reducing exposure to plant workers. An easy rule of thumb to remember – one minute film shot equals a 40 second CR shot equals six seconds of a digital radiography shot.
With digital radiography, the instant display of the radiograph at the point of inspection makes the need for re-shots virtually impossible, eliminating the need for unnecessary exposures. The plant operators now have results almost instantly. In many cases the x-ray image may be viewed in seconds and at remote locations even thousands of miles away. This is similar to doctors sharing patient x-rays and scans in hospitals miles away from one another.
What enables the digital X-ray workflow that addresses lack of industry expertise, geographic challenges, documentation, quality control, and remote collaboration with data integrity is the industry standard DICONDE (non- propriety).
DICONDE is a designated ASTM E2339-04 Standard and stands for:
- D – Digital
- I – Imaging and
- CO – Communication in
- NDE – Nondestructive Evaluation
DICONDE is the backbone of a modern digital radiography workflow and supports full image integrity as well as specific transmission protocols and enables truly global operations and compatibility with other DICONDE devices.
- Data can be readily shared between DICONDE workstations
- Image data can be automatically pushed to multiple workstations
- Data can be automatically pushed during non-peak working hours
- Rhythm and the DICONDE protocol will ensure data-integrity
- Reduction of Level 2 and Level 3 labor required
Example of a global architecture where radiography inspection, image assessment and remote diagnosis are done on different geographic locations
Digital radiography provides new opportunities to inspect and test equipment for damaged mechanisms, particularly due to corrosion and erosion. Operators and asset owners can now conduct inspections of structures that are thicker and more complex in less time and often with lower radiation sources. New technologies and improvements may be used for both in-process inspection as well as new construction. Enhanced image quality is associated with improved measurement capabilities and increased probability of damage detection.
To read more about the benefits of digital radiography, you can find the full article here in Inspectioneering.
By Richard Mills, GE Radiography SME and ASNT Level III