Connection tool with indexing system

1. A connection tool for connecting a pipeline to a subsea connection structure which includes a connection porch into which the pipeline is connected, at least one locating post being positioned adjacent to the connection porch, the tool comprising:

a tool chassis;

a carrier mounted on the chassis and adapted to releasably carry the pipeline to be connected to the connection structure; and

at least one locating member positioned at the front of the chassis so as to be engageable with the or each locating post on the connection porch to hold the chassis adjacent to the connection porch, a hinge connecting the locating member to the chassis that allows pivoting movement around a transverse axis such that the azimuthal orientation of the chassis relative to the connection porch can be varied when the or each locating member is engaged with its respective locating post,

wherein the or each locating member includes a locking member that engages its respective locating post when the locating member is engaged thereon and prevents disengagement of the locating member unless the chassis is in a predetermined azimuthal orientation relative to the connection porch.

2. A connection tool as claimed in claim 1 , wherein the locating member comprises a sleeve that can slide over the locating post to hold the chassis in position relative to the connection porch.

3. A connection tool as claimed in claim 2 , wherein a pair of hinged sleeves are provided on the chassis in an arrangement corresponding to that of a pair of locating posts on the connection porch.

4. A connection tool as claimed in claim 1 , wherein the hinge includes a cam surface that acts on the locking member.

5. A connection tool as claimed in claim 4 , wherein hinging of the chassis away from the predetermined azimuthal orientation causes the cam surface to act on the locking member to urge it into engagement with the locating post.

6. A connection tool as claimed in any preceding claim, wherein the locking member comprises a peg that engages in a slot in the locating post.

7. A method of connecting one end of a pipeline into a connection porch on a subsea connection structure, at least one locating post being positioned adjacent to the connection porch, the method comprising:

attaching the end of the pipeline to a connection tool comprising:

a tool chassis;

a carrier mounted on the chassis for carrying the end of the pipeline to be connected to the connection structure;

at least one locating member positioned at the front of the chassis, the locating member including a locking member; and

a hinge connecting the locating member to the chassis;

maneuvering the connection tool such that the locating member engages with the locating post when the chassis is in a predetermined azimuthal orientation relative to the connection porch;

varying the azimuthal orientation of the chassis relative to the connection porch, thereby causing the locking member to engage the locating post and prevent disengagement of the locating member;

connecting the end of the pipeline to the connection structure at the connection porch;

detaching the pipeline from the connection tool;

returning the chassis to the predetermined azimuthal orientation such that the locking member is disengaged from the locating post;

disengaging the locating member from the locating post; and

maneuvering the connection tool away from the connection structure.

8. A method as claimed in claim 7 , wherein the connection porch faces in a downward direction and the locating post projects upward from the connection porch, the method comprising engaging the locating post with the locating member with the chassis in the predetermined orientation, hinging the chassis downwards to bring the end of the pipeline into alignment with the downward facing connection porch, connecting the pipeline to the connection porch and raising the chassis back to the predetermined orientation for disengagement from the locating post.

9. A method as claimed in claim 7 , when performed using a connection tool as claimed in any of claims 1 - 5 .