T9074-AS-GIB-010/271 Rev 1
APPENDIX A COMPUTED RADIOGRAPHY REQUIREMENTS FOR THE DETECTION AND MEASUREMENT OF PIPE CORROSION AND EROSION
A.1 SCOPE. This appendix provides requirements for the use of computed radiography (CR) to detect and measure corrosion and erosion in pipe and piping system components. The requirements are applicable to both insulated and non-insulated pipe. These requirements are applicable to the use of tangential side wall techniques to measure remaining pipe wall thickness. The use of pixel intensity based techniques (such as contact shots on large diameter heavy wall thickness pipe) to measure pipe wall thickness shall not be performed to generate a quantified wall thickness measurement. Pixel intensity may be used to qualitatively identify where additional tangential exposures should be acquired. A.1.1 Supplemental Requirements. The requirements in this appendix are supplements to the film based radiography requirements in Chapter 3. All requirements in Chapters 1 - 3 are invoked for compliance unless otherwise revised or addressed in this appendix. A.1.2 CR Guidance/Tutorial/Definitions. ASTM E2007 includes useful definitions, tutorial and guidance on the CR process and may be used as a guide in the establishment of the inspection activity’s process, training program, and procedure. A.1.3 CR Limitations. The techniques developed in accordance with this supplement shall not be applied if localized pitting or material loss prevents clear identification of the ID/OD boundary. The qualification report shall identify under what conditions the measurement is valid (e.g., filled or unfilled piping). A.2 INSPECTION PROCEDURE. All inspections shall be performed in accordance with a written procedure that meets the procedure requirements of Chapters 1 - 3. In addition to the radiographic testing procedure requirements in Chapter 3, the CR procedure shall also include the following: a. CR system manufacturer/model. b. CR system maximum resolution (pixels/mm). c. CR scanner gain and data mapping settings. d. Acquisition/processing/analysis software identification and version. e. Inspection monitor manufacturer/model, display format, pixel pitch, and diagonal view dimensions. f. Display bit depth, gray mapping type, limits, and allowable inspector adjustments. g. Background illumination requirements for electronic viewing area. h. Imaging plate manufacturer and series. i. Filter and screen materials, thicknesses, and placement (e.g., source outlet, outside cassette, inside cassette). j. Digital image processing methods and analysis techniques employed. k. Requirements to determine if sufficient contrast exists at edge of pipe wall. l. Requirements to determine if reference standard is properly located and oriented. m. Minimum exposure and/or minimum pixel value requirements. n. Digital image file requirements and requirement to convert file to Digital Imaging and Communications in Medicine (DICOM) or Digital Imaging and Communications in Nondestructive Evaluation (DICONDE).
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