SECONDARY LOCK TO SECURE A CONNECTOR CLAMP LEAD SCREW
Publication Date: 2017-Jan-30
The IP.com Prior Art Database
SECONDARY LOCK TO SECURE A CONNECTOR CLAMP
 A connector clamp is often used in subsea applications. For example, a CVC
connector or a CHC connector may be used to join separate sections of production tubing
together. Given the subsea environment, securing and setting the clamp in place in a
permanent fashion is of critical importance. The backing up of the lead screw that is
used to set the clamp at the outset could lead to clamp failure with potentially catastrophic
consequences. Therefore, embodiments of secondary locks and techniques are detailed
herein that uniquely prevent backlash or backing up of the lead screw.
 Alternative efforts have been undertaken to help prevent some of the backlash
in the lead screw. For example, the Vector Double Lock here depicts a double lock type
of device that clamps down on a lead screw (at the top of the picture). However, some
relaxation of the lock on the screw emerges over time.
 The Vector-type of clamp utilizes a secondary lock that allows backing of the
screw due to the lack of a backlash elimination function. This is inherent due to the
incremental nature of the lock utilizing gear-like components.
 A Freudenberg plug as depicted below will allow for losing about 30% of the
preload imparted on the set screw again due to the incremental nature in which the lock
 With this particular device, there are 30 teeth. Given 360°, this means that up
to 12° degrees of loosening is possible with the device in place which translates to the
potential loss of 30% of the pre-load. However, as illustrated here, these efforts are
 However, the embodiments described below, include an infinitely more
accurate set due to the allowance of locking at any position. That is, the locking is not
reliant on incremental predetermined positions but rather may truly lock at any position
as detailed below.
 A subsea secondary lock for a clamp connector is proposed that may be used
to uniquely prevent the backing of the clamp’s lead screw, therefore protecting the clamp
connection from loosening. This ROV operated tool will be placed into an ROV buket
or a torque tool interface. The tool may also be manipulated manually on shore. After
setting the lock in the bucket, the manipulator wrist rotation will be used to clamp the
lock. The secondary lock is provided with a feature to eliminate the backlash in the
installation interface. Notice the lock’s position indicator of OPEN-CLOSED at the top
of the tool which is visible to ROV cameras in the figure here.
 The locked position in particular is provided with its own locking feature to
ensure that the lock remains locked. The rotary lock functions to immobilize the lead
screw in any position as the depicted blue projections rotate outward to grab the inner
wall of the bucket. Thus, reverse rotation is not allowed. Some features of the tool may
- Preventing reverse rot...