Seal

Abstract

A seal is inserted into a space to be sealed. First and second end portions of the seal are engaged with first and second end surfaces of the space. The seal is compressed between the first and second end surfaces. The compression strains the seal. The strain includes the rotation of a cross-section of the seal so as to bias the seal into engagement with a surface forming one of an inboard surface and an outboard surface of the space.

1 . A method for sealing a space formed by first and second end surfaces adjacent inboard and outboard surfaces, the method comprising:
 inserting a seal into the space without radial interference with inboard or outboard surfaces;   engaging first and second end portions of the seal with the first and second end surfaces of the space;   locally compressing the seal between the first and second end surfaces; and   straining the seal to rotate a cross-section of the seal to bias the seal into engagement with the inboard and outboard surfaces of the space, the straining including a terminal portion of the compressing acting to shift the seal into said engagement with said inboard and outboard surfaces of the space.   
     
     
         2 . The method of  claim 1  wherein the straining comprises:
 exposing the seal to an operational fluid pressure difference across the seal in the space, the pressure difference acting to shift the seal into said engagement with the other one of said inboard and outboard surfaces of the space. 
 
     
     
         3 . The method of  claim 1  wherein:
 the first and second end surfaces are base surfaces of first and second channels in first and second flanges. 
 
     
     
         4 . The method of  claim 3  wherein:
 the first and second end surfaces are surfaces of first and second flanges, respectively, and the compressing bottoms said first and second flanges without bottoming the seal relative to the first and second flanges. 
 
     
     
         5 . The method of  claim 1  wherein:
 the first and second end surfaces are surfaces of first and second flanges; and with the first and second flanges bottomed against each other, the seal is not bottomed. 
 
     
     
         6 . The method of  claim 1  wherein:
 the first and second end surfaces are surfaces of first and second flanges; and 
 with the first and second flanges bottomed against each other, engagement regions of the first and second end portions of the seal with the first and second end surfaces remain radially spaced apart and radially non-overlapping. 
 
     
     
         7 . A method for sealing an annular-shaped space, the method comprising:
 inserting a seal into the space without radial interference inboard or outboard;   engaging first and second end portions of the seal with first and second end surfaces of the space;   compressing the seal between the first and second end surfaces, the compressing bottoming first and second members respectively having the first and second end surfaces without bottoming the seal relative to the first and second members; and   straining the seal to rotate a cross-section of the seal to bias the seal into engagement with the inboard and outboard surfaces of the space;   and shifting the seal into engagement with said inboard and outboard surfaces of the space.   
     
     
         8 . The method of  claim 7  wherein:
 the engaged first and second end portions are offset normal to a direction of the compressing so as to provide a force couple to induce the rotating. 
 
     
     
         9 . The method of  claim 7  wherein:
 the seal is a continuous annulus and the first and second end portions are radially offset from each other normal to a central axis of the seal. 
 
     
     
         10 . The method of  claim 7  further comprising:
 exposing the seal to an operational fluid pressure difference across the seal in the space, the pressure difference acting to increase an engagement bias of the seal against at least one of the inboard and outboard surfaces. 
 
     
     
         11 . The method of  claim 7  wherein:
 said cross-section has an exterior perimeter formed as a rounded-corner trapezoid, and wherein, in a relaxed condition, the base and top of the trapezoid have off-longitudinal normals. 
 
     
     
         12 . The method of  claim 11  wherein:
 the engaging is along first and second diagonally opposite said rounded corners; and 
 a combination of the compressing and an operational pressure difference brings the third and fourth said rounded corners into respective engagement with the inboard and outboard surfaces. 
 
     
     
         13 . The method of  claim 7  wherein:
 said cross-section has an exterior perimeter having first and second rounded ends and first and second sides; 
 the engaging brings a first portion of the first rounded end into engagement with the first end surface; 
 the engaging brings a first portion of the second rounded end into engagement with the second end surface; 
 a combination of the compressing and an operational pressure difference brings a second portion of the first rounded end into engagement with the outboard surface; and 
 the combination of the compressing and an operational pressure difference brings a second portion of the second rounded end into engagement with the inboard surface. 
 
     
     
         14 . The method of  claim 7  applied with inboard and outboard such seals to seal between three members:
 a first member providing the inboard surface for the inboard seal; 
 a second member providing the outboard surface for the inboard seal and the inboard surface for the outboard seal; and 
 a third member providing the outboard surface for the outboard seal. 
 
     
     
         15 . The method of  claim 14  wherein:
 said first member is a tubing hanger; 
 said second member is a spacer; 
 said third member is a wellhead. 
 
     
     
         16 . The method of  claim 7  further comprising engineering the seal, the engineering comprising:
 determining a desired seal response to a fluid pressure difference across the seal in the space, the desired response including an increase in engagement bias of the seal against at least one of the inboard and outboard surfaces; and 
 selecting at least one parameter of shape and orientation of the cross-section to provide the desired response. 
 
     
     
         17 . A sealed joint comprising:
 a first end surface;   a second end surface;   a seal compressed between the first and second end surfaces and having first and second end portions respectively contacting the first and second end surfaces, the first and second end portions offset transverse to a direction of the compression; and   a lateral surface, the seal compressively engaged to the lateral surface and not an opposite lateral surface.   
     
     
         18 . The joint of  claim 17  wherein:
 the lateral surface is an outboard surface. 
 
     
     
         19 . The joint of  claim 17  wherein:
 first and second flanges respectively having the first and second end surfaces are bottomed relative to each other without the seal being bottomed relative to the first and second flanges. 
 
     
     
         20 . The joint of  claim 17  wherein:
 the seal has a circular annular platform; 
 the seal has a cross-section having an exterior perimeter formed as a trapezoid with rounded corners. 
 
     
     
         21 . The joint of  claim 17  wherein:
 the seal has a circular annular platform; 
 the seal has a cross-section having an exterior perimeter formed having first and second parallel sides and first and second rounded ends. 
 
     
     
         22 . A method for sealing a space formed by first and second end surfaces adjacent inboard and outboard surfaces, the method comprising:
 inserting a seal into the space without radial interference inboard or outboard, the seal having a cross-section having an exterior perimeter formed as a trapezoid with rounded corners;   engaging first and second of the corners of the seal cross-section with first and second end surfaces of the space;   compressing the seal between the first and second end surfaces; and   straining the seal to rotate the cross-section of the seal to bias the seal into engagement with said inboard and outboard surfaces of the space.   
     
     
         23 . A single-element bi-directional sealing ring for sealing against fluid pressure in an annulus between the facing concentric surfaces of two bodies, said sealing ring comprising an annular body member with an inclined trapezoidal cross-section. 
     
     
         24 . The scaling ring of  claim 23  in which all corners of said trapezoidal cross-section have a radius feature. 
     
     
         25 . The scaling ring of  claim 23  in which after the system pressure and clamping loads are removed, the sealing ring returns approximately to its original form, so that the joint of which it is a part may be more easily separated for disassembly. 
     
     
         26 . The sealing ring of  claim 23  having a cross-section to diameter ratio sufficient to avoid elastic instability and buckling due to its displacement and loading during installation and in operation. 
     
     
         27 . The sealing ring of  claim 23  in which at least three corners of said trapezoidal cross-section are rounded. 
     
     
         28 . A method for engineering the sealing ring of  claim 23 , the method comprising; determining a desired increase in the radial dimension of the cross-section in proportion to at least one of:
 axial compression of the ring; and   a defined axial force; and   selecting the inclination angle is defined so as to provide said increase.   
     
     
         29 . The sealing ring of  claim 23  formed of a metallic material. 
     
     
         30 . The sealing ring of  claim 23  formed of a non-metallic fiber-reinforced composite material. 
     
     
         31 . The sealing ring of  claim 23  installed between the facing surfaces of the bodies and longitudinally compressed between planar surfaces of a support ring and a loading ring. 
     
     
         32 . The sealing ring of  claim 23  installed between the facing surfaces of the bodies and longitudinally compressed between the bodies. 
     
     
         33 . The sealing ring of  claim 23  installed between the facing surfaces of the bodies and wherein:
 the seal cross-section is shaped and oriented so that an increase in radial span of the cross-section in response to axial loading eliminates radial clearances between the seal and facing surfaces and generates radial compression of the contacting surfaces of the seal cross-section and said bodies effective to create a barrier to the passage of fluid. 
 
     
     
         34 . A bi-directional sealing ring for sealing against fluid pressure in the annulus between the facing cylindrical surfaces of two concentric bodies, said sealing ring comprising an annular body member with an inclined triangular cross-section. 
     
     
         35 . A bi-directional sealing ring for sealing against fluid pressure in the annulus between the facing cylindrical surfaces of two concentric bodies, said sealing ring comprising an annular body member an inclined cross-section of trapezoidal, triangular, or obround exterior perimeter so as to have radially offset first and second longitudinal extremes.