| 摘要 |
An annular packer (10) for use with an annular blow out preventer (20) formed of a plurality of blades or elements (21,30,72) where each of the blades (21,30,72) is curved and arranged in the annular bore such that the curve of the blade is not parallel with the longitudinal axis of the assembly. This creates an “iris” type of geometry which, as the iris closes, the annular bore (24) transforms from a parallel cylindrical shape to a smaller bore with a shape having at least one waist or pinch point (32,34,73,75) of smaller cross-section. |
| 主权项 |
1. A packer for an annular blow out preventer (BOP) which has a BOP housing defining a through bore, said annular packer being disposed in said housing, said annular packer having a plurality of circumferentially spaced movable elements, each of said elements being substantially identical and moveable radially between a first position where the diameter of the through bore is a maximum and a second position where the diameter is a minimum, piston means disposed in said housing and actuatable for moving said elements from said first position to said second position, each element being curved relative to a plane parallel to a longitudinal axis of the annular BOP and each element being dimensioned and proportioned to fit together with adjacent elements, each element having a curved leading edge, whereby, in use, actuation of said piston means engages each of said elements and moves said elements to the second position, wherein, in the second position, the curved leading edges of said elements define a smaller bore with a narrower cross-section than in the first position. |
