READING THE RADIOGRAPHS DETERMINE THE QUALITY ANALYZE THE IMAGE REPORT THE RESULT Is the penetrameter (IQI): a. the proper one; b. positioned properly; c. clearly visible including the required hole, or wire. Fig. 1 — A systematic approach to reading radiographs. Inspection Trends / Spring 2011 19 Nonrelevant Indication. An indication caused by the test object geometry or other condition that does not require evaluation (e.g., an indication of incomplete penetration appearing on the radiograph of a weld that by design is a partial penetration weld). Relevant Indication. An indication caused by a discontinuity or a condition that requires evaluation. Discontinuity. An intentional or unintentional interruption in the physical structure or configuration of a material or component. All indications of discontinuities (relevant indications) require evaluation. Evaluation. A review, following interpretation of an indication, to determine whether or not a relevant indication meets the acceptance criteria. Following this review, the indication must be dispositioned as either acceptable or not acceptable. Due to the diversity of requirements of various industry standards, we do not have uniform acceptance criteria. Therefore, it is important that the RI review the acceptance criteria of the applicable code prior to making any evaluation of discontinuities. Defect. One or more discontinuities whose aggregate size, shape, number, orientation, location, or properties do not meet the specified acceptance criteria and are cause for rejection. False Indications (Film Artifacts) Improper processing techniques or careless handling of the film during its loading and unloading from the cassette are the usual causes of false indications, normally referred to as film artifacts. Occasionally, film artifacts may be due to manufacturing defects in the film. Film artifacts can often easily be distinguished from true indications; however, some may have an appearance similar to a discontinuity and may lead to a misinterpretation. Taking the radiograph off of the viewer and looking at both sides under reflected light will often verify that an indication is a film artifact. Sometimes another exposure of the same area, using different lead screens and a different cassette, is necessary to determine if an indication on the original radiograph was a film artifact or an indication of a discontinuity. False indications are not predictable and not repeatable when the original radiograph is reshot. Most codes and specifications will not permit an artifact in the area of interest if, in the opinion of the RI, it might be confused with the indication of a discontinuity, may mask the indication of a discontinuity, or in any way interferes with interpretation of the radiograph. Artifacts Occurring before Processing Radiation fog occurs when the film is stored too close to a source of radiation, or when a film is inadvertently left in the exposure area during the exposure of another film. Light fog is caused by storage of film in a faulty storage box or bin, leaving the lid off the box, exposure to white light in a faulty darkroom, the use of the wrong type of safelight, too strong a bulb in the safelight, or to the use of a faulty film holder. It is usually local, but may be an overall fog. Crimp marks occur when the film is allowed to bend abruptly during the loading and unloading of the cassette. If the crimp occurs during loading of the film into the cassette (i.e., prior to exposure), the crimp mark will appear light. Dark crimp marks occur after exposure while unloading the film from the cassette prior to processing. Scratch marks may be caused by a fingernail or rough handling of the film while loading or unloading the cassette. Scratches are easily identified by holding the processed film on an Is the radiograph properly identified? Is the film density within the required range? Was the required coverage achieved? Verified by location markers. Was film processing adequate? Are radiographs free of artifacts in the area of interest? Interpretation and Classification of Indications False Indications Nonrelevant Indications True Indications False Indications Do any film artifacts in the area of interest interfere in any way with the interpretation of the radiograph? True Indications – Discontinuities Identify type Measure size Count number Determine location Determine distribution Is the radiograph technique used in accordance with code requirements? a. Source type and energy b. Source-to-film distance c. Screens d. Film type e. Geometric unsharpness Written Report: a. Is it complete? All data included? b. Is it clearly legible? c. Is it understandable? Standard terminology used d. Are all technique parameters included? e. Is each film in a series listed? f. Are discontinuities identified? g. Has disposition been made on each film? h. Has the interpreter signed and dated the report and indicated his or her level of certification?
Inspection Trends - April 2011 - Spring
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