Patent ID: 6022173
Filing Date: 2000-02-08
Classification: E02F

Abstract:
An underwater trenching system for forming a trench in a seabed under water, and installing a pipeline into said trench, comprising:a unit frame. said frame having upper and lower ends with a medial area therebetween, first and second sides, and a front and rear end, said medial area of said frame having formed longitudinally therethrough a pipeline passage, said pipeline passage also formed through said front and rear ends, said medial area further comprising upper and lower rollers configured to engage and roll along the pipeline to be installed, said lower rollers supported by roller support members having first and second ends, said first end of each of said roller support members hingedly affixed to one side of said frame, said second end of each of said roller support members releasably affixed to said other side of said frame, so as to provide said roller support members with open, generally vertically aligned positions, and closed, generally horizontally aligned positions, to allow the passage of pipe through the lower end of the frame in said open position, and to allow said lower rollers to generally envelope a portion of the pipe in said closed position;a high pressure jet array situated generally at said front end of said unit frame, comprising a plurality of jet orifices forwardly emanating from the frame so as to provide a stream of high pressure water streams configured to engage and disperse the seabed, so as to form a trench;propulsion means associated with said frame, said propulsion means configured to provide thrust directed rearwardly of said frame, in order to propel said frame in a frontal direction;buoyancy/skid means for alternately providing buoyancy or skids for said unit frame, said buoyancy/skid means further comprising first and second pivot arms each having first and second ends, said first ends pivotally affixed to said frame, said first and second pivot arms extending in opposing directions generally away from said unit frame, said second end of said first pivot arm attached to a first buoyancy chamber, said second end of said pivot arm attached to a second buoyancy chamber, said first and second buoyancy chambers generally axially aligned with the longitudinal axis of said unit frame, said first and second pivot arms being adjustable to position said first and second buoyancy chambers, respectively, to a generally upper position relative said pipeline, away from said seabed, providing buoyancy to the unit frame, said first and second pivot arms being adjustable to position said first and second buoyancy chambers, respectively, to a generally lower position wherein said pontoons are lowered to contact said seabed, providing skids for supporting said unit frame on or over said seabed.