| 摘要 |
<p>A pipe, duct, culvert or building is made from prefabricated sections each of which extends thereabout for less than its circumference, so that there are longitudinal joints between the adjacent sections. Adjacent sections may meet, or may be held spaced apart by connection blocks 7, 8. The sections may have shelves or supports eg. for cables. Preferably sections on either side are offset, so that circumferential joints do not extend continuously thereabout (Figure 10, not shown). <IMAGE></p> |
