Apparatus and method for laying underwater pipelines

A buoyancy control valve for an underwater pipeline, comprising:

• a) an air escape hole formed on a pipeline;
• b) a sliding weight member disposed over said pipeline upstream and adjacent to said air escape hole, said sliding weight member includes an upper block component, a lower block component, and a sleeve member, said sleeve member disposed over said pipeline capable of freely sliding longitudinally thereover and covering said air escape hole when said pipeline is disposed at a selected inclination, said upper block component and said lower block component being interconnected and attached to said sleeve member;
• c) a first stop means disposed between said pipeline and said sliding weight member which disposes said sliding weight member in a first position on said pipeline immediately adjacent and immediately upstream from said air escape hole;
• d) a second stop means disposed between said pipeline and said sliding weight member to disposed said sliding weight in a second position on said pipeline adjacent and immediately downstream from said air escape hole, said second stop means being located so that said sliding weight member covers said air escape hole when disposed in said second position;
• e) a releasable restraining means disposed between said pipeline and said sliding weight member for selectively controlling the longitudinal movement of said sliding weight member on said pipeline according to the submergence of said pipeline, said releasable restraining means includes a bellows, a frame, and a chain, said bellows and said frame and said chain being connected together so that when said pipeline is submerged a pre-determined depth, said chain is released therefrom which enables said sliding weight member to move from said first position to said second position;
• and,
• f) a sealing means incorporated therein to prevent leakage from said air escape holes.

A method for laying pipeline underwater, comprising the following steps:

• a) selecting a pipeline having a plurality of spaced apart, buoyancy control valves incorporated therein, each said buoyancy control valve includes an air escape hole formed in said pipeline and a sliding weight member, said sliding weight member capable of selectively moving between first and second positions along said pipeline to open and close said air escape hole and thereby, control the buoyancy of said pipeline to enable said pipeline to be submerged and laid in a progressive, controlled manner;
• b) disposing said pipeline on a body of water;
• and,
• c) submerging one end of said pipeline so that water begins to enter and force air therefrom through said air escape holes so that said pipeline begins to progressively sink to the sea floor of said body of water and said buoyancy control valves are activated when said pipeline is submerged a selected depth to close said air escape holes.