The internal components of the landing collar are generally fabricated from plastics, cement and other drillable materials.

坐放箍的内部部件一般由塑料、水泥和其它可钻材料制成。

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Several strengthening methods, including stiffened internal ring reinforcement, collar plate reinforcement, internal plate reinforcement and chord thickness reinforcement, are introduced here.

本文介绍了几种加固方法，如内置加劲环加固、环口板加固、内置插板加固和主管壁厚加固等。

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