a sliding sleeve valve and method for assembly is disclosed . the valve comprises a segmented main body that is assembled from a top , middle and bottom segments . the middle segment has flow apertures . a closing sleeve is co - axially mounted in the assembled main body . the closing sleeve has flow apertures that are intended to communicate with the flow apertures of the middle section when the valve is open . the closing sleeve is sealed by seal means within the main body to prevent undesired fluid flow across the valve . the seal means comprise primary , secondary and tertiary seals acting in cooperative combinations . the seals comprise o - ring and vee - stack seals located within the body of the valve . the sliding sleeve valve has a fluid pressure equalization means to permit equalization of fluid pressure across the valve before it is fully opened or fully closed in order to reduce wear on the seals . the equalization means comprises a plurality of pressure equalization ports in the sliding sleeve that are intended to communicate with the main body apertures prior to the sliding sleeve apertures when opening and subsequent to the sliding sleeve apertures when closing .