| 摘要 |
<p>A pipe is assembled from lengths of pref. coated mesh, with one or more weld seams on the longitudinal edges, as flexible air duct for use in underground mine operations. The lengths (40,41) are provided, on one or both sides, with strips (44-47,50-53) of reflecting or fluorescent paint, aligned at right angles to their edges, at regular spacings. The edges (48,49,54,55) of the printed strips are aligned on the weld seams. Strips on one side of a length are pref. flush with those on the opposite side. Any faults in edge alignment are clearly visible before welding is carried out.</p> |
