Flanged Connection for Flow Line Members

This invention relates to an improved means and method for connecting valves and the like to adjacent conduits, and more particularly to such improved means and methods utilizing a separate bolting ring threaded onto an end hub of the valve for connecting the valve to the conduit.

Heretofore, such as illustrated in FIG. 1A herein, a separate bolting ring has been utilized for connecting an end hub of a valve to a flow line or conduit. However, with such an arrangement, it has been difficult to obtain precise and accurate positioning of the ring onto the hub. Further, upon relative high torques exerted by higher excessive bolting forces against the bolting ring, the thread area adjacent the flow line is placed under an undesirable compressive loading.

One possible solution to the precise positioning of a bolting ring on the externally threaded hub has involved the use of interference threads on the hub and bolting ring. However, this has tended to be unsatisfactory as it is difficult to install a bolting ring with an interference thread, and if the bolting ring is heated and then inaccurately positioned on the hub, the ring is fixed at that location unless removed by difficult procedures.

Also, if the threaded connection is slightly loose after heating of the bolting ring, and subsequent cooling, the bolting ring may rotationally deform under subsequent excessive bolting torques.

The present invention is directed to an improved means and method for connecting a valve hub to an associated flow line or conduit utilizing a separate bolting ring threaded onto an externally threaded valve hub. The separate bolting ring has a central bore therethrough defined by a threaded end portion adjacent the valve, and an opposed smooth end portion adjacent the associated conduit extending radially inwardly of the threaded end portion. The valve hub has a mating externally threaded end portion and an adjacent mating smooth end portion recessed radially inwardly of the externally threaded end portion. The smooth end portions of the valve hub and bolting ring define facing shoulders extending at right angles to the smooth portions and contacting each other during assembly of the bolting ring onto the hub for accurate positioning of the bolting ring.

Upon assembly of the bolting ring onto the valve hub with straight cylindrical mating threads, the mating threads first engage and after rotation of the bolting ring around one turn, the adjacent smooth surfaces of the hub and holting ring preferably engage each other in a slight interference fit after being guided by the mating screw threads. Upon the positioning of the stud and nut combination within axially aligned openings of the bolting ring and adjacent conduit flange, the nuts are tightened to draw the bolting ring and conduit flange together. The tightening of the nuts results in a torque force erected against the bolting ring to produce a generally uniform peripheral force about the contacting surfaces of the hub and bolting ring to provide an increased interference fit between the smooth surfaces while relieving the threaded fit at the end of the bolting ring adjacent the valve. Such an arrangement permits a simplified assembly of a separate bolting ring having a relatively high yield strength onto an externally threaded valve hub having a relatively low yield strength by engagement of smooth mating cylindrically surfaces on the hub and ring while utilizing straight cylindrical mating threads thereby minimizing damage or overstressing of the thread connection. Further, contacting shoulders formed adjacent the mating smooth portions permit accurate positioning of the bolting ring onto the valve hub.

In addition, the high bolting torque resulting from tensioning the studs is transmitted by the smooth surfaces to the valve hub thereby minimizing stressing of the threaded connection.

It is an object of this invention to provide an improved means and method for connecting valves to adjacent conduits utilizing a separate bolting ring threaded onto an externally threaded end hub of the valve.

A further object of the invention is to provide such an improved means and method in which the bolting ring and associated valve hub are formed with mating screw threads which are initially engaged and with adjacent mating stepped smooth surface portions at the ends thereof remote from the valve which transfer high bolting torques to the valve hub thereby minimizing stressing of the threaded connection.

A further object of the invention is to provide such improved means and method in which the bolting ring may be precisely positioned on the externally threaded valve hub at a predetermined precise position without any undue stressing of the mating threads on the bolting ring and valve hub.

An additional object is to provide a connection for a bolting ring and valve hub utilizing mating cylindrical smooth portions adjacent the ends thereof remote from the valve, and mating straight cylindrical threaded portions at the ends thereof adjacent the valve which are engaged upon assembly prior to engagement of the mating smooth portions.

Other objects, features, and advantages of the invention will become more apparent after referring to the following specification and drawings.

FIG. 1A is an example of the Prior art illustrating a bolting ring threaded onto an externally threaded valve hub;

FIG. 1 is a longitudinal sectional view of a valve connected to opposed conduits by the threaded bolting rings and valve hubs forming the present invention;

FIG. 2 is an exploded view showing the bolting ring removed from the valve hub of FIG. 1;

FIG. 3 is a sectional view showing the bolting ring partially threaded on to the valve hub during assembly of the connection;

FIG. 4 is a sectional view similar to FIG. 3 but showing the bolting ring in assembled position on the valve hub; and

FIG. 5 is a sectional view of the assembled bolting ring and valve hub illustrating in exaggerated relation the torque exerted upon tensioning of the connecting studs with a compressive peripheral force therefrom being exerted against the smooth contacting surfaces of the bolting ring and valve hub.

Referring now to the drawings for a better understanding of this invention and more particularly to FIG. 1, a valve is shown generally at 10 forming a flow line member having a valve body shown generally at 12 with a fluid passage 14 therethrough. A ball valve member shown at i& is mounted for movement between open and closed positions relative to fluid passage 14. A stem 18 has a handle 20 connected thereto for rotating ball valve member is between open and closed positions as well known in the art.

Valve body 12 has opposed end hubs indicated generally at 22 thereon defining annular end faces 24. Opposed conduits or flow line members 26 are connected to valve 10 and have annular end faces 28 in opposed relation to end faces 24 of valve hubs 22. Annular gaskets 30 are positioned between annular end faces 24 and 28 for providing a fluid tight seal between faces 24 and 28. End flanges 32 on conduits 26 have a plurality of openings 34 equally spaced about flange 32.

For connecting conduits 26 in abutting relation to end hub 22, and forming an important part of this invention, a bolting ring is shown generally at 36 for each end hub 22. Openings 38 in bolting ring 36 are positioned to be in axial alignment with openings 34 of flange 32 on the associated conduit 26. Suitable stud and nut combination indicated generally at 40 comprising threaded studs or pins and nuts 44 are received within aligned opening 34,38 and upon tightening, gasket 30 forms a fluid tight sealing relation with end faces 24,28.

Referring now to FIG. 2, end hub 22 has an externally threaded inner end portion 46 defining the inner end adjacent valve 16, and an outer end portion 48 defining a smooth cylindrical surface adjacent the outer end of hub 22 remote from valve 16. Smooth cylindrical surface 48 is recessed radially inwardly from the screw threads on end portion 46 and defines an annular shoulder 50 formed between the screw threads of end portion 46 and smooth portion 48. Smooth end portion 48 has an inner smooth section 60 which is adapted to contact bolting ring 36 in a similar relation and an adjacent smooth section 62 which is recessed radially inwardly from smooth section 60 and extends outwardly from locking ring 36 in assembled relation as will be explained further. The diameter of smooth section 62 may be smaller than that of smooth section 60 by a small amount, and in particular it will be slightly smaller than smooth portion 68 on bolting ring 36. In FIG. 2 the difference in diameters between smooth sections 60 and 62 have been exaggerated to a great degree, whereas in practice the difference will only be a few thousandths of an inch. The width of threaded end portion 46 is shown at A and the width of smooth cylindrical end portion 48 is shown as D. The inner end smooth section 60 has a width shown at B while the outer smooth end section 62 has a width shown at C.

Bolting ring 36 has a central bore therethrough defined by an inner threaded end portion 64 adjacent valve member 16 and a flange 66 on the opposite end of bolting ring 36 which extends radially inwardly of threaded end portion 64. Flange 66 forms a smooth cylindrical end portion 68 and a shoulder 70 extending at right angles to smooth surface 68 joins threaded portion 64 and smooth surface portion 68.

Referring now particularly to FIG. 2, the width of threaded end portion 64 is shown at E and the width of cylindrical smooth portion 68 is shown at F. For best results, width F is around 25% of width E but satisfactory results may be obtained with width F being between around 15% and 45% of width E dependent on such factors as the entire thickness of bolting ring 36. Width F is of a minimum of one-eighth inch (1/8") and as high as around one-half inch (1/2") with the thickness of bolting ring 36 being around two inches.

For ease of assembly, the relationships between dimensions A, B, C and n on the hub and dimension E and F of the bolting ring should be such that width A and width E should be approximately the same, and the width E should be greater than width B by at least the width of one thread turn, so that upon assembling ring 36 onto hub 14 the thread is fully engaged prior to the interfering smooth sections 60 and 68 coming into engagement.

For assembly of bolting ring 36 onto hub 22, the following step are employed. First, the straight cylindrical threads of bolting ring 36 and hub 22 are engaged and ring 36 is rotated at least around one turn onto hub 22 and preferably several turns. Then, upon further rotation of ring 36, smooth surfaces 60 and 68 engage as shown in FIG. 3 with bolting ring 36 being rotated thereon until shoulder 50 contacts shoulder 70. Ring 36 will turn freely on hub 22 so long as only threaded portions 36 and 46 are engaged, and will turn with more difficulty when interfering portions 60 and 68 become engaged. If ring 36 is heated while hub 22 remains cool, then ring 36 may be fully engaged with relative ease. When both hub 22 and ring 36 reach the same temperature, there will be a degree of interference between smooth surfaces 60 and 68, which will provide a smooth contact for the uniform flow of forces between ring 36 and hub 22 as well as sufficient friction to prevent inadvertent rotation of ring 36 relative to hub 22. After contact of shoulders 50 and 70, bolting ring 36 is rotated in a reverse direction a relatively small amount, such as around between 5.degree. and 25.degree. of rotation, to position openings 38 at the proper position relative to openings 34 of flange 32 which have been positioned at precise predetermined locations. Thus, shoulders 50 and 70 are utilized to accurately position bolting ring 36 relative to hub 22 and flange 32. Smooth surface 60 is received within smooth surface 68 with a slight interference fit upon threading of bolting ring 36 onto hub 22. In this relation, valve 10 may be shipped to a location where the valve is connected to flanges 32 of conduits 26 with the stud and bolt combinations 40. Upon installation of valve 10 within a flow line defined by conduits 26, openings 38 are aligned with openings 34 in flanges 32 of the conduit 26. Then, stud and nut combinations 40 are inserted and nuts 44 are tightened to tension threaded studs or pins 42. As shown in FIG. 5 in an exaggerated relation, the tensioning of studs 42 effects a torque and the inner end of bolting ring 36 is urged inwardly to exert a compressive peripheral loading of smooth surface 68 against smooth surface 60. As a result, opposed outer end of bolting ring 36 tends to be urged away from hub 22. Thus, the loading resulting from tensioning of studs 42 is transmitted to the hub 22 and the screw threads along surfaces 46 and 64 are not overstressed.

As a result of the improved connection, end hub 22 may be formed of a steel material less than around 35,000 psi yield strength while bolting ring 36 may be formed of a steel around 45,000 psi yield strength or greater. A relatively low strength material may be utilized for hub 22 as the threaded connection between locking ring 36 and threaded hub 22 is not unduly stressed and any undesirable torque loads are transmitted primarily through the contacting smooth surfaces 62 and 68 to hub 22.

It is pointed out that the threaded connection between hub 22 and ring 36 is outside any wetted surface or lading within fluid passage 14. Further, no additional connections are required between valve member 16 and hub 22 as a result of the present invention.

Referring to FIG 1A, an example of the prior art is illustrated in which a bolting ring shown generally at R is threaded onto an externally threaded valve hub H. It is noted that there is no means for accurately positioning or locating locking ring R on hub H. Further, any torque loading resulting from tensioning of the nut and bolt combinations would be exerted against the threaded connection between hub H and ring R thus possibly resulting in an over-stressing of the threaded connection.

As a preferred embodiment of the present invention has been illustrated, it is apparent that modifications and adaptations of the preferred embodiment will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention as set forth in the following claims.