Patent Application
20150101682
The invention pertains to the field of industrial valves. More particularly, the invention pertains to settling tank mud valves.
Mud valves, also referred to as plug drain valves, are generally designed for installation in settling basin lines, waterworks, sewage treatment plants, and other industrial applications. Sediments may build-up over time in tanks or other fluid holding structures, and require periodic flushing and cleaning of the tank. Mud valves are provided in such situations to provide an outlet for sediments and the fluids used to flush them.
Typically, a mud valve is constructed with a frame which forms a flange which mounts on the bottom of a tank, surrounding a hole which mates the valve to a pipe that serves as a drain portal for the sedimentary material being flushed from the tank. The frame is generally annular in shape, its lower surface forming a flange mating surface, and its inner circumference forming a valve seating surface. A yoke is generally bolted to the frame at right angles to support other operative components of the mud valve. A valve plug is mounted in the central portion of the yoke, parallel to the frame, such that it can be moved into contact with the frame, sealing the central portion of the annular frame. As with the inner circumference of the annular frame, the lower surface of the valve plug is provided with a seating surface which mates to the seating surface on the inner circumference of the annular frame. Both seating surfaces may be constructed with specific seating materials such as brass, rubber, or other materials that are conducive to forming a better seal when the valve is closed.
A threaded lift nut is generally mounted in the apex of the yoke and a thrust nut is generally mounted on the top surface of the valve plug. A threaded stem passes through the lift nut and is connected to the valve plug via the thrust nut, such that when the threaded stem is rotated, the stem causes the valve plug to move from a position of contact with the frame where it creates a seal, to a position away from the frame which opens the mud valve and allows sediments and flushing fluids to flow through the center of the annular frame. Alternatively, a stuffing box may be incorporated in the arch of the yoke to hold the stem at a specific height and a lifting nut may be incorporated on the valve plug to move the valve plug vertically along the stem.
To maintain the proper orientation of the valve plug, and to assure that it does not rotate within the yoke, the valve plug is provided with pairs of tabs extending radially from its circumference on opposite sides, each set of tabs sliding along a guide rail on the inner surface of the yoke arms.
The frame, yoke, and valve plug are normally constructed as individual components of cast iron, brass, stainless steel, or other materials which are compatible with the fluids being held in the tank and the structural requirements imposed by the fluid pressures involved.
Multiple tanks are often connected to a common drain line, and flushed at different times, so the mud valve must be sufficiently strong to block potentially substantial back pressure when other tanks are being flushed. As a result the structural integrity of the valve over time is a critical factor in its construction.
Typically, mud valves are assembled by bringing the drain plug and yoke together so that the drain plug tabs can be properly positioned relative to the guide rails on the inner surface of the yoke arms. The end of each arm of the yoke is provided with a flange having bolt holes which are then used to receive bolts which hold the yoke in its operative position relative to the annular frame. This method of construction and assembly has several disadvantages however.
The bolts used to connect the yoke to the annular frame represent a potential failure point, as they may loosen, corrode, or fail for other reasons over time. Similarly, servicing the valve to replace the valve plug or seating surfaces, for example, may also be complicated by corrosion of the yoke attachment bolts, making them difficult to remove when attempting to disassemble the valve so that the valve plug can be removed. And finally, manufacturing cost of mud valves is affected by this assembly method, as the annular frame and yoke are manufactured as separate components through casting or other means and ultimately bolted together, each of these factors creating additional manufacturing steps requiring manpower and materials expenditures.
Accordingly, the present invention provides a mud valve constructed from an annular frame and yoke that are a single, permanently connected unit. Additionally, to allow assembly of the mud valve, the valve plug is provided with pairs of tabs wherein the tabs in each pair are a different distance from the upper side of the valve plug. This construction allows the valve plug to be tilted in two planes so that one pair of tabs may be first aligned with one guide rail on one side of the yoke, and then rotated to bring the second pair of tabs into alignment with the guide rail on the other side of the yoke. Later attachment of the stem through the stuffing box to the lifting nut holds the valve plug in this engaged position for proper operation of the mud valve. Thus, assembly and disassembly of the mud valve is simplified as the yoke and frame do not have to be separated when assembling or disassembling the mud valve.
The yoke and annular frame may be formed from a single casting to reduce manufacturing steps. Alternatively, the yoke and annular frame may be formed as two separate units and welded or otherwise permanently fused together to form a single integrated unitary structure. This method of construction eliminates the potential failure of fasteners connecting the yoke and annular frame and simplifies assembly. Further, future service of the mud valve is simplified as the yoke and annular frame do not have to be separated to remove the valve plug for replacement or repair.
With reference to the drawings, and in particular
A stuffing box 310 through which a threaded stem 400 passes is located at the peak of the yoke 300 and maintains the stem in a fixed vertical position relative to the yoke 300 while still allowing the stem 400 to rotate freely. One end of the threaded stem 400 is coupled to the valve plug 500 by a fitting, for example a lifting nut 510, which allows the threaded stem 400 to rotate and move the valve plug 500 relative to the frame 200. The valve plug 500 is positioned between the yoke 300 arms 320 such that when the valve plug 500 is moved toward the annular frame 200 by turning the threaded stem 400, the lower surface 520 of the valve plug 500 mates with, and seals, the inner circumference 210 of, and space within, the annular frame 200.
The annular frame 200 and yoke 300 are integrated, that is, permanently connected at their intersection 600. This permanent connection may be accomplished by casting the annular frame 200 and yoke 300 as a single unit, milling the two structures from a single piece of material, permanently welding the annular frame 200 and yoke 300 together at their intersection 600, or other means of permanently connecting the two elements into a single unit that does not rely on removable fasteners.
The yoke 300 is provided with guide rails 330 on the inner surface of its arms 320 to maintain the valve plug 500 in its proper orientation when it is moved away from the annular frame 200 by turning the threaded stem 400. The upper side of the body of the valve plug 500 is provided with tabs 530, 531, 532, 533 that slide on either side of the yoke 300 guide rails 330 for this purpose. The tabs 530, 531, 532, 533 are arranged in pairs—a first pair 530 and 531, and a second pair 532 and 533, extending from opposite sides of the valve plug 500. The tabs 530 and 531, 532 and 533 in each pair are separated from each other by a distance such that when the valve plug 500 is in its operational position they form a channel with one tab 530, 531, 532, 533 on each side of the guide rails 330. Further, in each pair of tabs, 530 and 531, 532 and 533, one tab is located a greater distance from the valve plug 500 than the other tab in the set, such that both pairs of tabs have a near tab on the same side of the guide rails, and a far tab on the opposite side of the guide rails. As shown in
The relative position of the tabs 532, 533 on the valve plug 500 is again illustrated in a side view of the valve plug 500 in
Assembly of the valve plug 500 into the yoke 300 is illustrated in
Alternatively, the valve plug 500 can be tilted 90 degrees from its normal operating position, and simultaneously rotated so that both near tabs 530, 532 are in a position to pass between the guide rails 330 as shown in
Regardless of whether the valve plug 500 is inserted according to
Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.
