Full opening bulged forward acting rupture disc having variable depth score line

Abstract

A leak integrity testing apparatus ( 36 ) is provided which is adapted to be inserted within a liquid-delivery line, as for example an oil well tubing string ( 26 ), to permit in situ testing of the line or string ( 26 ) without the need for removal or inspection of the line. The apparatus ( 36 ) is a tubular body preferably including an interconnected tubular inlet ( 38 ) and outlet ( 40 ); a liquid pressure-responsive, metallic burst disc ( 42 ) is located between the inlet ( 38 ) and outlet ( 40 ). The disc ( 42 ) includes a peripheral flange ( 62 ) and an inner concavo-convex burst region ( 64 ). A score line ( 82, 86 ) is located on the concave face ( 66 ) of the burst region ( 64 ), and is of differential depth, having a reduced-depth hinge area ( 84, 88 ) serving to prevent detachment of the burst region ( 64 ) upon actuation of the disc ( 42 ). The score line ( 82 ) preferably is located entirely inboard of the transition region ( 76 ) between the flange ( 62 ) and burst region ( 64 ); alternately, the score line ( 86 ) may have the hinge area ( 88 ) thereof within the transition region ( 76 ). In use, liquid under pressure less than the burst pressure of the disc directed against the concave face ( 66 ) of the disc ( 42 ) thereby confirming the integrity of the line or string ( 26 ). Increasing the pressure of the liquid against the concave face of the disc to a level which effects rupture of the disc, the central ruptured section of the disc gives way and moves to an open position allowing substantially unimpeded flow of liquid through the opening in the disc defined by the ruptured section.

We claim:  
     
         1 . A unitary, forward buckling, rupture disc adapted to be mounted on a tubular rupture disc holder in closing relationship to a central fluid passage through the holder, said disc comprising: 
 an outer peripheral flange portion having a first annular face and an opposed second annular face,    an inner concavo-convex, generally hemispherical bulged region presenting a concave face and an opposed convex face,    an annular, circumferentially extending, cross-sectionally arcuate transition region integral with the peripheral flange portion and the bulged region respectively, said transition region having a first cross-sectionally arcuate annular surface joining the first face of the flange portion to the convex face of the bulged region and a second cross-sectionally arcuate annular surface joining the second face of the flange portion to the concave face of the bulged region, said first arcuate surface being defined by a pair of circumferentially extending, concentric, laterally spaced apart, inner and outer first margins integral with the first annular face of the flange portion and with the convex face of the bulged region respectively, said second arcuate surface being defined by a pair of circumferentially extending, laterally spaced apart, inner and outer second margins integral with the second annular face of the flange portion and with the concave face of the bulged region respectively, said first arcuate surface having a smaller radius than the radius of the second arcuate surface, and    said bulged region being provided with a continuous, generally circular score line formed in the concave face of the bulged region inboard of and spaced inwardly of the transition region, said score line defining a central rupture segment of the bulged region having a generally circumscribing edge located in proximal relationship to the inner second margin of the transition region,    said score line varying in depth along the length thereof presenting a first reduced depth line portion defining a hinge section of the score line and defining a second score line portion of greater depth than said reduced depth score line portion, said second score line portion being of a depth to rupture and allow the central rupture segment of the bulged region to move to a fully open position when a pre-determined pressure is applied to the concave face of the rupture disc, said second score line portion of the score line being located in sufficiently close relationship to the inner second margin of the transition region and of a depth such that the central rupture section of the bulged disc region opens to said fully open position without severing of the hinge section of the disc and with the edge of the central rupture disc segment disposed in at least about substantially perpendicular relationship to said flange,    said central rupture segment of the disc when moved to the fully open position thereof being located out of the flow path of fluid through the rupture disc holder so as to not present any substantial impediment to bi-directional flow of fluid through said central passage of the rupture disc holder    
     
     
         2 . A unitary, forward buckling rupture disc as set forth in  claim 1 , wherein said disc has a thickness of from about 0.010 in. to about 0.060 in.  
     
     
         3 . A unitary, forward buckling rupture disc as set forth in  claim 2 , wherein said disc has a thickness of from about 0.014 in. to about 0.050 in.  
     
     
         4 . A unitary, forward buckling rupture disc as set forth in  claim 1 , wherein said second line portion of the score line is from about 35% to about 70% of the thickness of the disc.  
     
     
         5 . A unitary, forward buckling rupture disc as set forth in  claim 4 , wherein said second line portion of the score line is from about 40% to about 60% of the thickness of the disc.  
     
     
         6 . A unitary, forward buckling rupture disc as set forth in  claim 1 , wherein the depth of said first score line portion of the score line is from about 0.001 in. to about 0.005 in. less than the depth of the second score line portion of the score line throughout the extent of the first score line portion.  
     
     
         7 . A unitary, forward buckling rupture disc as set forth in  claim 1 , wherein the depth of said second score line portion of the score line is from about 0.002 in. to about 0.004 in. less than the depth of said first score line portion of the score line.  
     
     
         8 . Apparatus for testing the integrity of the connections between end to end pipe sections of a liquid-delivery pipe string line within an oil well casing and thereafter permitting full bi-directional flow of liquid through the pipe string, said apparatus comprising: 
 a tubular rupture disc holder presenting a central liquid passage therethrough and having opposed end segments, one of said holder end segments being adapted for attachment to an end of one of the pipe sections of the pipe string and the other end segment of the holder being adapted to for attachment to an end of an adjacent pipe section of the pipe string, said holder being provided with a circumferentially extending enlarged central section of greater diameter than the diameter of each of the opposed end segments of the holder; and    a unitary, forward buckling, rupture disc mounted on the rupture disc holder in normal closing relationship to said central liquid passage through the holder, said disc provided with 
 an outer peripheral flange portion having a first annular face and an opposed second annular face,  
 an inner concavo-convex, generally hemispherical bulged region presenting a concave face and an opposed convex face,  
 an annular, circumferentially extending, cross-sectionally arcuate transition region integral with the peripheral flange portion and the bulged region respectively, said transition region having a first cross-sectionally arcuate annular surface joining the first face of the flange portion to the convex face of the bulged region and a second cross-sectionally arcuate annular surface joining the second face of the flange portion to the concave face of the bulged region, said first arcuate surface being defined by a pair of circumferentially extending, concentric, laterally spaced apart, inner and outer first margins integral with the first annular face of the flange portion and with the convex face of the bulged region respectively, said second arcuate surface being defined by a pair of circumferentially extending, laterally spaced apart, inner and outer second margins integral with the second annular face of the flange portion and with the concave face of the bulged region respectively, said first arcuate surface having a smaller radius than the radius of the second arcuate surface, and  
 said bulged region being provided with a continuous, generally circular score line formed in the concave face of the bulged region inboard of and spaced inwardly of the transition region, said score line defining a central rupture segment of the bulged region having a generally circumscribing edge located in proximal relationship to the inner second margin of the transition region,  
 said scored line varying in depth along the length thereof presenting a first reduced depth line portion defining a hinge section of the score line and defining a second score line portion of greater depth than said reduced depth score line portion, said second score line portion being of a depth to rupture and allow the central rupture segment of the bulged region to move to a fully open position when a pre-determined pressure is applied to the concave face of the rupture disc, said second score line portion of the score line being located in sufficiently close relationship to the inner second margin of the transition region and of a depth such that the central rupture section of the bulged disc region opens to said fully open position without severing of the hinge section of the disc and with the edge of the central rupture disc segment disposed in at least about substantially perpendicular relationship to said flange,  
 said central rupture segment of the disc when moved to the fully open position thereof being located in the enlarged central section out of the flow path of liquid through the rupture disc holder so as to not present any substantial impediment to bi-directional flow of liquid through said central passage of the rupture disc holder.  
   
     
     
         9 . Apparatus for testing the integrity of the connections between end to end pipe sections of a liquid-delivery pipe string line within an oil well casing as set forth in  claim 8 , wherein said disc has a thickness of from about 0.010 in. to about 0.060 in.  
     
     
         10 . Apparatus for testing the integrity of the connections between end to end pipe sections of a liquid-delivery pipe string line within an oil well casing as set forth in  claim 9 , wherein said disc has a thickness of from about 0.014 in. to about 0.050 in.  
     
     
         11 . Apparatus for testing the integrity of the connections between end to end pipe sections of a liquid-delivery pipe string line within an oil well casing as set forth in  claim 8 , wherein said second line portion of the score line is from about 35% to about 70% of the thickness of the disc.  
     
     
         12 . Apparatus for testing the integrity of the connections between end to end pipe sections of a liquid-delivery pipe string line within an oil well casing as set forth in  claim 11 , wherein said second line portion of the score line is from about 40% to about 60% of the thickness of the disc.  
     
     
         13 . Apparatus for testing the integrity of the connections between end to end pipe sections of a liquid-delivery pipe string line within an oil well casing as set forth in  claim 8 , wherein the depth of said first score line portion of the score line is from about 0.001 in. to about 0.005 in. less than the depth of the second score line portion of the score line throughout the extent of the first score line portion.  
     
     
         14 . Apparatus for testing the integrity of the connections between end to end pipe sections of a liquid-delivery pipe string line within an oil well casing as set forth in  claim 8 , wherein the depth of said second score line portion of the score line is from about 0.002 in. to about 0.004 in. less than the depth of said first score line portion of the score line.