| 摘要 |
<p>A wellhead assembly for a beam pumped production well comprises a stuffing box for providing a seal around a polished rod (1) of the beam pump assembly and a flapper type safety valve (7) for sealing off the wellhead in case of polished rod failure. The safety valve comprises a wear plate (11) which is pressed against the polished rod and means are provided for monitoring the amount of wear of the wear plate on the basis of the angular orientation of the safety valve relative to the stuffing box.</p> |
