GB915391A - Method and apparatus for radiographic inspection - Google Patents

Abstract

915,391. Radiographic apparatus. ARVANETAKIS, K., and DONZIS, B. A. Dec. 2, 1958 [June 23, 1958; Sept. 15, 1958], No. 38778/58. Class 98 (1). [Also in Group XXIV] A method of making a radiographic film record comprises the steps of moving the ray source relatively to a body which is subjected to a parallel-sided beam of rays from the source, and locating a film at the side of the body remote from the source, the beam passing through the body to the film in a fixed direction during said relative movement. In the form shown, the ray source is an X-ray tube B supported in a travelling carriage A constructed as a framework. Cylindrical lead shields 86, 87 surround the tube to confine the X-rays to a narrow beam. A further removable shield 89 cuts off the lower half of this beam if required. The carriage A has four support arms 37 terminating in wheels 40 which run along the inner surface of pipe P and so support one end of the carriage in position inside the pipe. The other end of the carriage is supported by two arms 23 terminating in wheels 25 mounted in a skewed position with regard to the axis of the pipe. The framework supporting the wheels 25 is rotated by a motor 15, and owing to the skewed position of the wheels a longitudinal force is exerted on the framework, so that the whole carriage assembly is thus moved along the pipe. The photographic film is contained in a holder C (described in more detail in Specification 915,392), mounted on four wheels 72, and running along the outside of the pipe. A selsyn motor 43, mounted on the carriage A and belt-driven from one of the wheels 40, is connected to another selsyn motor 48 mounted on the film holder C where it is connected to a wheel 72. Thus the movement of the filmholder along the outside of the pipe can be synchronized to correspond with the movement of carriage A and X-ray tube B within the pipe. Consequently, a continuous film record of a longitudinal pipe weld may be obtained. In an alternative method for moving the carriage A through the pipe (Fig. 4, not shown), it is mounted on rails, and secured to an endless chain passing over sprockets at each end. In this modification, a variable pulley drive is provided by means of which the speed of movement of the carriage along the pipe can be varied. Also in this modification, the carriage can be moved transversely of the pipe, to bring it closer to one side. Instead of the movable film holder C, a number of stationary cassettes may be distributed along the top of the pipe.