Advanced Inspection Methods 3 1 (103.49 KiB) Viewed 16 times
Advanced Inspection Methods 3 2 (14.42 KiB) Viewed 16 times
Exercise 3 (20 marks) (LO: a, b, d, e & f) a) Calculate the depth of penetration 8 at a frequency of 100 kHz for austenitic stainless steel 316 and mild carbon steel, where is the electrical conductivity and μ is the magnetic permeability. Comment on what kind of eddy current inspections can be carried out in each case. Relative magnetic permeability μ... Stainless steel 316 Mild carbon steel Electrical conductivity o Siemens/m 2.0 x 106 5.9 x 106 1.005 100 (6 marks) b) In order to discriminate between a defect breaking the surface of a stainless steel sample and a defect embedded at a depth of 1.5 mm, a phase difference of 45° is required. Explain how this can be achieved. (Give an appropriate numerical answer). (4 marks)
c) Draw a B-H graph for a ferromagnetic material and use it to explain a technique which enables a ferromagnetic material to be inspected to a deeper penetration depth than would be expected. (5 marks) A carbon steel tube forming part of a heat exchanger is to be inspected using remote field testing at a frequency of 500 Hz. It is suspected that there are defects 0.5 mm in diameter distributed along the tube. Give a recommendation for the pull speed of the probe, stating the assumptions you make in your calculation. (5 marks)
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