| 摘要 |
A one piece thermoplastic tighthead drum having a drum body, a bottom, a t op and at least one handling ring, at least one of said top and/or bottom including a raised central section surrounded by an annular groove defined by a groove floor, a first sidewall connecting the groove floor and the raised central section and a second sidewall comprising at least a portion of the handling ring. The drum body, the top and/or bottom having the handling ring associated with it and the handling ring converge in an area of merger, the interior surface of which comprises a smooth undulating surface having at least four radii. The configuration provides a double hinge for minimizing the effects of drop impact in the area of merger.</SDOA B>
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