External tieback connector and method for tying back riser to subsea wellhead

A connector for connecting a riser from a platform to a subsea wellhead member, the wellhead member having external grooves thereon, comprising:

• a connector body adapted to be joined to the riser for landing on an upper end of the well, the connector body having a longitudinal axis;
• a connector housing depending concentrically from the connector body for insertion over the wellhead member;
• a locking member moveably carried by the connector housing and adapted to mate with and lock in the external grooves;
• a cam ring carried moveably within the connector housing to force the locking member inward into engagement with the external grooves;
• and
• a transfer member extending upward and inward from an interior portion of the connector housing, the transfer member having an upper end portion in engagement with a lower end of the locking member, the upper end portion being located at a lesser radial distance from the axis than the interior portion of the connector housing so as to define a load path that is inclined relative to the axis.

A connector for connecting a riser from a platform to a subsea wellhead housing, the wellhead housing having external grooves thereon, comprising:

• a connector body adapted to be joined to the riser;
• an outer housing depending from the connector body, the outer housing having an internal generally upward facing shoulder;
• an inner housing concentrically joined to the outer housing and forming an annular cavity between the inner housing and the outer housing;
• a locking member moveably carried in the annular cavity and adapted to mate with and lock in the external grooves;
• a cam ring carried within the cavity for axial movement relative to the locking member for forcing the locking member into engagement with the external grooves;
• and
• a plurality of transfer links, each of the links having an upper end portion in engagement with the locking member and a lower end portion in engagement with the shoulder in the outer housing to transfer axial loads between the outer housing and the locking member, the upper end portion defining an inner diameter and an outer diameter, the lower end portion defining an inner diameter and an outer diameter, the inner diameter of the lower end portion being greater than the outer diameter of the upper end portion.

A method of joining a subsea first cylindrical member with a subsea second cylindrical member, comprising:

• providing the first cylindrical member with a plurality of grooves;
• positioning the second cylindrical member concentrically relative to the first cylindrical member, the second cylindrical member carrying an radially movable locking member and having a transfer member, the transfer member having, an upper end portion engaging the locking member, the upper end portion having an outer edge, the transfer member having a base portion that is supported by the second cylindrical member, the base portion having an outer edge that is closer to the second cylindrical member than the outer edge of the upper end portion;
• actuating the locking member into engagement with the grooves;
• and
• transferring axial loads imposed on the locking member through the transfer member to the second cylindrical member at an acute angle relative to a plane perpendicular to a longitudinal axis of the first cylindrical member.