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A ball valve assembly comprises a housing with ball valve rotatably disposed in a valve chamber in the flow passage. The ball valve is rotatable between open and closed positions by a valve stem that is connected to the ball valve at one end. The ball valve has an open ended slot in which the end of

A ball valve assembly comprises a housing with ball valve rotatably disposed in a valve chamber in the flow passage. The ball valve is rotatable between open and closed positions by a valve stem that is connected to the ball valve at one end. The ball valve has an open ended slot in which the end of the stem is received. During assembly the stem may be inserted into the housing first and then the ball valve introduced into the housing with the slot facing the stem and then moved in the direction of the slot so that that the stem is received in the slot. The arrangement enables the conventional bonnet in a ball valve assembly to be eliminated and therefore provides for a compact design.

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What is claimed is: 1. A ball valve assembly comprising a housing defining a flow passage therethrough, a valve chamber in said flow passage, a ball valve rotatably disposed in said valve chamber, the ball valve having a bore therethrough and being rotatable about an axis between an open position i

What is claimed is: 1. A ball valve assembly comprising a housing defining a flow passage therethrough, a valve chamber in said flow passage, a ball valve rotatably disposed in said valve chamber, the ball valve having a bore therethrough and being rotatable about an axis between an open position in which the bore is in fluid communication with the flow passage and a closed position in which the communication is blocked, and a valve stem connected to the ball valve and rotatable about the axis so as to move the ball valve between the open and closed positions, the stem being connected to the ball valve by an end of the valve stem being received in an elongate slot defined in the ball valve, the elongate slot having opposed side walls and a length that extend in a direction substantially along a direction of the bore extending through the ball valve and having an open end opening in a direction transverse to the axis and the open end laterally spaced from the axis for entry or exit of the stem from the slot when the ball valve is moved relative to the stem in the direction of the slot during assembly or disassembly, characterised in that the assembly further comprises a separate stop member for releasable attachment to the ball valve after receipt of the end of the stem in the slot to prevent exit of the end of the stem from the open end of the slot, the stop member located adjacent the open end of the slot laterally spaced from the axis and laterally offset to one side of the stem. 2. A ball valve assembly according to claim 1, wherein said end of the valve stem is a key with an actuating surface for abutment with a corresponding surface on the slot. 3. A ball valve assembly according to claim 2, wherein the actuating surface and the corresponding surface are substantially flat. 4. A ball valve assembly according to claim 1, wherein the slot is elongate and extends from the open end at a surface of the ball to a location at or near the axis of rotation of the ball valve. 5. A ball valve assembly according to claim 1, wherein the stem is connected to the ball valve at the axis of rotation. 6. A ball valve assembly according to claim 1, wherein the ball valve is supported for rotation by a trunnion. 7. A ball valve assembly according to claim 6, wherein the trunnion is defined on the ball valve and is received in a trunnion bearing. 8. A ball valve assembly according to claim 7, wherein the trunnion bearing is defined in a trunnion support plate. 9. A ball valve assembly according to claim 8, wherein the trunnion support plate is separable from the housing. 10. A ball valve assembly according to claim 1, wherein the stem is disposed in a stem bore in the housing, the stem bore extending substantially perpendicular to the flow passage. 11. A ball valve assembly according to claim 10, wherein the stem has a shoulder defined thereon and the stem bore has a corresponding shoulder defined therein, the shoulders preventing movement of the stem out of the stem bore. 12. A ball valve assembly according to claim 11, wherein the shoulder on the stem is defined by an annulus formed on the stem. 13. A ball valve assembly according to claim 11, wherein the shoulder in the stem bore is defined by a counter bore where the stem bore meets the valve chamber. 14. A ball valve assembly according to claim 1, wherein the stem extends in a direction substantially perpendicular to the length of the slot. 15. A ball valve assembly according to claim 1, wherein the stop member does not pass through the stem. 16. A ball valve assembly comprising a housing defining a flow passage therethrough, a valve chamber in said flow passage, a ball valve rotatably disposed in said valve chamber, the ball valve having a bore therethrough and being rotatable about an axis between an open position in which the bore is in fluid communication with the flow passage and a closed position in which the communication is blocked, and a valve stem connected to the ball valve and rotatable about the axis so as to move the ball valve between the open and closed positions, the stem being connected to the ball valve by an end of the valve stem being received in an elongate slot defined in the ball valve, the elongate slot having opposed side walls and a length that extend in a direction substantially along a direction of the bore extending through the ball valve and having an open end opening in a direction transverse to the axis and the open end laterally spaced from the axis for entry or exit of the stem from the slot when the ball valve is moved relative to the stem in the direction of the slot during assembly or disassembly, characterised in that the assembly further comprises a separate stop means for releasable attachment to the ball valve after receipt of the end of the stem in the slot and for preventing movement of the ball and slot relative to the stem to prevent exit of the end of the stem from the open end of the slot, wherein the stop means extends in a direction transverse to the slot and to one side of the stem. 17. A ball valve assembly according to claim 16, wherein the stop means is received in a transverse bore in at least one side wall of the slot adjacent the open end of the slot laterally spaced from the axis and laterally offset to one side of the stem. 18. A ball valve assembly according to claim 17, wherein the stop means is threadedly engaged with said transverse bore. 19. A ball valve assembly according to claim 16, wherein the stop means is a pin. 20. A ball valve assembly according to claim 17, wherein there is provided a transverse bore in each of the opposed side walls of the slot. 21. A ball valve assembly according to claim 16, wherein the stop means does not pass through the stem. 22. A method for assembling a ball valve assembly, the assembly comprising a housing defining a flow passage therethrough and a substantially perpendicular stem bore, a valve chamber in said flow passage, a ball valve rotatably disposed for rotation about an axis in said valve chamber, the ball valve having a bore therethrough and an elongate slot with an open end opening in a direction transverse to the axis, the elongate slot having opposed side walls and a length that extend in a direction substantially along a direction of the bore extending through the ball valve, the ball valve having a valve stem, the method comprising the steps of inserting the stem from the valve chamber into the stem bore and then inserting the ball valve through the flow passage and into the valve chamber, presenting the open end of the slot to an end of the stem and moving the ball valve in a direction substantially parallel to the length of the slot and transverse to the axis so that the end of the stem passes through the open end and along the length of the slot, characterised in that a separate stop member is provided and the method further comprises inserting the stop member at a location adjacent the open end of the slot after the end of the stem has passed along the slot such that the stop member prevents movement of the stem out of the open end of the slot, the stop member laterally spaced from the axis and laterally offset to one side of the stem. 23. A method according to claim 22, wherein the stop member is inserted into at least one transverse bore. 24. A method according to claim 22, wherein the stop member is inserted so that it extends across the slot. 25. The method according to claim 22, wherein the stop member does not pass through the stem.