Coupling for connecting metal tubes end-to-end, particularly in marine pilings

A coupling for connecting metal tubes end-to-end, said coupling comprising

• two tubes forming a tubular bearing pile for use in marine pilings, each tubular pile having one of male and female half-couplings attached to the ends of said two tubes,
• said male half-coupling includes an annular shoulder diverging towards its free end adjacent a portion of said male half-coupling converging towards its free end,
• said female half-coupling includes an edge on the end opposite said attached metal tube, said edge providing a complementary abutment surface for said annular shoulder,
• first and second annular connectors mounted coaxially on the exterior of the male half-coupling and interior of the female half-coupling, respectively,
• said first and second annular connectors being rotatable relatively to each other and fitted to each other in substantially bayonet-like relationship,
• said first annular connector comprises a cylindrical tubular section threaded externally and formed coaxially in said male half-coupling,
• a plurality of grooves formed axially in said cylindrical tubular section and defining a corresponding plurality of axial ribs therein,
• said second annular connector comprises an inside threaded ring nut mounted for rotation coaxially within said female half-coupling,
• a plurality of grooves formed axially in said ring nut and defining a corresponding plurality of axial ribs therein,
• said axial ribs of said ring nut extending substantially over the same length as said axial grooves of said cylindrical tubular element and said axial grooves of said cylindrical tubular section extending over the same length as said axial ribs of said ring nut, and
• displacement means for displacing said ring nut angularly about the axis of said coupling for uniform distribution of axial tightening preload between coupling halves upon displacement of said displacement means to produce a comprehensive stress between said annular shoulder and said edge of said female half-coupling.