عنوان مقاله [English]
نویسندگان [English]چکیده [English]
This paper tries to find a suitable probability distribution function for the optical density of the welding lines in the radiographic films. For this purpose, real gamma ray radiography films of the oil and gas pipelines were used in the operational areas of the National Oil Company. The number of the radiographic films was 4 and due to the unpredictability of the radiographic conditions and the existence of different regions on the surface of the films, histogram curves of the scattered data were selected to this investigation. More than 36 probability distribution functions were fitted on the histograms. 11 fitted probability functions with R-sq.≥0.95 were selected among the total functions. In addition, the final selected functions were fitted to 4 internal concavity (Suk Back) defects. Based on our obtained results, the best function was Pearson IV. Although a Gaussian function was also fitted and behaved quite well, but it was found that it is not perfect.
10. M.T. Sasanpour, E.I. Kosarina, Recommendations on selection of anode voltages in X-ray testing of steel specimens, Russ J Nondestruct Test, 47 (5), 48 (2011).
11. Laboratoire National Henri Becquerel (LNHB), www.nucleide.org.
12. ASTM Standard E94, U.S.A., Standard Guide for Radiographic Examination, (2010).
13. ASTM Standard E142-92, U.S.A., Standard Method for Controlling Quality of Radiographic Testing, (2000).
14. ASTM Standard E746, U.S.A., Standard Test Method for Determining Relative Image Quality Response of Industrial Radiographic Film Systems, (2007).
15. ASTM Standard E999, U.S.A., Standard Guide for Controlling the Quality of Industrial Radiographic Film Processing, (2010).
16. ASTM Standard E1032, U.S.A., Standard Test Method for Radiographic Examination of Weldments, (2006).
17. ASTM Standard E1079 U.S.A., Standard Practice for Calibration of Transmission Densitometers, (2017).
18. ASTM Standard E1390, U.S.A., Standard Guide for Illuminators Used for Viewing Industrial Radiographs, (2017).
19. ASTM Standard E1742, U.S.A., Standard Practice for Radiographic Examination, (2011).
20. ASTM Standard E1815, U.S.A., Standard Test Method for Classification of Film Systems for Industrial Radiography, (2008).
21. ASME BPVC Section V: Nondestructive Examination: Article 2 Radiographic Examination, U.S.A., (2015).
22. API International, Welding of Pipelines and Related Facilities: 11.1 Radiographic Test Methods, API Standard 1104, U.S.A., (2013).
23. BS EN ISO 5579: Non-destructive testing. Radiographic testing of metallic materials using film and X- or gamma rays. Basic rules, (2013)
24. BS EN ISO 19232-1: Non-destructive testing. Image quality of radiographs. Determination of the image quality value using wire-type image quality indicators, (2013)
25. BS EN ISO 17636-1:Non-destructive testing of welds. Radiographic testing. X- and gamma-ray techniques with film, (2013)
 BS EN 12681-1: Founding- Radiographic testing. Part 1: Film techniques, (2017).