Quantitative characterization of corrosion under insulation
Tóm tắt
A method is described to quantitatively characterize the corrosion status of steel samples under insulation. The method uses backscatter X-rays to obtain a density vs. depth profile of the sample, from which the mass absorption coefficient, density, and thickness of the rust layer are evaluated. From these data, the iron content of the rust layer is computed, and the steel losses are expressed in either wall thickness or in the mass per unit area. Rust with a thickness of less than 1 mm can be detected but not quantified. The upper limit for quantitative expression of steel losses is approximately 6 mm when an X-ray tube operated at 160 KV is used.
Tài liệu tham khảo
W. S. Burkle, Application of the tangential radiographic technique for evaluating pipe system erosion/corrosion, Mater. Eval. 47: 1184 (1989).
P. W. Lott and J. Lott, Near real-time radiologic corrosion monitoring of Arctic petroleum gathering lines, Mater. Eval. 43: 408–412 (1985).
S. Bukshpan and D. Kedem, Detection of imperfections by means of narrow beam gamma scattering. Mater. Eval. 33:243–245 (1975).
G. Harding. On the sensitivity and application possibilities of a novel Compton scatter imaging system, IEEE Trans. Nucl. Sci. NS-29(3) (June 1982).
H. Strecker, Scatter imaging of aluminum castings using an X-ray fan beam and a pinhole camera, Mater. Eval. 40:1050–1056 (1982).
J. A. Stokes, K. R. Alvar, R. L. Corey, D. G. Costello, J. John, S. Kocimsky, N. A. Lurie, D. D. Thayer, A. P. Trippe, and J. C. Young, Some new applications of collimated photon scattering for nondestructive examination. Nucl. Instr. Meth. 193: 261 (1982).
G. Harding, H. Strecker, and R. Tischler, X-ray imaging with Compton-scatter radiation, Philips Technol. Rev. 41(46) (1983/84).
G. Harding and R. Tischler, Dual energy Compton scatter tomography, Phys. Med. Biol. 41:477–489 (1986).
B. Bridge, A theoretical feasibility study of the use of Compton backscatter gamma-ray tomography (CBGT) for underwater offshore NDT, Brit. J. Nondestr. Testing (Nov. 1985).
A. Viswanth, A Study of a Thickness Probe for Steel Using Backscatterd X-Rays, MS theis, UH (1991).
P. S. Ong, Material Losses in Steel Pipes Under Insulation, Technical Report for EXXON, University of Houston (1991).
J. H. Hubbell, Photon Cross Sections, Attenuation Coefficients and Energy Absorption Coefficients from 10 KeV to 100 GeV, NSRDS-NBS 29 (1969).
Qiu Feng, W. L. Anderson, and P. S. Ong, Deconvolution of X-ray backscatter diffraction data for NDE, in Review of Progress in Quantitative NDE (University of California at San Diego, La Jolla, July 19<24, 1992).
A. Balasubramanyan, Quantitative Evaluation of Corrosion by Analysis of Backscattered X-Ray Data, MS thesis, UH (1994).
V. Patel, Nondestructive Evaluation of Material Loss due to Corrosion Using Backscatter X-Ray Technique, MS thesis, UH (1993).