Abstract: A shell assembly 1 for securing to a tubular member 50 comprises a first part 2 for locating on the tubular member, and second and third parts 4, 6 respectively hinged 8, 10 to opposite sides of the first part. The parts 4 and 6 each have engaging means 40 or 42 complementary to that of the other part. Remotely operable means 20 is used to move the parts 4 and 6 and about hinges 8 and 10 to respective positions whereat the engaging means 40 and 42 interengage so that the parts 4 and 6 are secured together. The shell assembly may be employed in subsea operations to support a damaged region of a pipeline or to enable a branch or tee to be secured to a pipeline.