Abstract: A method of launching an elongate subsea structure such as a pipeline bundle unit into water provides buoyant support to the structure by displacing water with a hollow buoyancy unit that applies buoyant upthrust to the structure. By lowering the buoyancy unit in the water to bring a permanently open aperture of the buoyancy unit beneath a surface level of the water, the buoyancy unit is flooded with water through the or each permanently open aperture to reduce the buoyant upthrust applied to the structure. A corresponding elongate subsea structure is also claimed.

Abstract: A bundle section of a subsea pipeline bundle has a rigid carrier pipe having an end closed by a transverse bulkhead and one or more fluid conduits in fluid communication with an opening that penetrates the bulkhead. Fluid coupling formations such as a spigot or a recess on an outer face of the bulkhead surround the opening. Leak-tight coupling between successive fluid conduits is effected when the bulkheads of two such bundle sections are brought together. This forces together opposed complementary fluid coupling formations of the bulkheads. The bulkheads connect the adjoining bundle sections fluidly and mechanically.

Abstract: A method of launching an elongate subsea structure such as a pipeline bundle unit into water provides buoyant support to the structure by displacing water with a hollow buoyancy unit that applies buoyant upthrust to the structure. By lowering the buoyancy unit in the water to bring a permanently open aperture of the buoyancy unit beneath a surface level of the water, the buoyancy unit is flooded with water through the or each permanently open aperture to reduce the buoyant upthrust applied to the structure.

Abstract: A bundle section (20) of a subsea pipeline bundle comprises a rigid carrier pipe (12) having an end closed by a transverse bulkhead (26A, 26B), and one or more fluid conduits in fluid communication with an opening that penetrates the bulkhead. Fluid coupling formations such as a spigot or a recess on an outer face of the bulkhead surround the opening. Leak-tight coupling between successive fluid conduits is effected when the bulkheads of two such bundle sections are brought together. This forces together opposed complementary fluid coupling formations of the bulkheads. The bulkheads connect the adjoining bundles sections fluidly and mechanically.