In principle, this is a conventional 2 bolt clamp, comprised of two halves:
The lower clamp half is designed to be a permanent fixture on the subsea host structure, e.g. tree, manifold, Flowline End Termination, Pipe Line End Manifold, Riser Base etc. It is totally passive being a machined forging with no moving parts.
The upper clamp half provides the clamp mechanism and contains the two Retlock bolts which open and close the clamp. The nose of the Retlock bolts locates into profiles, reminiscent of a Maltese cross, within the lower clamp half. The Retlock bolt is fitted with safety devices that ensure it is properly located in the lower clamp before any clamping load can be applied.
Should, for any reason, the bolts become inoperable, the system has in-built overrides which ensure that the upper clamp half can be released from the lower clamp half and that all threads and moving parts can be returned to the surface. The DMaC system allows replacement of the upper clamp half without the need to separate the joint, thereby avoiding complex flushing operations and avoiding any risk of hydrocarbons spillage.
In operation the clamp encourages the final alignment of the flowline hubs and provides a substantial pre-load across the face of the hubs. The clamp provides a securing capability greater than the structural integrity of the pipelines, which are being connected
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