Patent EA-000718-B1 (EA)
Title: Dual plate check valve
Inventor: BECKETT KIM STUART
IPC: F16K25/00
Filed: 1997-07-29
Abstract: 1. A dual plate check valve comprising: a substantially cylindrical valve body (10) provided with a diametrical cross-member (14) thereby defining a pair of substantially D-shaped apertures and two substantially D-shaped plates (18), pivotally connected by a hinge means (20) parallel to said cross-member (14), and pivotable between a valve open position and a valve closed position in which a sealing face portion of each plate (18) engages a sealing face portion provided on a valve seat (16) which surrounds each aperture, wherein the sealing face portions on each of the plates (18) and/or on each of the valve seats (16) has a groove (52) filled with a weld inlay (40, 42). 2. A valve according to claim 1, wherein said weld inlay (40, 42) is 1 mm to 15 mm wide. 3. A valve according to claim 1 or 2, wherein said weld inlay is 0.01 to 10 mm thick. 4. A valve according to claim 1, 2 or 3, wherein said weld inlay (40, 42) is 0.5 mm to 5mm thick. 5. A valve according to claim 1, 2, 3 or 4 wherein said grooves (52) are substantially semi-circular, rectangular, U-shaped, V-shaped or dovetail in transverse cross-section. 6. A valve according to any one of the preceding claims, wherein each weld inlay (40, 42) comprises Stellite, stainless steel. Monel or Inconel. 7. A valve according to any one of the preceding claims, provided with weld inlays (40, 42) on both of the valve plates (18) and valve seats (16), the inlays (42) on the plates (18) being located so as to contact corresponding inlays (40) on the valve seats (16) when the valve is in the closed position. 8. A valve according to claim 7, wherein the inlays (42) on the plates (18) are wider than those (40) on the seats (16) or vice versa. 9. A valve according to any one of the preceding claims, wherein each or at least one weld inlay (40, 42) is finished flush with the respective adjacent body or plate face.  10. A valve according to any one of the preceding claims, wherein each or at least one weld inlay (40, 42) is finished proud on one or both sides. 11. A valve according to any one of the preceding claims, including plates (18) comprising a reinforced central portion (I8A) and non-reinforced portions (18B) adjacent to each end of the straight line of the D. 12. A high pressure fluid line assembly including at least one valve according to any one of claims 1 to 11. 13. A cryogenic fluid line assembly including at least one valve according to any one of claims 1 to 11. 14. A high temperature fluid line assembly including at least one valve according to any one of claims 1 to 11. 15. A method of forming a valve sealing face portion of a sealing surface of the plates (18) and/or valve seats (16) of a dual plate check valve having a substantially cylindrical valve body (10) provided with a diametrical cross-member (14) thereby defining a pair of substantially D-shaped apertures, and two substantially D-shaped plates (18) , pivotally connected by a hinge means (20) parallel to said cross-member (14), and pivotable between a valve open position and a valve closed position in which the sealing face portion of each plate (18) engages a sealing face portion provided on a valve seat (16) which surrounds each aperture, the method including the steps of: (a) providing a groove (52) in the or each sealing surface; (b) forming a weld inlay (54) in said groove (52). 16. A method according to claim 15, wherein step (b) further comprises forming said inlay by welding so that the weld inlay protrudes above the top of the groove. 17. A method according to claim 15 or 16, further comprising the step of finishing or the each weld inlay flush with its respective sealing surface. 18. A method according to claim 15 or 16, further comprising the step of finishing or the each weld inlay proud on one or both sides. 19. A method according to any one of claims 15 to 18, wherein said groove (52) is 1 mm to 15 mm wide. 20. A method according to any one of claims 15 to 19, wherein said groove (52) is 0.5 mm to 5 mm deep. 21. A method according to any one of claims 15 to 20, wherein said groove (52) is substantially semicircular, rectangular, U-shaped, V-shaped or dovetail in transverse cross-section. 22. A method according to any one of claims 15 to 21, wherein said at least one valve component is cast or forged with an integral said groove. 23. A method according to any one of claims 15 to 22, wherein said weld inlay (54) comprises Stellite, stainless steel, Monel or Inconel. 24. A D-shaped valve plate (18) comprising a sealing face portion for engaging an opposing sealing face portion provided on a valve seat (16), wherein said sealing face portion on the plate has a groove (52) filled with a weld inlay (42).