An ultrasonic technique for evaluation of heat-exchanger brazed joints

COOK, K. V.AND McCLUNG, R. W. An ultrasonic technique for evaluation of heatexchanger brazed joints. Materials Evaluation, 27 No. 2, p. 97 (1966) This paper describes the development and application of an ultrasonic test for lack of bond in brazed joints used in nuclear heat exchangers. It is a two-transducer frequency-dependent reflection technique suitable for tubes of 0.500-O. 042 in wall thickness. It uses a 5 MC/S miniature probe to fit inside the brazed tubes and can be used both during manufacture and in the actual heat exchanger. A modified commercial ultrasonic display was used. It was possible to detect unbonded areas equivalent to a 3/64 in flat-bottomed hole. (9 figures, 3 references) (Ultrasonics 1966, abstract 509)

CRAWFORD, A. E. Ultrasonic cleaning in mass production. Transactions of the Institute of Metal Finishing, 44, No. 2, p. 5’7 (1966). The latest ultrasonic cleaning techniques are discussed, with special emphasis on large scale production line requirements. Continuous processing by conveyer and adaptibility to automated systems are the important design considerations. Some recently developed’ transducers known as “space laminate transducers” can work at elevated temperatures and can be assembled to any shape and power requirements. It is claimed that the initial cost of ultrasonic installation can be offset within six months by an increase in productivity. (6 figures, 10 references) (Ultrasonics 1966, abstract 510)

DAVIES, D. H. Automatic non-destructive mil.I examination of welded pipe. British Journal of Non-destructive Testing, 8, No. 1, p. 6 (1966). A general discussion on the problems encountered in .. _ fully automated weld examination and on some possible sol&ions. The questions of mechanical handling, scanning and defect marking are considered and it emerges that no single non-destructive testing technique provides a solution to the many problems. In ultrasonic techniques the need for electronic processing of information and for suitable records is stressed. It is suggested that the information derived might be better used for production control than inspection. (2 figures, 4 references) (Ultrasonics 1966, abstract 511)

EDMONDS, P. D. Ultrasonfc absorption cell for normal liqufds. The Review of Scientific Instruments, 37, No. 3, p. 367 (1966) An absorption cell has been developed that can maintain uniform and constant temperature without mechanical agitation during ultrasonic measurements. It consists of the typical thermostatically controlled apparatus with an additional toroidal bypass chamber. The contents of this toroidal reservoir connected to the cell can be circulated to promote uniform mixing and quicker heat exchange. The equipment works at 10 MC/S, sample volume can be 60 or 150 ml, and path length is 100 mm. At 37°C no discernible temperature variation has been observed. (1 figure, 2 references) (Ultrasonics 1966, abstract 512).

EVANS, D. J. Now: Spot hydrogen embrittlement before it becomes a problem. The Oil and Gas Journal, 64, No. 14, p. 160 (1966). Properly controlled ultrasonic tests can provide accurate analysis of the grain structure, internal cracking or fissuring and detect hydrogen embrittlement in refining equipment before it becomes serious. Deterioration in the internal structure of steel, e.g. metal fatigue or decarburization, causes abnormal echo returns which can be detected with the normal flaw detector or attenuation measuring equipment. Low or high temperature ultrasonic probes can be used or permanently installed in on-steam equipment and any subsequent readings compared to the original ones. This paper reports new testing techniques and the development of permanent test stations to overcome the calibration problems in test equipment and probes. (8 tables, 11 references) (Ultrasonics 1966, abstract 513).

FOGLER, H. S., AND TIMMERHAUS, K.D. Effect of ultrasonic waves on mass transfer rates of selected fluids. American Institute of Chemical Engineers Journal, 12, No. 1, p. 90 (1966) Ultrasonic energy greatly increases the rates of mass transfer of fluids in a capillary tube. The maximum evaporation (80@-2000% above normal) at the gasliquid interface occurs at half-wavelength distances along the capillary. Various liquids such as benzene, ethanol, methanol, carbon tetrachloride and acetone yielded the same results. The liquids were contained in 1. 5 mm inside diameter tubes 5 cm long and irradiated at approximately 99 kc/s. Experimental procedures are given and a mathematical model is developed to explain the experimental results obtained. (5 figures, 1 table, 12 references) (Ultrasonics 1966, abstract 514).

GORDON . D . Ultrasonics lo diagnosis. (2 parts). Biomedical Engineering, 1, Nos. 1 and 2, pp. 24 and 58, (1965/ 1966) The application and significance of ultrasonic waves in diagnostics, particularly in echoencephalography, are fully discussed. Other uses such as in opthalmology, obstetrics and cardiology are also mentioned. Ultrasonic equipment is relatively cheap, portable and simple to use but the author stresses the need for medically qualified operators. The equipment gives instantaneous information, can be taken to the scene of accident and at the power levels normally used there are no known dangers. (10 figures, 3 references) (Ultrasonics 1966, abstract 515). BARCOURT, R. W. et al Acoustic amplification in semiconductors. The Radio and Electronic Engineer, 31, p. 145 (1966) The present state of acoustic amplification in semiconductors is reviewed. Both theoretical and experimental aspects of amplifiers using quartz transducers coupled to CdS crystals are discussed. These devices are capable of high gain at v.h.f.frequencies and have immediate applications in ultrasonic delay lines. The evaporation deposited CdS transducers appear to have microwave applications. (11 figures, 1 table, 30 references) (Ultrasonics 1966, abstract 516). ULTRASONICS/July

1966