A floating ball valve comprising: a housing having an internal cavity and first and second fluid flow ports through which fluid flows selectively in either direction from the first to the second or the second to the first fluid flow ports when the valve is open; a floating ball housed in the cavity and formed having a through hole for passage of fluid the ball being rotatable to open the valve and allow fluid flow through the fluid flow ports and internal cavity and to close the valve and block fluid flow through the fluid flow ports and cavity; and a pressure relief valve (PRV) having a cracking pressure mounted to the floating ball so that the PRV communicates with the through hole, and when the floating ball valve is closed the PRV faces and communicates with the first fluid flow port; wherein the PRV is normally closed whether the floating ball valve is open or closed, and when the floating ball valve is closed, if pressure in the internal cavity exceeds the cracking pressure of the PRV, the PRV opens to relieve the pressure.
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