| 摘要 |
<p>PURPOSE:To enable the X-ray examination of the welded parts of a main pipe that has been welded inside a starting shaft to be easily carried out from the outside by providing a space between the adjacent outer pipes in the piping material of a small-diameter double structure. CONSTITUTION:A filling material layer 21 is formed on the outside of main pipes 20 whose both ends have been beveled, and a water-feeding pipe 22 and a mud-water pipe 23 are penetrated through the filling material layer 21. On the outside of the filling material layer 21, outer pipes 24 whose length between both ends is shorter than the main pipe 20 and that is formed so as to be concentric with the main pipe 20 are provided for constituting a piping material of a small-diameter double structure. After the main pipes 20 have been welded to each other in the inside of a starting shaft and subjected to the X-ray examination from the space formed between adjacent outer pipes 24, the water-feeding pipes 22 and mud-water pipes 23 are connected by means of connecting pipes 16 respectively. A sliding working layer may be interposed between the filling material layer 21 and the outer pipe 24.</p> |
