O-ring seal system for metal, thermoplastic and fiber reinforced plastic flanges

Abstract

An O-ring seal system for pipe flanges having a backing ring, an O-ring seal positioned within the backing ring, and a vacuum ring positioned within the O-ring seal. The backing ring and the vacuum ring form a rigid base against which mating flanges on pipes can be bolted together, thereby preventing bending of the mating flanges and permitting flange bolts to be torqued to their full tensile load limit without damage to the mating flanges. The O-ring seal system is constructed so that the O-ring seal is retained between the mating flanges without the need to position the O-ring seal in a groove in one of the mating flanges. Bending of the flanges is minimized since the flanges are clamped against the backing ring, minimizing stresses due to bending, thereby extending the service life of the flanges.

We claim: 
     
         1 . An O-ring seal system for plastic pipe flanges, comprising:
 a backing ring having openings therein to receive bolts therethrough;   an elastomeric O-ring seal positioned within said backing ring;   a vacuum ring positioned within said elastomeric O-ring seal;   said backing ring and said vacuum ring forming a rigid base against which mating plastic pipe flanges on pipes can be bolted together, thereby preventing bending of said mating plastic pipe flanges and permitting flange bolts to be torqued to their full tensile load limit without damage to said mating plastic pipe flanges; and   said O-ring seal system being constructed so that said elastomeric O-ring seal is retained between said mating plastic pipe flanges without the need to position said elastomeric O-ring seal in a groove in one of said mating plastic pipe flanges.   
     
     
         2 . The O-ring seal system according to  claim 1 , wherein said backing ring has a thickness constructed to compress said elastomeric O-ring seal to an optimum sealing stress without over stressing said elastomeric O-ring seal. 
     
     
         3 . The O-ring seal system according to  claim 1 , wherein said vacuum ring is constructed to prevent said elastomeric O-ring seal from being displaced or pulled out of said mating plastic pipe flanges when a vacuum condition occurs in said pipes. 
     
     
         4 . The O-ring seal system according to  claim 1 , wherein said elastomeric O-ring seal is constructed to provide a single point of line contact with said mating plastic pipe flanges so that slight flange waviness or lack of flatness in said mating plastic pipe flanges will not result in leakage. 
     
     
         5 . The O-ring seal system according to  claim 1 , wherein said elastomeric O-ring seal is circular, oval, rectangular, D-shaped, polygon-shaped, or C-shaped. 
     
     
         6 . The O-ring seal system according to  claim 1 , wherein said elastomeric O-ring seal has a hollow interior. 
     
     
         7 . The O-ring seal system according to  claim 6 , wherein said elastomeric O-ring seal has one or more vents extending from said hollow interior to an inner circumference of said elastomeric O-ring seal. 
     
     
         8 . An O-ring seal system for plastic pipe flanges, comprising:
 a backing ring having openings therein to receive bolts therethrough;   an elastomeric O-ring seal positioned within said backing ring;   a vacuum ring positioned within said elastomeric O-ring seal;   said backing ring and said vacuum ring forming a rigid base against which mating plastic pipe flanges on pipes can be bolted together, thereby preventing bending of said mating plastic pipe flanges and permitting flange bolts to be torqued to their full tensile load limit without damage to said mating plastic pipe flanges;   said O-ring seal system being constructed so that said elastomeric O-ring seal is retained between said mating plastic pipe flanges without the need to position said elastomeric O-ring seal in a groove in one of said mating plastic pipe flanges;   said vacuum ring constructed to prevent said elastomeric O-ring seal from being displaced or pulled out of said mating plastic pipe flanges when a vacuum condition occurs in said pipes; and   said elastomeric O-ring seal constructed to provide a single point of line contact with said mating plastic pipe flanges so that slight flange waviness or lack of flatness in said mating plastic pipe flanges will not result in leakage.   
     
     
         9 . The O-ring seal system according to  claim 8 , wherein said backing ring has a thickness constructed to compress said elastomeric O-ring seal to an optimum sealing stress without over stressing said elastomeric O-ring seal. 
     
     
         10 . The O-ring seal system according to  claim 9 , wherein said elastomeric O-ring seal is circular, oval, polygon-shaped, or C-shaped. 
     
     
         11 . The O-ring seal system according to  claim 10 , wherein said elastomeric O-ring seal has a hollow interior. 
     
     
         12 . The O-ring seal system according to  claim 11 , wherein said elastomeric O-ring seal has one or more vents extending from said hollow interior to an inner circumference of said elastomeric O-ring seal.