Engineering topics
Publications and source records attributed to Kleint, R. E..
Eddy-current measurements detect wear of thin walls (0.01 in) (0.25 mm) in small diameter (0.19 in) (5 mm) heat exchanger tubing. Flexible durable thin rod inserts eddy-current coil into the heatexchanger tube.
Inspection technique for narrow-bore metal tubing involves use of small internal eddy-current probe. Probe consists of thin copper wire wrapped on bobbin. Probe small enough to pass through bends in tube being measured. Technique useful for strain measurements where operating conditions or inaccessibility prevent use of such conventional methods as X-ray diffraction, electrical-resistance measurements, strain gages, or holography.
Foil or thin wire at weld root is used to verify weld penetration. When weld is adequate, material mixes with weld and traces of it diffuse to weld crown. Spectroscopic analysis of samples identifies foreign material and verifies root has fused. Weld roots are usually inaccessible to visual inspection, and X-ray and ultrasonic inspection techniques are not always reliable. Good results are obtained with use of gold/nickel alloy.
Ultrasonic equipment and x-y recorder indicate where back side of joint is properly welded. Wire waveguide placed in groove at root of joint to be welded is fused when joint is adequately penetrated. Ultransonic signal moving down waveguide is reflected where guide is melted. Change in reflected-signal arrival time with change in weld-head position is nearly constant unless joint is incompletely penetrated. Method permits determination of penetration depth in preweld samples without opening vacuum chamber and sectioning weld. Technique is particularly valuable when back side of joint is inaccessible.
Small holes drilled along back edge of surface to be joined are filled when weld root is adequately fused. Holes 2% of thickness of material can be detected with X-rays. Absence of detectable holes indicates good weld. Procedure has been proven in production and is more reliable than conventional X-ray methods.