Digital Radiography- An Alternative to Film Radiography
Project Participants: Northrop Grumman Shipbuilding- Newport News
Project Start: November 2004
The current film-based radiographic inspection process uses expensive, non-reusable film and chemicals that contain materials (silver) that are potentially hazardous to the environment and wastes thousands of gallons of water every year. This film-based inspection process is also very cycle-time intensive, requiring manual handling of materials throughout the entire process.
This project successfully used commercially available computed radiography (CR) equipment to extend current technology and develop processes and standards to replace the film-based process in critical naval applications. Northrop Grumman Shipbuilding-Newport News (NGSB-NN) identified and acquired state-of-the-art CR capabilities, knowledge and supporting technical resources that are being tested in a practical shipyard environment to assess overall potential benefit.
Project results are having an impact beyond naval construction. Considerable progress has been made toward industry-wide acceptance by pursuing standardization through the American Society for Testing and Materials (ASTM). In a parallel effort, the NGSB-NN Principle Investigator developed ASTM E-746 “Standard Practice for Determining Relative Image Quality Response of Industrial Imaging Systems.” ASTM has approved this document and will publish it in their International Book of Standards. Major revisions to the ASTM E-2007 “Standard Guide for Computed Radiography” were also submitted and are awaiting final approval.
NGSB-NN continues to evaluate the ability of CR technology to provide equivalent or improved image qualities, area-of-interest coverage and discontinuity detection when compared to current methods. Finally, all naval CR standards and training materials will be updated to incorporate the latest technology refinements for weld and casting inspections as the team continues to seek approval of ASTM E-2033 “Standard Practice for Computed Radiography”.
The NGSB-NN team is currently pursuing a follow-on project with CNST that will lead to full implementation of Computed Radiography technology by ascertaining inspection confidence with isotopes and high energy applications in addition to resolving technical and implementation issues.