| 摘要 |
The wellhead seal comprises a seal body 12 having internal circumferential ridges 22, 24, 26 for sealing engagement with the well casing and rounded external circumferential shoulders 16a, 18a, 20a between stepped outer cylindrical surfaces of the seal body, for engagement with a component of the wellhead. The shoulders 16a, 18a, 20a lie tangentially to a straight line L which converges with the well casing at a small angle, e.g. 4 DEG . This angle corresponds to the taper angle of the wellhead component in which the seal body 12 is installed, so that radial inward deformation of the seal body 12 occurs evenly during installation whereby its internal sealing ridges 22, 24, 26 establish a uniform metal-to-metal seal with the opposed casing surface, without the need to specially machine that surface. The seal body may be energised by a body (40, fig. 2; 140, fig. 4) acted on by lockdown screws (54, fig. 2) or hydraulic pressure (fig. 4). <IMAGE>
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