Integrated pressure balancing system in ball valve

1 . A valve comprising:

a ball coupled to a stem which is turnable by an operator element, said ball being formed with a flow passage and said ball being sealed in a valve seat by means of seals; and

wherein said stem comprises a bypass structure, which upon rotation of said stem, is alignable with an upstream diverging tube and with a downstream diverging tube to allow bypass fluid flow from said upstream diverging tube to said downstream diverging tube for balancing a difference in pressure between upstream and downstream portions of said valve,

and wherein said stem comprises a ball key portion which couples with a keyway aperture formed in an interface member extending from said ball, and said ball key portion is shaped to allow free rotation of said stem with respect to said keyway aperture through a rotation angle α, and wherein said ball key portion comprises a pair of relatively long flat faces that are inclined so a width of said ball key portion is widest at a center of a long side of said ball key portion, and a pair of relatively short flat faces that are inclined so a length of said ball key portion is longest at a center of a short side of said ball key portion.

2 . The valve according to claim 1 , wherein an outer diameter of said ball and a diameter of said flow passage are such that when said ball is turned 90° minus a rotation angle α from a fully open position, said ball is closed to flow therethrough, and said bypass structure is aligned with said upstream diverging tube and with said downstream diverging tube upon rotation of said stem through said rotation angle α.

3 . The valve according to claim 1 , wherein said bypass structure comprises an indentation formed on said stem, said indentation having a surface which is radially inwards of an outer contour of said stem.

4 . The valve according to claim 1 , wherein when said flow passage of said ball is open to flow, said bypass structure blocks the bypass fluid flow from said upstream diverging tube to said downstream diverging tube.

5 . A valve comprising:

a ball coupled to a stem which is turnable by an operator element, said ball being formed with a flow passage and said ball being sealed in a valve seat by means of seals; and wherein said stem comprises a bypass structure, which upon rotation of said stem, is alignable with an upstream diverging tube and with a downstream diverging tube to allow bypass fluid flow from said upstream diverging tube to said downstream diverging tube for balancing a difference in pressure between upstream and downstream portions of said valve, wherein said bypass structure is positioned between, and is rotatable to align with, a pair of bypass pistons which are arranged to slide inside bypass tubes, one of said bypass tubes being an upstream bypass tube which is in fluid communication with said upstream diverging tube, and another one of said bypass tubes being a downstream bypass tube which is in fluid communication with said downstream diverging tube, and wherein each of said pistons is urged by a biasing device towards said stem.

6 . The valve according to claim 5 , wherein when said pistons abut against an outer contour of said stem and not against said bypass structure, said pistons seals said bypass tubes so the bypass fluid flow cannot flow from said upstream diverging tube to said downstream diverging tube.

7 . The valve according to claim 5 , wherein when said pistons abut against said bypass structure, said pistons do not seal said bypass tubes so the bypass fluid flow can flow from said upstream diverging tube to said downstream diverging tube.

8 . The valve according to claim 7 , wherein when said pistons abut against said bypass structure, the bypass fluid flow leaks out of said upstream bypass tube and circulates in an area around said stem and enters said downstream bypass tube and then exits through said downstream diverging tube.

9 . A valve comprising:

a ball coupled to a stem which is turnable by an operator element, said ball being formed with a flow passage and said ball being sealed in a valve seat by means of seals; and wherein said stem comprises a bypass structure, which upon rotation of said stem, is alignable with an upstream diverging tube and with a downstream diverging tube to allow bypass fluid flow from said upstream diverging tube to said downstream diverging tube for balancing a difference in pressure between upstream and downstream portions of said valve, wherein when said flow passage of said ball is open to flow, said bypass structure permits the bypass fluid flow from said upstream diverging tube to said downstream diverging tube.