The invention pertains particularly to wellhead connectors of the type which are connected to subsea wellheads to provide a means for mounting blowout preventor stacks or other apparatus on such wellheads. However, in its broader aspects, the invention may be more generally applied to systems for connecting two tubular bodies in generally coaxial alignment. Such wellhead connectors typically include latches carried on some type of generally tubular main body. The latches may be extended radially inwardly, either by a pivotal type movement or a rectilinear type movement, to engage cooperative profiles on the wellhead to latch the main body to the wellhead. The latches and cooperative wellhead profiles are typically configured, i.e. with mating inclined surfaces, so that, at least in theory, as the latches are urged radially inwardly into tighter engagement with the wellhead, the connection is also tightened longitudinally, a firm connection being important for any number of reasons well known in the art. Accordingly, various systems have been devised for so urging the latches radially inwardly with a high mechanical advantage. However, it has been found that, in practice, the application of high radial forces to the latches with such systems simply does not result in the tight connection between the connector body and wellhead which should theoretically result.
It is believed that at least one reason for this undesirable phenomenon is that the industry standards concerning wellhead materials require metalurgical properties which, while making the wellhead resistant to corrosion, etc., also necessitate the use of a relatively soft metal in the wellhead. Then, the high radial forces being applied to the latches, rather than effectively utilizing the inclined surfaces on the latches and wellhead to tighten the connection longitudinally, may simply cause the latches to dig into and deform the wellhead material without effecting any further longitudinal movement.