| 摘要 |
<p>The metal tank has an inner chamber (2) accessed via an inspection port (4) with a manhole (5) formed by a ring (6) with a surrounding collar (8) at an angle of 45 - 90 degrees to the axis (A) of the manhole. In a variant the collar can be made with curved surfaces enabling its outer edge to be higher than its inner edge adjoining the ring, where it has a seal (11).</p> |
