Digital Radiographic System for Testing of Boiler Waterwall Tubes for Corrosion Fatigue

作者：Walker Stan M^*

来源：Materials Evaluation, 2010, 68(7): 838-843.

• digital radiography
• fossil power
• plants
• boiler waterwall tubing
• corrosion fatigue
• real-time NDT

Conventional Film radiography has long been a primary weld test technique and has been accepted as a valid means of crack detection for many years; however, it has significant safety requirements, is nonquantitative and results can be slow and difficult to interpret. In addition, conventional film radiography has limitations specifically with corrosion fatigue cracking because of the loss of sensitivity when passing the radiation beam through heavy components on the outside of the boiler.
Technological advances over the last ten years have eliminated the need for film in radiography, removing the need for chemicals used during the development process and allowing for digital storage of images. In 1997, a study by the Electric Power Research Institute (EPRI) showed that the phosphor plate equipment available at the time was effective for a range of utility power plant applications and could be utilized as a testing technique while further refinements were underway.
In the late 1990s, direct-digital radiographic detectors were developed. Initially, the resolution of these detectors was inadequate for detecting cracking and the emphasis of their use was on wall thinning. In 1998, EPRI collaborated with the petrochemical industry to assemble a direct-digital detector radiographic system for the detection of wall thinning in pipe. More recently, improvements in technology have evolved to the point where digital detectors have become smaller and their resolution has improved sufficiently to make them suitable for the identification and analysis of corrosion fatigue cracking (EPRI, 2009).

• 出版日期2010-7