A decoking system comprising a decoking control valve comprising a piston a cylinder, a first outlet port and a second outlet port; wherein the piston moves along a direction of travel within the cylinder and is configured to allow decoking fluid to flow in from an inlet port and out of either the first outlet port or the second outlet port; characterized in that the decoking control valve comprises: two sets of hydraulic rod seals and guide rings formed within a wall of the cylinder; one set of a hydraulic rod seal and guide ring working in cooperation with the first outlet port, the other set of a hydraulic rod seal and guide ring working in cooperation with the second outlet port, and wherein each guide ring is spaced axially relative to a respective one of the two hydraulic rod seals; and at least one drilled port formed in the piston to equalize pressure across a respective one of the two sets of hydraulic rod seals and guide rings immediately before the piston is retracted from contact therewith as the piston traverses the direction of travel within the cylinder; wherein: the cylinder houses the hydraulic rod seals within a groove of the cylinder adjacent to the piston; the hydraulic rod seals comprise a seal ring which engages the piston, wherein the seal rings are energized by an activator; and as the piston travels within the cylinder, the seal ring is energized at one outlet port (191, 192) at a time to allow fluid to flow out of another one or more outlet ports (191, 192). the piston moves along a direction of travel within the cylinder and is configured to allow decoking fluid to flow in from an inlet port and out of either the first outlet port or the second outlet port; characterized in that the decoking control valve comprises: two sets of hydraulic rod seals and guide rings formed within a wall of the cylinder; one set of a hydraulic rod seal and guide ring working in cooperation with the first outlet port, the other set of a hydraulic rod seal and guide ring working in cooperation with the second outlet port, and wherein each guide ring is spaced axially relative to a respective one of the two hydraulic rod seals; and at least one drilled port formed in the piston to equalize pressure across a respective one of the two sets of hydraulic rod seals and guide rings immediately before the piston is retracted from contact therewith as the piston traverses the direction of travel within the cylinder; wherein: two sets of hydraulic rod seals and guide rings formed within a wall of the cylinder; one set of a hydraulic rod seal and guide ring working in cooperation with the first outlet port, the other set of a hydraulic rod seal and guide ring working in cooperation with the second outlet port, and wherein each guide ring is spaced axially relative to a respective one of the two hydraulic rod seals; and at least one drilled port formed in the piston to equalize pressure across a respective one of the two sets of hydraulic rod seals and guide rings immediately before the piston is retracted from contact therewith as the piston traverses the direction of travel within the cylinder; wherein: the cylinder houses the hydraulic rod seals within a groove of the cylinder adjacent to the piston; the hydraulic rod seals comprise a seal ring which engages the piston, wherein the seal rings are energized by an activator; and as the piston travels within the cylinder, the seal ring is energized at one outlet port (191, 192) at a time to allow fluid to flow out of another one or more outlet ports (191, 192).