Internal line up clamp

An internal line up clamp and back up ring for damping first and second pipes in proper orientation for welding and providing a back up ring at the weld, comprising:

• a frame;
• a first set of pipe clamps mounted on the frame for movement between a retracted position and a clamping position clamped against the interior surface of the first pipe;
• a mechanism for moving the first set to the clamping position;
• a second set of pipe clamps mounted on the frame for movement between a retracted position and a clamping position clamped against the interior surface of the second pipe;
• a back up ring mounted directly on the frame comprising a plurality of back up ring segments spaced from the second set of pipe clamps and guided by the frame, each back up ring segment for movement between a retracted position and a back up position urged against the interior surface of the first and second pipes;
• each of said back up ring segments including a base moveably mounted to the back up ring, a rod for radial movement relative to the base, a bolt threadedly received in the base to limit the radial motion of the rod and a spring interposed between the base and the rod to urge the rod in the radially outward direction, said back up ring segment further having a u-shaped member mounted thereon, the u-shaped member having a plurality of radially extending elongated slots and a shoe element mounted to the u-shaped member through the slots permitting the shoe element to move radially relative to the u-shaped member and at least one spring interposed between the u-shaped member and the shoe element to urge the shoe element radially outward;
• and
• a mechanism for simultaneously moving the second set of pipe clamps and the back up ring segments into engagement with the pipes.

The method of installing an internal line up clamp and back up ring in a first and second pipe to clamp the pipes in alignment for welding and provide a back up ring at the weld comprising the step of:

• positioning the frame within the interior of the first and second pipes at adjacent ends of the pipes;
• extending a first set of pipe clamps mounted on the frame against the interior surface of the first pipe to clamp the internal line up clamp to the first pipe;
• and
• simultaneously extending a second set of pipe clamps into engagement with the inner surface of the second pipe and extending a plurality of back up ring segments into engagement with the inner surface of the pipes at the weld, the back up ring segments being spaced from the second set of pipe clamps, said back up ring segments each including a base and a rod mounted on the base for motion along a radial axis centered on the center axis of the first and second pipe, a bolt threaded into the base limiting the radially outward movement of the rod, a spring mounted between the base and the rod urging the rod in the radially outward direction, the rod supposing at least one u-shaped plate, a shoe element mounted to the u-shaped plate through elongate slots on the u-shaped plate extending in the radial direction, a second spring mounted between the u-shaped plate and the shoe element to urge the shoe element in the radially outward direction, the first and second springs being resiliently deformed as the back up ring segments are extended into engagement with the inner surface of the pipes to insure that the shoe elements engage the pipes with uniform force.

An internal line up clamp and back up ring for clamping first and second pipes in proper orientation for welding and providing a back up ring at the weld, comprising:

• a frame;
• a first set of pipe clamps mounted on the frame for movement between a retracted position and a clamping position clamped against the interior surface of the first pipe;
• a mechanism for moving the first set to the clamping position;
• a second set of pipe clamps mounted on the frame for movement between a retracted position and a clamping position clamped against the interior surface of the second pipe;
• a back up ring mounted on the frame comprising a plurality of back up ring segments spaced from the second set of pipe clamps, each back up ring segment for movement between a retracted position and a back up position urged against the interior surface of the first and second pipes, the back up ring segments rotating about a radial axis from the center line of the pipes as the back up ring segments move between the retracted position and the back up position;
• each back up ring segment including a base and a rod mounted on the base for motion along the radial axis and about the radial axis relative to the base, a guide member mounted to the frame and having at least one guide pin mounted thereon engaging a groove formed in the rod, the groove extending at an angle relative to the radial axis;
• and
• a mechanism for simultaneously moving the second set of pipe clamps and the back up ring into engagement with the pipes.