Tensioning arrangement for a subsea wellhead assembly

A pre-tensioning arrangement for inner and outer elongate concentric members includes a load member which is axially movable in an actuating direction relative to the inner member and has an outer surface which tapers in the actuating direction, a laterally expansible ring which is engaged by the load member in an inclined engagement zone during the actuating movement, and an engagement zone between the laterally expansible ring and the outer member, the engagement zones providing a mechanical advantage between the movement of the load member and movement of the outer member.