EXTERNAL DIAMETER MEASURING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an external diameter measuring device which accurately measures an external diameter of a boiler tube in a relatively short period of time.SOLUTION: An external diameter measuring device 100 to measure an external diameter of a cylindrical tube 180 made of alloy steel comprises: a first and a second range finders 111 and 112 which are arranged opposite to each other with the tube 180 placed in between and respectively emit a first and a second laser beams along a longitudinal direction of the tube 180 to measure distances to a circumference of the tube 180; a first and second mirror units 131 and 132 which reflect the first and the second laser beams emitted respectively from the first and the second range finders 111 and 112 to a first point on a first cross section of the tube 180 and a second point opposite to the first point; and a holding unit 140 which holds the first and the second range finders 111 and 112 and the first and the second mirror units 131 and 132 in a manner that enables an external diameter of the tube 180 to be measured on the basis of measurement results of the first and the second range finders 111 and 112 and is detachably installed around the tube 180.SELECTED DRAWING: Figure 3