Low dead space ring

#This invention pertains to the valve art, and, more particularly, ball valves. The invention is particularly applicable to a new and improved ball valve incorporating a low dead space ring and will be described with particular reference thereto. However, it will be appreciated that the invention has broader applications and could be adapted to use in other types and styles of valves.

#Commonly assigned U.S. Pat. Nos. 3,894,718 and 4,410,165 detail the evolution and development of seal assemblies utilized in ball valves, the disclosures of which are hereby incorporated by reference. Generally, early developments of valve seat assemblies for ball valves employed an elementary seat design which included a pair of annular plastic seats that were compacted between the ball member and the wall portions of end fittings. Such seat designs suffered from a number of problems including low sealing forces at low pressure or vacuum conditions, and valve leakage due to wear and tolerance errors.

#These early seat designs gave way to a contoured seat design in which the ball member was engaged along its outer periphery by a narrow band or line contact. Wear problems also developed with contoured seat designs and they gave way to the development of the flexible seat. The flexible seat, though, only provided improved operation for short periods of time. A seat ring with a disc spring, as well as an upstream seat bypass arrangement, were other improvements developed by the industry which progressively overcame various problems associated with ball valve seating arrangements. The U.S. Pat. No. 4,410,165 describes a seal assembly which includes a support ring, a disc spring, and a seat ring. This assembly provides additional seat ring support in a floating ball type of valve which is applicable to use in high fluid pressure environments. A longer life span was, in turn, realized at a cost savings with respect to other known seating arrangements.

#The invention may take physical form in certain parts and arrangement of parts, preferred and alternate embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein:

#FIG. 1 is a side elevational view in partial cross-section of a ball valve construction which incorporates the subject invention;

#FIG. 2 is an enlarged partial view of the ball valve shown in FIG. 1 at an area thereof adjacent a seat assembly;

#Referring now to the drawings wherein the showings are for purposes of illustrating preferred and alternate embodiments of the invention only and not for purposes of limiting same, FIG. 1 shows a ball valve A having a pair of seal assemblies B disposed on opposite sides of a floating-type spherical ball or valve member C. The ball member is adapted for selective rotation between valve closed and open positions as is well known in the art.

#In FIG. 1, the ball valve A includes a body or housing 10 having a central opening extending therethrough defining a valve chamber 12. A pair of end fittings 14, 16 are situated at opposed ends of the body 10 and include a pair of shoulders 18, 20 defined by end faces 22, 24 of the end fittings. The end fittings are secured to the body by conventional means such as elongated tie bolts 26 and are adapted for retaining the seal assemblies B in generally mating arrangement with the ball valve A. One of ordinary skill in the art will appreciate that through openings (not shown) are included in the respective end fittings generally along longitudinal axis 1 of the valve body to accommodate fluid communication between the valve chamber and an external fluid system or associated piping in a known manner. A pair of grooves 28, 30 at opposite ends of the body are open axially toward the end fittings and radially toward the seal assemblies and receive seal members 32, 34 such as O-rings or the like. In this manner, the end fittings and seal assemblies may be placed in sealed relationship with the valve body 10.

#A ball member 36 is dimensioned for close receipt within the valve chamber 12, occupying a major portion of the chamber, and includes an axial passage 38 formed therethrough. The ball member is adapted for selective rotation about a stem axis m to align the passage 38 with the respective through openings formed in the end fittings. As is known, a spade portion of a stem 40 is operatively received in a slot or groove 42 formed in the ball member. The stem penetrates through the side wall of the body and includes a radially extending flange 44 (FIG. 2) cooperable with a recessed or counterbalanced area 46 formed in the body to prevent removal of the stem outwardly from the body along stem axis m. In addition, flange 44 provides a lower support for a thrust washer 48.