| 摘要 |
An adaptor (10) having a concrete cylindrical body (12) with an axial bore (14) having a directional twin seal (24) cast within the body (12) to project into the axial bore (14). The bore (14) has a maximum diameter at each end (16, 18) of the body (12) that decreases to a minimum diameter at the center of the bore (14) where the seal (24) is positioned. The method of constructing the adaptor (10) includes the steps of placing a lower form (44) on a support member (40); placing a seal (54) on the lower form (44); placing an upper form (46) on the seal (54); and placing an outer cylinder (42) around the upper and lower forms (44, 46) to create a space (58) into which liquid concrete is poured.
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