| 摘要 |
<p>A V-shaped frame 102 is attached to a pipe 100 to be drilled. The frame may be used with larger pipes by attaching a removable extension plates 120 to the arms 104 106 of the V-shaped frame, thereby increasing the size of the recess between the arms 104, 106. The apparatus may be fixed to the pipe 100 by a chain 110 which connects to the platform 102 and extends around the pipe 100, or by attaching clips to the frame and attaching the clips to the surface of the pipe by screws etc.</p> |
