Valve radiographic testing technology

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As a component of special equipment, valve plays an increasingly important role with the vigorous development of electric power, petroleum, chemical industry, metallurgy, shipbuilding, nuclear energy and aviation. Developed countries in the world have paid considerable attention to the safety and quality of its manufacturing. For various reasons, China began to license the manufacturing qualification of pressure valves and supervise and inspect the manufacturing quality in February 2003. In the past, due to the poor control of valve quality, valve leakage or valve body fracture accidents often occurred, resulting in heavy losses of people's lives and property. Through the research on the application of radiographic testing technology in the field of valve body inspection, this paper has played a good role in promoting the effective control of valve manufacturing quality and improving the economic benefits of enterprises. Now, the state has promulgated relevant regulations on the manufacturing quality control of valves and formulated corresponding standards. The application of nondestructive testing in valve inspection is also mentioned in the standards. However, due to the variety of valve size and thickness, the application of radiographic testing in the field of valve inspection has a short history. Therefore, the process of radiographic testing of valve defects is still not mature, and there is great randomness, which is easy to cause defect omission and economic waste. This paper discusses in detail the properties of rays, various effects and attenuation laws when rays penetrate substances, and the principle of radiography, and deeply analyzes various factors affecting the contrast, unsharpness and granularity of negative films. Starting from the three major factors affecting the sensitivity of flaw detection, the selection of ray source, focal length, transmission mode, film, backscatter and other processes is studied, and the principles for selecting various transmission modes are specified; According to the general formula of small defects, combined with the transillumination thickness ratio specified in the national standard, the minimum number of films taken by various transillumination methods is deduced. In this paper, the characteristics of radiographic equipment and equipment are studied, and different radiographic inspection systems are designed. The defective valves are radiographic inspected according to the traditional radiographic method and the radiographic technology studied in this paper. The obtained defective negatives are compared to verify that the defective negatives with better contrast, unsharpness and granularity can be obtained according to the radiographic technology in this paper, and the radiographic results are analyzed and summarized, It provides valve manufacturers with radiographic testing technology that can not only ensure the inspection quality, but also improve the economic benefits.

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