Radiation tubing gauge for computing single-wall thicknesses from plural double-wallthickness measurements

Claim 1

APPARATUS FOR MEASURING THE SINGLE-WALL THICKNESS OF A TUBE IN ACCORDANCE WITH THE RADIATION ABSORPTION OF DOUBLE-WALL THICKNESSES THEREOF AT AT LEAST THREE POINTS SPACED ON THE CIRCUMFERENCE OF SAID TUBE COMPRISING MEANS INCLUDING A RADIOACTIVE SOURCE FOR PASSING A BEAM OF PENETRATIVE RADIATION THROUGH THE WALL OF SAID TUBE ALONG A LINE DETERMINED BY A PAIR OF SAID POINTS, MEANS FOR QUANTITATIVELY DETECTING THE RADIATION PENETRATING SAID WALL AT SAID PAIR OF POINTS BY GENERATING A SIGNAL SYSTEMATICALLY RELATED TO SAID DETECTED RADIATION, MEANS FOR REPEATING SAID OPERATION FOR DIFFERENT PAIRS OF SAID POINTS SO THAT RADIATION PENETRATING SAID WALL AT EACH POINT IS DETECTED TWICE, EACH TIME AFTER PENETRATING THE WALL AT A DIFFERENT ONE OF THE OTHER OF SAID POINTS, AND MEANS FOR COMBINING SAID SIGNALS TO PRODUCE SIGNALS INDICATIVE OF THE SINGLE-WALL THICKNESS AT EACH OF SAID POINTS.