| 摘要 |
The tubbing (1) has a convex-curved outer surface (2) and an opposite concave-curved inner surface (3). A thermoplastic layer bulkhead (4) is provided on the convex-curved outer surface and is engaged with a recess provided in the convex-curved outer surface. The outer side surfaces (7) are arranged at the sides of the convex-curved outer surface. A sealing structure is arranged in sealing groove provided in the outer side surfaces. A sealant layer is provided inside the convex-curved outer surface. |
