CA2006312C

CA2006312C - Stabilized connector flange and method for interconnecting an instrumentmanifold with an orifice plate assembly

Info

Publication number: CA2006312C
Application number: CA 2006312
Authority: CA
Inventors: Spencer M. Nimberger
Original assignee: Precision General Inc
Current assignee: PGI International Ltd
Priority date: 1989-04-07
Filing date: 1989-12-21
Publication date: 1997-12-16
Anticipated expiration: 2009-12-21
Also published as: CA2006312A1; US4920626A

Abstract

Improved methods and apparatus are provided for structurally interconnecting an instrument manifold with a differential pressure assembly having a pair of tapered NPT
threaded outlet ports each adjoining an exterior body surface. First and second connector flanges are provided each having a through passageway for transmitting a pressure signal from the corresponding NPT outlet port in the differential pressure assembly to an inlet port in an instrument manifold. Each connector flange includes a tapered threaded end, a flange end, and a threaded portion fixed between the threaded end and the flange end. The apparatus also includes first and second stabilizer members, and first and second tensioning nuts for exerting a compressive force on the stabilizer members such that the stabilizer members will transmit substantially all radially-directed forces to the differential pressure assembly.
According to the method of the present invention, each connector flange is rotated for obtaining sealing engagement between each connector flange and a respective port in the differential pressure assembly, and the one or more apertures in the flange end are rotated to a preselected rotational position prior to tightening the tension nuts for exerting force on the stablizer members.

Description

~O~G312 1. Field of the Invention The present invention relateq to connector flanges for structurally interconnecting an instrument manifold with a differential pre~sure assembly and, more particularly, relates to connector flange3 which reliably provide independent structural interconnection of an orifice plate a3sembly and an instrument manifold while also passing a pair of fluid pre3gure signal3 from a corresponding pair of NPT ports in the orifice plate as~embly through the in~trument manifold and thence to a pres3ure tran~ducer for detecting pre3sure differential acros~ the orifice plate asqembly and thereby measuring flow rate.

2. Background of the Invention In~trument manifolds are commonly employed in differential pres~ure ~y~tems between the ~ource of the differential pregsure and the pressure transducer, monitor or meter. In a typical installation, a three-valve or five-valve instrument manifold i~ installed between an orifice plate as~embly and a differential pres3ure tran~ducer to normally transmit a pair of pre3sure signals to the transducer, and to allow for intermittent testing of the measuring system while line fluid passes through the orifice plate assembly. The in~trument manifold may be connected to the orifice plate assembly by either remote couplings or direct (close) coupling~. While the remote coupling technique provide~ a high degree o~ flexibility with respect to plaoement of the in~trument manifold, direct or cloqe coupling of the orifice plate assembly and the instrument manifold is often preferred to reduce travel of the preqsure signals and thus increase sy3tem accuracy, to reduce fluid-tight interconnection~ and thereby increase pres3ure signal reliability, to ~implify rod-out operations, and to significantly reduce instrument manifold installation costs.
In~trument manifold in~tallation cost~ can most dramatically be reduced when the close coupling equipment independently provides the structural connection between the orifice plate assembly and the instrument manifold. While the savings from this installation technique are significant, the use of direct or close coupling between an orifice plate a3sembly and an instrument manifold ha~ long been limited, primarlly due to G3~Z

justified concern that over an extended period of time the close coupling interconnection may be unable to with~tand the industrial environment in which the~e components are placed. In many cases, thi~ concern is due to the periodic or continuou~
presence of high vibration of the fluid line in ~hich the orifice plate assembly is placed. The concern o~ the sy~tem operator i3 that vibration of the oririce plate assembly will be tran~mitted through the close coupling connectors to the in~trument manifold, resulting in leakage and/or gtructural failure of the close coupling connectorg. Thig problem ig no~ easily overcome, since any mechanism which either reduces this vibration or i9 adapted to withstand this vibration over a long period of time must be cost effective and easy to install, preferably does not increase the relatively short distance between the orifice plate assembly and the instrument manifold, and ideally is highly versatile so that it can be employed between various types of differential pressure assemblies and instrument manifolds.
Many types of coupling devices are not suitable for transmitting pre~sure signals from an orifice plate assembly to an instrument manifold. U.S. Patent No. 2,852,281, for example, discloses a fluid pressure coupling that uses a wedged sealing sleeve. Orifice plate assemblies are conventionally provided with tapered ~PT threads which form a fluid-tigkt me~al-to-metal seal between the orifice plate assembly body and the threaded coupling, and accordingly a coupling with straight threads and an O-ring 3eal is not practically usable with conventional orifice plate assemblie~. An end portion of each coupling ad~acent the instrument manifold must also be rotatable, so that apertures within that end portion can be rotatably aligned with corresponding apertures in the instrument manifold flange for structurally interconnecting each coupling with the instrument manifold. U.S. Patents 2,343,235, 2,919,147, and 3,151,893 each disclose couplings which are intended to enable one end of a coupling to be rotated at a selected angular position while maintainin8 a fluid-tight connection between the other end of the coupling and the body to which the coupling is connected. Each of these couplings, however, again discloses straight threads rather than tapered NPT threads of the type used in a ~gi3~2 conventional orifice plate a~sembly. Moreover, the coupling~ do not include a pair of apertures or other quitable mean3 for mechanically connecting the free end of the coupling with a flange of an instrument manifold. Finally and most importantly, these patents do not teach a practical solution to the problem which has reduced the commercial use of direct couplirgs between an orifice plate assembly and an inqtrument manifold, namely to provide a mechanism which can withstand the prev~ously described vibrational forces over a long period of time, and thereby overcome the leakage concern.
Coupling~ which structurally interconnect an orifice plate assembly with an instrument manifold thus mu~t 3ati~fy special problem~ inherent in this application, and generally are specially adapted for this particular u3e. Direct coupling of an orifice plate assembly with an instrument manifold is conventionally accomplished by a pair of nipples each having NPT
threads at each end, with a "football" mechani~m including a pair of through apertures provided at the instrument manifold end of each nipple for mechanically interconnecting the coupling to the in~trument manifold. U.S. Patent No. 4,672,728 discloses a pair of nipples for structurally interconnecting an instrument manifold with an orifice plate assembly and for passing the pair of signals from the orifice plate assembly through the instrument manifold and to a pressure transmitter. This patent al~o discloses a preferred instrument manifold having a removable flange connected to the manifold body with a pair of specially adapted fittings for forming a fluid-tight connection between each football and the corresponding fitting. Apertures in each of the footballs are aligned with corresponding apertures in the instrument manifold flange, so that the ~instrument manifold can be s~ructurally connected to the orifice plate a~sembly by the pair of nipples and footballs. Other types of direct or close couplings between an instrument manifold and an orifice plate assembly are shown in U.S. Patent 4,572,728, which also depicts the previously described NPT ports formed in a pair of circular flange bodies of an orifice plate assembly.
The direct coupling connectors disclosed in the latter two patents each ser~e the function of ~ealing an NPT port in an orifice plate assembly with a corresponding port in an instrument manifold, and al~o provide mean~ for independently structurally interconnecting the in~trument manifold with the orifice plate assembly. While these connectors have been widely uQed, they often do not satiafy the cugtomer~s reliability concern for high vibration application~. When placed in Quch an environment, the vibrating connectors, coupled with the weight of the instrument manlfold and often the weight o~ the pre~sure tranqducer, may cause the nipple9 to l009en, thereby resulting in leakage of pressure and thus poor signal reliability. The~e connectorq are also particularly ~u~ceptible to leakage, or even structural failure, when the instrument manifold (or transmitter connected thereto) is sub~ected to a vector rorce perpendicular to a plane passing through each of the axes of the connectors. Since the connectors are spaced apart, they are capable of with~tanding a reasonable vector force within this plane, but are not able to withstand a similar magnitude vector force perpendicular to this plane. Accordingly, customers faced with such a hi~h vibration environment, or faced with other environments which would cau~e one to que~tion wh~ther the nipples can continually withstand the forces which may act on the instrument manifold without allowing ~ignal pressure leakage, often utilize the much more expen~ive and less desirable installation technique of providing a separate "platform" for mounting the instrument manifold structurally separate from the ori~ice plate as~embly, and then interconnect the orifice plate assembly and the remote instrument manifold with flexible fluid lines.
The disadvantages of the prior art are overcome by the present invention, and improved method~ and apparatus are 3~ hereinafter provided for reliably forming a structural interconnection between a standard instrument manifold and an orifice plate as~embly using a pair of connector flange assemblie~ aq deqcribed herein.
3. Summary of the Invention A suitable environment for the apparatus according to the present invention include~ an orifice plate assembly or o~her differential pressure aasembly, an in~trument manifold, and a pressure transducer, gauge, monitor or meter. The orifice plate 2~6~2 aq~embly is 3uitable ror placing along a rlow line, and in~lude~
a pair of NPT ports in fluid communication with opposing ~ides of an orifice plate. The pre~sure differential across the orifice plate is tran3mitted through these ports and pa~3ed through the instrument manifold to the pressure tranqducer to measure the flow of line fluid through the orifice plate assembly. The external surface of the orif~ce plate as3embly adjacent the NPT
portq i9 typically curved, but could be planar. The In~trument manifold i9 provided with an orifice-side flange having a pair of pressure receiving ports and a plurality of apertures surrounding each of those ports for structurally interconnecting the instrument manifold with each of a pair of ~tabilized connector flange assemblies, which in turn are connected to the orifice plate assembly.
Each of the stabilized connector flange assemblies comprises a connector flange having an NPT threaded end for engagement with a corresponding port in a differential pressure assembly, and a fl'ange end having a pair of apertures for receiving bolts to interconnect each connector flange assembly to the instrument manifold. Each connector flange has a straight fluid passageway for transmitting pressure signals from the correQponding NPT port to She instrument manifold and thence to the pressure transducer. A guiding portion of each connector flange is axially spaced between the NPT threads and the flange 2S end, and preferably has a cylindrical outer configuration. An external threaded portion of each connector flange is axially spaced between the guide portion and the flange end. Each connector flange assembly further comprises a stabilizer foot having a cylindrical internal surface for sl~ding engagement with the external surface of the guide portion of the connector flange, and a pair of stabilizer members each spaced radially a Q~bstantial diQtance from the corresponding NPT threads for engaging the outer surface of the differential presqure assembly ad~acent the NPT port. Finally, each stabilized connector flange assembly includes a ten~ioning nut for threaded engagement with the threaded portion of the connector flange so aQ to exert a qubstantial axially directed force on the stabilizer foot, thereby forcing the stabilizer foot into rigid engagement with the orifice plate assembly~

~0~631Z

In it~ aa~embled po3ition, the stabilizer foot prevent~
movement in any radial direction of the connector flange with respect to the differential presgure a~gembly~ so that the instrument manifold once bolted to the pair of connector flange end~ i~ thus ~tructurally connected to the differential pressure a~sembly Moreover, the NPT threads of each of the connector flange~ are continually in tension cau~ed by the axially directed force of the ten~ioning nut, which further reduce~ the likelihood that either of the connector flanges will become loosened from the differential pressure a~embly. All forceq which might be exerted on the in~trument manifold may be pa~ed to the differential preggure a~gembly through the pair of stabilized connector flange a~semblies, and primarily through the pair of ~tabilizer feet. Accordingly, high radially-directed force~ are lS not placed on the NPT threads of either connector flange, thereby substantially increasing system reliability and reducing concern for pre3sure signal error.
According to the method of the present invention, a tensioning nut and a stabilizing foot are each placed about a corresponding connector flange, and each connector flange is threaded to a corresponding port in the orifice plate assembly so that the NPT threads of the connector flange form a fluid-tight metal-to-metal ~eal. The flange end of each connector flange i~
thereafter rotated ~o that it~ aperture~ may be aligned with the corresponding aperture~ in the orifice flange end of the inqtrument manifold, and ~ealed engagement of the NPT thread~ i9 maintained while each connector flange i~ so rotated. In addition to being rotated for proper alignment with the instrument manifold, the connected flanges may need to be rotated ~o that the Plange en~ qurfaces of the two connector flange~ are positioned at approximately the same axial location, so that the single flange of the instrument manifold can be sealingly mated to the two ~tructuralIy independent flange end~ of the connector flange~. Once the flange end~ ha~e been properly rotated, each of the tensioning nuts ig rotated on the threaded portion of a correqponding connector flange to force each of the stabil~zer feet into fixed engagement with the outer surface of the orifice plate assembly adjacent the corresponding NPT port. Finally, conventional bolt~ may be uqed to structurally interoonneot the flan~e end of eaoh of the connector flanges with the instrument manifold flange, thereby also energizing a fluid-tight seal between the instrument manifold and each of the stabilized connector flange assemblies.
It i~ an object of the pre3ent invention to provide improved methods and apparatus for reliably interconnecting an instrument manifold with a differential pres~ure assembly, ~uch that the in~trument manifold i~ gtructurally interconnected thereto by a pair of stabilized connector flange assemblieq which qubstantially reduce or eliminate the likelihood of fluid pre~sure lo~s between the differential pressure assembly and the instrument manifold~ -It i~ a further object of the present invention to structurally interconnect an instrument manifold with adifferential pressure assembly utilizing a pair of stabilized connector flange assemblies which do not significantly increaqe the cost or complexity of forming a fluid-tight connection between the instrument manifold and the differential pressure assembly, and which substantially reduce the likelihood that vibration will cause leakage of fluid pressure over a prolonged period of time~
It is a further ob~ect of the present invention to interconnect a differential pressure assembly and an instrument manifold using a pair of stabilized connector flange assemblies each including a connector flange, a stabilizer foot, and a tensioning nut. According to the method of the present invention~ the tensioning nut and ~tabilizer foot are slid over the NPT threaded end of each connector flange, and eaoh connector flange is thereafter rotated so that its threaded end form~ a metal-to-metal seal with the corresponding NPT port in the differential pressure assembly. While thi~ metal-to-metal seal is maintained, each connector flange is rotated ~o that (1) apertureq within each flange end will be aligned with corresponding apertureq in the instrument manifold, and (2) the flange end surfaces of the two connector flanges are at approximately the same axial location, i.e., so that their planar end surfaces lie within or are very close to being within a g 3in~1e plane perpendicular to the connector flange axe~, thereby enabling the single planar orifice plate facing end surface of the inqtrument manifold to gubsequently become secured and sealed to the pair of connector flange end surfaces. The tensioning nut lq therearter rotated so ~hat each stabilizer foot is brought into secured engagement with the differential pres~ure a~sembly, thereby gubgtantially reducing or eliminating radially directed forces between the NPT thread~ of the connector flange and the corresponding threads of the differential pre~sure as~embly.
Conventional bolts may thereafter be passed through the apertures in each connector flange and the correqponding apertures in the inqtrument manifold, such that the instrument manifold may be supported from the differential pre~ure assembly solely by the pair of stabilized connector flange aqsemblieq.
It is a feature of the preqent invention that the qame stabilized connector flange assemblies may be used to reliably interconnect a conventional instrument manifold with various types of differential presqure assemblies, including orifice plate aqsemblies having either ~ rval ~ r or planar surfaces adjacent its NPT port~. ' It is a further feature of the present invention that the stabilized connector flange as~emblies may be used to interconnect various type~ of instrument manifolds with a differential preqsure a~embly, including inqtru~ent manifold~
~5 having flange~ integral with the manifold body and in~trument manifoldq having removable flanees.
It is another feature of the present invention that the pair of connector flange aqsemblies of the present invention which structurally interconnect an inqtrument manifold with a differential pres~ure assembly do not significantly increaqe the flow path length between the differential pres~ure assembly and the instrument manifold, thereby maintaining high system reliability.
A significant advantage of the stabilized connector flange assemblies according to the pre~ent invention is that an instrument manifold may be reliably mounted to and be solely supported by a differential pressure as~embly utilizing a pair of stabilized connector flange aqsemblies, wherein vibration of the 3~

differential preasure as~embly will not cause the connector flange assemblie3 to become loosened from the dlfferential pre~sure agsembly, 90 that ~y~tem leakage is 3ub~tantlally reduced or eliminated. Accordingly, significant installation cost savings can be realized by utilizing the stabilized aonnector flange assemblleg of the present invention, and avoiding the expense of providing a ~upport or platform ~tructurally independent of the orifice plate assembly for supporting the ingtrument manifold and/or pres~ure transducer.
These and further objects, feature~ and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.
Brief Description of the Drawings Figure 1 is a simplified pictorial view illustrating one of a pair of stabilized connector flange a~semblies of the present invention structurally interconnecting an instrument manifold with an orifice plate assembly.
Figure 2 is a cro~s-sectional view of a stabilized connector flange assemblies taken along line 2-2 in Figure 1.
Figure 3 is a more detailed cross-sectional view of one of the stabilized connector flange assembly shown in Figure 1 without an instrument manifold connected thereto.
Figure 4 is a cross-sectional view of another embodiment of a stabilized connector flange assembly connected to another type of differential pressure assembly.
Figure 5 is a pictorial view of still another embodiment of a stabilized connector flange aligned for bo~ted connection with an instrument manifold.
Figure 6 is a cross-sectional view taken along line 6-6 in Figure 5.
Detailed De~cription of Preferred Embodiments Figure 1 depicts a five-valve in~trument manifold 10 mounted to an orifioe plate assembly 12 by a pair of stabilized connector flange assemblies 14 according to the present invention. A pressure transducer 16 and its accompanying electronics head 18 are mounted to the opposing side of the instrument manifold 10, with the transducer 16 serving to measure ~0~

the flow rate of fluid through the flow line 20 and through the orlfice plate 22 therein~ The orifice re~triction create3 a pres~ure differential acro~ the orifice plate 22, and fir~t and second pre~ure signal3 are tran9mitted through the corresponding tapered NPT ports 24 (see Figure 3) in the orifice plate as~embly 12, through the regpective inlet port~ 26 and outlet ports 27 in the instrument manifold 10, and to the preg~ure tranaducer.
During normal use, the valve 32 and lt~ corre~ponding valve on the blind ~ide of manifold 10 are thus opened for transmitting re~pective first and ~econd pre~ure ~ignal~ to the pres~ure tran~ducer. The~e valve~ may, however, be closed and valve 30 and its corre~ponding valve opened for intermittently testing the ~ystem while line fluid continues to pass through the orifice plate a sembly 12. Finally, a bleed valve 28 i~ provided for venting pregsure during the testing operation. This testing procedure i~ well known in the art and thu~ is not described herein.
The in~trument manifold lO is shown with flange 34 integral with the manifold body on its orifice plate side. The flange 34 has a plurality of through apertures 36 each radially outward of one of the respective inport ports 26. Bolt~ may thus be threaded through thege apertures for securing an instrument manifold to a football member, as shown in U.S. Patent 4,582,089. The orifice plate as~embly 12 include~ a pair of disk-shaped bodie~ 38 secured together by bolt~ 40, with each of the bodies 38 having an external curvalinear surface 42 adjoining a respective NPT threaded outlet port. Although only one stabilized connector flange a~sembly 14 i~ ~hown in Fig. 1, it should be under~tood that a second substantially identical flange a~sembly is behind the depicted assembly 14, ~o that both ~ir~t and second flange assemblies are used to independently mount the instrument manifold 10 to the orifice plate asqembly 12. Each of the flange agsemblies 14 include~ a connector flange 50 having a flange end 58, a stabilizer foot 52, and a ten~ioning nut 54.
Each assembly 14 may thu~ replace a re~pective nipple and football as de~cribed in U.S. Patent 4,582,089, although the flange assemblie~ a~ herein de~cribed are ~ignificantly better able to withstand vibrational force~ acting on the instrument i312 manifold, thereby en~uring high ~ignal pre3sure rellability from the orifice plate a~embly 12 to the tran~ducer 16 over a long period of time. Moreover, the flange aqqemblie~ of the preqent invention are able to tran3mit forces to the flange a3Qembly 5 which are applied to the in~trument manifold or pre3~ure transducer, particularly vector force~ perpendicular to a plane pas~ing through the axis of the flange a~semblie~. Accordingly, an intermittent force applied to the pre~ure tranQducer a~ ~hown in Figure 1 can be much more ~afely tran~mitted to the orifice plate a~embly 12 by the connector flange asQemblie~ of the pre~ent invention than wa~ po~sible with prior art connector flange~. As a re~ult, inQtallation coQt~ are reduced (no ~pecial platform required), yet reliable signal~ are tran~mitted, and maintenance coqt~ are minimized.
Figure 2 depict3 in cross-section the pair of flange ends of the stabilized connector flange assemblies 14 according to the pre~ent invention, and the relation~hip of the~e flange endq 58 to the flange 34 of the manifold 10. Figure 2 thus depict~ the aylindrical-shaped upper and lower flow pa~ageways 92, 94 through the respective upper and lower flange assemblies, with each flow pa~sageway placing a respective port in the orifice plate assembly 12 in fluid communicatin with a respective inlet port 26 of the instrument manifold. Each flange end 58 ha~
a pair of through apertures 96 on radially oppoqing sides of each of the reqpective pas~ageways 92, 94. Each aperture 96 may have a generally elliptical cro~s-~ectional configuration to better accomodate minor mi~alignment between respective aperture~ in the connector flange and the instrument flange Accordingly, the ~emima~or axis of each aperture is generally parallel to a plane paq~ing through the axes of the passageway~ 92, 94. A bolt 98 is received within each aperture, and i~ threaded to the flange 34 of the in~trument manifold to ~tructurally interconnect the instrument manifold and the connector flange.
Figure 3 depicts in greater detail one of the ~tabilized connector flanges according to the pre~ent invention. The qtabilizer foot 52 and the ten~ioning nut 54 are each mounted on the connector flange 50. The connector flange 50 include~ a tapered thread NPT end 56 fixed thereon for metal-to-~0~312 metal sealing engagement with a corre~ponding port 24 in the orifice plate assembly, and an opposing flange end 58 fixed thereon and including flange component 60 having first and second through apertures 96 a~ described above. The connector flange 50 ha~ a central axi~ 64, and a cylindrically-shaped through passageway 92 formed about the central axis 64 for transmitting a pres~ure signal from the NPT outlet port in the orifice plate assembly to a corre~ponding inlet port of the inQtrument manifold. Each of the apertures 96 has an axis 68 parallel with the central axis of its re~pective connector flange.
Each connector flange 58 also includes a guide portion 70 fixed thereon axially between the threaded end and the flange end. The guide portion 70 has an external cylindrically-shaped guide surface 72 of a uniform outer diameter. A threaded portion 74 is axially fixed on the connector flange between the guide portion and the flange end, and has straight-wall external threads 76. The length of the through pas~ageway 92 in each connector flange 50 is relatively short, and preferably less than about 1.3 times the maximum height (in the radial direction) of the flange component 60. In a typlcal installation, the maximum height of component 60 is approximately 2.50 inches, and the centerline spacings between the apertures 96 is 1.625 inches to correspond with the centerline spacings in the apertures of the instrument manifold for receiving the bolts 98.
The tensioning nut 54 has internal threads 80 for threaded engagement with the external threads on the connector flange 50, and has straight-wall exterior surfaces 82 to facilitate torqued rotation of the nut 54 with a conventional wrench. The nut 54 includes a substantially planar end surface 84 for engagement with the stabilizer foot 52.
The stabilizer foot 52 preferably has a generally parallelepiped body portion 86 with a pair of stabilizer members 88 affixed thereto and projecting axially toward the orifice plate assembly. The internal cylindrically-shaped surface 89 in the body portion 86 has a diameter only slightly greater than the external cylindrical guide surface 72 on the connector flange, so that the foot 52 can move axially but is radially fixed with respect to the connector ~lange. As shown in Fig. 3, the 1G3~2 stabili~er member~ 88 each have a rectangular cro~3-~ectional configuration extending along the length of each foot. Each of the stabilizer member3 88 are ~ub~tantially radially outward of the NPT thread~ on the connector flange, and ePficiently provide outrigeers for rigid engagement with an external surface of the orifice plate as~embly 12. The ~tabilizer member~ may be spaced radially a di~tance of at lea~t 1.5 time3 the nominal diameter of the tapered NPT thread~ on the connector flange, and preferably at least 1.5 times the unirorm diameter of the external guide surface 72 on the connector flange, so that the stabilizer members serve as outrigger3 and perform a qignificant mechanical advantage of efficiently tranqmitting radially-directed force~
between the orifice plate assembly and the connector flange.
Each 3tabilizer member 88 thus has a pair of contact points thereon for engagement with a corresponding body surface of the orifice plate assembly. Those contact points lie along and thu3 define a linear contact line 90 for ~tabilized engagement with the curvalinear exterior surface 42 of the orifice plate assembly 12 shown in Fig. 2. If the exterior surface of the orifice plate assembly is planar, the configuration of the stabilizer members allows the~ to engage and al~o be rigidly secured thereto. Thus the stabilizer foot 52 may be used for engaging an orifice plate a~sembly with either a curvalinear exterior ~urface, as shown in Figure 3, or a substantially planar exterior ~urface, as shown in Figure 4. The length of the stabilizer foot (in the direction of the elongate ~tabilizer member~ not critical, but eenerally approximates the nominal diameter of the tensioning nut. Fig. 3 also depict~
an elastomeric seal ring 62 radially spaced between the through passageway 92 in the connector flange and the bolt~ 98, ~o that the elastomeric 3eal 62 engage~ a planar end surface of the in~trument manifold and seals therebetween when the bolt~ 98 secure the in~trument manifold to the connector flange.
Accordingly, the instrument-facing face of the connector flange is provided with a circular groove 66 for receiving the elastomeric ~eal 62.
The connector flange 50' shown in Fig. 4 is ~imilar to the previou~ly de~cribed flange 50, but has a threaded aperture 97 for receiving the threaded ends of conventional bolts 98 paqsing through corresponding apertures in the instrument manifold. The instrument-~ide face surface 91 of the flange 50' iq planar, and is sealed to the instrument manifold by an ela~tomeric seal carried on the inqtrument manifold. The alternate flange aqsembly 14' shown in Fig. 4 may be slightly shorter than the aqqembly 14 described above, since axial space need not be provided for bolt heads between the tensioning nut 54 and the flange component 6O'. Figure 4 thus depicts the planar end surfaces 93 of foot 52 in fixed engagement with the planar surface 43 of the dif~erential pressure assembly 12~ adjacent the NPT port 24.
The connector flange assembly of the present invention is thus significantly better able to withstand a vector force as shown in Figure 4 and reliably transmit that force to the orifice plate assembly than prior art connector flange~. The force would typically be applied to the instrument manifold or pressure transducer, although the benefit of the invention can be understood by considering the force applied to the flange end of the connector flange, as depicted. The threaded end 56 of the connector flange is structurally weak, but the applied force is transmitted to the orifice plate assembly 12' by the foot 52 and its stabilizer members which are spaced radially outward of the threadq 57. Accordingly, this inherently weak threaded end 56 i9 avoided, and portion 96 Or the connector flange (which may be the new weak point) can easily have a wall thickness substantially greater, preferably at least 25% greater, than the threaded end 56. Since portion 96 is both structurally stronger and physically closer to the applied force than the threaded end 56, it is significantly less likely to fail than the threaded endc of prior art connectors in reqponse to the application of the force.
The method for structurally interconnecting an instrument manifold with an orifice plate asqembly will now be described. As previously indicated, first and second connector flanges, first and second stabilizer feet and first and second tenqioning nuts are provided as described above. A respective tensioning nut is then placed over the threaded end of a corresponding connector flange and is threaded to the external t;3~2 threads thereon. In order to provide sufficient room for subsequently obtaining a reliable metal~to-meta~ seal between a connector flange and the orifice plate assembly, the tensioning nut i~ preferably fully threaded on a respective oonnector flange so that it i~ cloqely ad~acent the flange end thereof.
Thereafter, a corresponding ~tabilizer foot is placed over the threaded end of a reqpective connector flange, and it~ internal cylindrical ~urface slid over the external cylindrical ~urface on the connector flange. Each of ~he firqt and second connector flange~ may then be rotated 90 that it~ NPT thread~ obtain the deqired metal-to-metal ~eal with the corresponding threaded NPT
port in the orifice plate as~embly. In particular, it qhould be noted that no other ~ealing member need be used to e~tablish a reliable seal between the orifice plate asqembly and the connector flange. The construction of NPT threads is such that the de~ired metal-to-metal seal may be maintained over at least approximately one turn of the NPT threads. Accordingly, while this metal-to-metal is maintained, each of the connector flange~
are rotated ~o that its apertures 96 will be aligned with the corresponding apertures in the instrument manifold. For instance, assuming that the corresponding apertures in the instrument manifold are horizontally spaced from but vertically at the qame elevation of a corresponding inlet port in the instrument manirold, the apertureq 96 in each of the connector flanges will be aligned so that the apertures 96 in each of the flange aqsemblies are similarly at the same vertical elevation, with each aperture 96 being horizontally spaced from pasqageway 92.
In order to obtain a reliable seal between the single face Or the inqtrument manifold and both of the structurally independent end surface~ of the pair of connector flange~, it may be neces~ary to further tighten one of the connector flanges with reqpect to the orifice plate a~sembly, so that the end surfaces of the fir~t and second connector flanges are at approximately the same axial position. In other words, the end surfaces of the first and second connector flanges should be spaced axially no more than approximately 0.020 inches apart to enqure that each of the connector flange~ will be able to form a reliable seal with ~ i3 ~ ~

the instrument mani~old. Thi~ final alignment of the connector flanges to ensure that their in~trument facing end surface~ are approximately within a single plane, i.e., flat ~ith respect to each other, will be accompli3hed with successive one-half turns of one or both of the connector flanges, since radially opposing apertures 96 in each of the connector flange ends must also be aligned with the corresponding aperture~ in the instrument manifold. The spacing between the individual thread~ 80 on each connector flange thus provides ~ufficient axial movement of each connector flange regulting rrom a one-half turn to maintain the desired flatness of the pair of end surfaces (within approximately 0.020 inches).
Once the connector flanges have been properly rotated so that each Or their apertures 96 are aligned with the corresponding apertures in the in~trument manifold and the flange ends are axially aligned or ~'flat" with respect to each other as described above, each of the tensioning nuts may be threaded so that its end surface 84 engages the corresponding end surface on the stabilizer foot, and forces the stabilizer members into engagement with the corresponding exterior surface of the orifice plate assembly. A rotational torque Or at least 200 foot pounds may be applied to each tensioning nut, which will exert a substantially axially-directed force on each of the stabilizer feet to force each foot into rigid engagement with the orifice plate as~embly. This compressive force on each of the feet will also place the NPT threads of each connector flange in tension, which further reduces the likelihood of a connector flange inadvertently becoming loose from the orifice plate assembly under high vibrational forces which might otherwise cause leakage Or a pressure signal to the transducer.
After each of the connector flanges has been rigidly secured to the orifice plate assembly as described above, conventional bolts 98 may be used for interconnecting the flange end of each of the connector flanges with the in~trument manifold, since the apertures in the flange end Or each connector flange will already be aligned with the corresponding apertures in the instrument manifold. Once the instrument manifold 10 has been rigidly gecured to the orifice plate assembly 12 by the ~O~

firat and second aonnector flange assemblies as described herein, another instrument manifold and one or more pressure tran3ducers 9 sensors or measurement instrumentg may be corneoted to the instrument manifold 10, so that the connector flange~ of the pre~ent invention may independently atructurally ~upport not only an ins~rument manifold from the orifice plate assembly, but one or more instrument manifolds an~/or pres~ure transducers.
Figure 5 is a pictorial view of another embodiment of the present invention, illustrating a pair of identical connector flanges 114 for ~olely interconnecting and supporting the instrument manifold 10 from an orifice plate assembly 12'.
Fieure 5 illustrates the conventional spacing of the connector flanges threaded to the NPT ports in the orifice plate assembly, and illustrate~ the spaced flange ends 118 generally similar to the flange endQ 58 ~hown in Figure 2. Each of the connector flange as~emblies includes a connector flange 116 with a tapered NPT threaded end 115 (aee Figure 6), a flange end 118 and a threaded portion 120 a3 previougly discussed. A guide portion is not included on each of the connector flanges, since the stabilizer members and tensioning nut are provided as a unitary component. A pair of bolts 122 are provided in each flange end 118 for connecting the instrument manifold 10 thereto. The spacing between the bolts in each connector flange 118 is thus substantially identical to the spacing between the corresponding radially opposing apertures 124 in the instrument manifold.
Figure 6 depicts the through pa~sageway from the orifice plate assembly 12' to the instrument manifold 10. The NPT threads thus form a metal-to-metal seal between each connector flange assembly and the orifice plate as~embly, and the 0-rin~ 128 forms a ~eal between the flange end~ 118 and 126.
A stabilizer foot structurally separate from the nut is not prGvided for the embodiment shown in Figure~ 5 and 6, but rather the stabilizer nut 130 is provided with a circular or ring-~haped stabilizer portion 132 structurally a~fixed thereto. Accordingly, the threads 136 on portion 120 serve as both a mating thread for the nut, and a guide surface to keep the ~tabilizer portion 132 substantially aligned with the axi~ 138.
Torqued rotation of the nut 130 thus forces the stabilizer 31X~

_19_ portion 132 into gtabilized engagement with the body surface 140 of the orifice plate a~sembly. Portion 132 may be easily fabricated by boring a cylindrical cavity 142 in the orifice plate assembly facing end of the nut. It should be under~tood that this cavity may al~o be conical-shaped quch that the portion 132 has a circular edge ~urface rather than a circular flat surface for engaging the orifice plate assembly.
Since the final torqued rotational position of the nut 130 for achie~ing rigid and stabilized engagement of the portion 132 with the orifice plate asgembly is not controllable, a pair of parallel spaced elongate stabilizer members on a stabilizer foot are not practical. Rather, a single ring-shaped stabilizer member may be provided which is formed as a unitary portion of the nut. Alternatively, a plurality of stabilizer members may be positioned circumferentially about the nut with slot~ or gaps therebetween. If the body surface 140 of the orifice plate assembly, as shown in Figures 5 and 6, is a planar surface, the circular planar end surface of the stabilizer portion 132 is in stabilized engagement with the surface 144.
Providing a ~tabilizer member within a planar surface for engagement with the orifice plate assembly has a disadvantage in that the correqponding eneaging surface of the orifice plate assembly may not be flat, i.e., that surface may be nicked, have burrs thereon, or may not be planar with respect to the central axis of the connector flange. Accordingly, the spaced parallel stabilizer members as shown in Figure 4 may have an angled exterior surface 95 which defines a sharp edge surface for engaging the exterior planar surface of the orifice plate assembly. Similarly, the exterior surface of the stabilizer member 132 formed as part of the nut 130 in Figure 6 may have the tapered exterior to define a sub~tantially circular knife edge ~urface for line contact engagement with the orifice plate assembly.

The components of the stabilized connector flange as3emblies according to the present invention are preferably fabricated from stainle~ 3teel. The elastomeric ~eal between the stabilizer flange and the instrument manifold may be formed from any suitable elastomeric materials, including natural or synthetic rubber, Delrin~, or Teflon~.
Although the present invention is particularly well-suited for structurally interconnecting an in~trument manifold with an orifice plate assembly, it should be understood that the connector flange as3emblies as described herein may also be used to interconnect any differential pressure apparatuq having a pair Or NPT threaded outlet ports with an instrument manifold. Also, the connector flange assemblies of the present invention may be used with various type~ of instrument manifolds, including three-valve and five-valve instrument manifolds, instrument manifolds with flanges integral to the flange bodies and instrument manifolds with removable flanges. Also, the present invention may be used with various types of differential pressure sensing equipment or transmitters, including differential pressure gauges, meters or recorders.
Other alternative forms of the present invention will suggest themselves from a consideration of the apparatus and techniques described herein. Accordingly, it should be understood that the apparatus and methods described here~n and shown in the accompanying drawings are intended as exemplary embodiments of the present invention, and not as limitations thereto.
What is claimed is:

Claims

1. Apparatus for structurally interconnecting an instrument manifold with a differential pressure assembly, the instrument manifold having first and second pressure receiving inlet ports, first and second pressure transmitting outlet ports, and a plurality of apertures positioned radially outward of a corresponding inlet port for receiving securing members to structurally interconnect the instrument manifold to the apparatus, the differential pressure assembly including first and second body surfaces and having first and second tapered NPT
threaded outlet ports adjoining a respective body surface each for transmitting a pressure signal through the instrument manifold and to a differential pressure sensor, the apparatus comprising;
first and second connector flange means each having a central axis and a through passageway formed about the central axis for transmitting a pressure signal from a corresponding NPT
outlet port in the differential pressure assembly to a corresponding inlet port in the instrument manifold, each connector flange means including:
(a) a tapered NPT threaded end fixed on the connector flange means for metal-to-metal sealing engagement with the corresponding tapered NPT
threaded outlet port in the differential pressure assembly, (b) a flange end fixed on the connector flange means and including first and second apertures each positioned radially outward of the through passageway, (c) a guide portion fixed on the connector flange means axially between the threaded end and the flange end, the guide portion having an external guide surface, and (d) a threaded portion fixed on the connector flange means axially between the guide portion and the flange end and having external threads;

first and second stabilizer feet means each mounted on and axially movable along a corresponding connector flange means and having an internal surface for sliding engagement with the external surface on the guide portion, each stabilizer foot means including a plurality of stabilizer members each spaced substantially radially outward of and projecting axially toward the threaded end of the respective connector flange means for rigid engagement with the corresponding body surface on the differential pressure assembly; and first and second tensioning nut means each threaded to the threaded portion of the respective connector flange means for exerting a substantially axially-directed compressive force on the corresponding stabilizer foot means to force the foot means into stabilized engagement with the corresponding body surface on the differential pressure assembly, such that each of the NPT
threaded ends of each connector flange means will be in tension from the compressive force of the tensioning nut means, and the stabilizer feet means will transmit substantially all radially-directed forces acting on the connector flange means to the differential pressure assembly.

2. The apparatus as defined in Claim 1, wherein:
the external guide surface of the guide portion of each of the connector flange means is a cylindrically-shaped guide surface having a uniform diameter; and the internal surface of each of the first and second stabilizer feet means is a cylindrically-shaped internal surface for sliding engagement with the external guide surface, the internal surface having an internal diameter slightly greater than the uniform diameter of the guide surface.

3. The apparatus as defined in Claim 2, wherein each of the stabilizer members includes a plurality of contact points for stabilized engagement with the corresponding body surface on the differential pressure assembly, the stabilizer members being spaced radially apart from each other a distance of at least 1.5 times the uniform diameter of the external guide surface of the corresponding connector flange means.

4. The apparatus as defined in Claim 3, wherein each of the plurality of contact points for each of the stabilizer members define a linear contact line for stabilized engagement with the corresponding body surface on the differential pressure assembly.

5. The apparatus as defined in Claim 1, wherein the through passageway in each of the connector flange means has a length less than about 1.3 times a maximum width of the flange end of each of the connector flange means.

6. The apparatus as defined in Claim 1, wherein each of the feet means has a generally parallelepiped configuration.

7. The apparatus as defined in Claim 1, wherein the flange end of each of the connector flange means carries an elastomeric seal for sealing engagement between the flange end and the instrument manifold.

8. Apparatus for structurally interconnecting an instrument manifold with a orifice plate assembly, the instrument manifold having first and second pressure receiving inlet ports, first and second pressure transmitting outlet ports, and a plurality of apertures positioned radially outward of a corresponding inlet port for receiving securing members to structurally interconnect the instrument manifold to the apparatus, the orifice plate assembly having first and second body surfaces, and having first and second tapered threaded outlet ports adjoining a respective body surface each for transmitting a pressure signal to the instrument manifold, the apparatus comprising:
first and second connector flanges each having a central axis and a through passageway for transmitting a pressure signal from a corresponding outlet port in the orifice plate assembly to a corresponding inlet port in the instrument manifold, each connector flange including:
(a) a threaded end fixed on the connector flange for metal-to-metal sealing engagement with a corresponding tapered threaded outlet port in the orifice plate assembly, (b) a flange end fixed on the connector flange and including at least one aperture positioned radially outward of the through passageway, and (c) a threaded portion fixed on the connector flange axially between the threaded end and the flange end and having external threads;
first and second stabilizer members each spaced substantially radially outward of the threaded end of the respective connector flange and positioned axially between the flange end of a corresponding connector flange and the orifice plate assembly for rigid engagement with the corresponding body surface on the orifice plate assembly; and first and second tensioning nuts each threaded to a threaded portion of the respective connector flange for exerting a substantially axially-directed compressive force on the corresponding stabilizer member to force each stabilizer member into stabilized engagement with the corresponding body surface on the orifice plate assembly, such that each of the threaded ends of each connector flange will be in tension from the compressive force of the tensioning nut and the stabilizer members will transmit substantially all radially-directed forces acting on the connector flanges to the orifice plate assembly.

9. The apparatus as defined in Claim 8, wherein each of the first and second stabilizer members is rigidly fixed to a respective tensioning nut.

10. The apparatus as defined in Claim 8, wherein each of the stabilizer members includes a substantially circular contact surface for stabilized engagement with the corresponding body surface of the orifice plate assembly, the stabilizer member contact surface encircling the threaded portion of a respective connector flange and having a diameter of at least 1.5 times the nominal diameter of the threaded portion of the corresponding connector flange.

11. The apparatus as defined in Claim 9, wherein each of the stabilizer members and a respective tensioning nut are fabricated as a unitary member by forming a cavity in its orifice plate assembly facing end surface to define the stabilizer member.

12. The apparatus as defined in Claim 8, wherein:
the flange end of each of the connector flanges includes a pair of apertures each positioned radially outward of and substantially on radially opposing sides of the corresponding through passageway; and the pair of apertures in the flange end of each of the connector flanges has an aperture axis parallel to the central axis of the corresponding connector flange.

13. A method of structurally interconnecting an instrument manifold with an orifice plate assembly, the instrument manifold having first and second pressure receiving inlet ports, first and second pressure transmitting outlet ports, and plurality of apertures positioned radially outward of a corresponding inlet ports for receiving securing members, the orifice plate assembly including first and second body surfaces and first second tapered threaded outlet ports each adjoining a respective body surface for transmitting a pressure signal to the instrument manifold, the method comprising:
providing first and second connector flanges each having a central axis and a through passageway, each connector flange formed to include an threaded end fixed thereon, a flange end fixed thereon and including at least first and second apertures each spaced radially outward of the through passageway, and a threaded portion fixed thereon axially between the guide portion and the flange end;
providing first and second stabilizer members each spaced substantially radially outward of the threaded end of the respective connector flange;
providing first and second tensioning nuts;
positioning each tensioning nut over the threaded end of a corresponding connector flange such that each tensioning nut is supported on a respective connector flange;
positioning each stabilizer member over the threaded end of a respective connector flange such that each of the stabilizer members is spaced axially between the tensioning nut and the orifice plate assembly;
thereafter rotating each of the connector flanges for obtaining metal-to-metal sealing engagement between the threaded end of each of the connector flanges and the respective threaded outlet port in the orifice plate assembly;
while maintaining the metal-to-metal sealing engagement, rotating each of the connector flanges such that each of the plurality of apertures in the flange end are at a preselected rotational position;

thereafter rotating each of the tensioning nuts with respect to the threaded portion of each of the connector flanges such that each of the tensioning nuts exerts a substantially axially directed force on the corresponding stabilizer member to force the stabilizer member into stabilized engagement with the corresponding body surface on the orifice plate assembly; and fixedly interconnecting the flange end of each of the connector flanges with the instrument manifold while each of the apertures in the flange end is aligned with the corresponding apertures in the instrument manifold.

14. The method as defined in Claim 13, further comprising:
threadably torquing at least one of the first and second connector flanges to the orifice plate assembly such that an axial spacing between instrument facing ends of the first and second connector flanges is minimized.

15. The method as defined in Claim 14, wherein at least one of the connector flanges is threadably torqued to the orifice plate assembly such that the axial spacing between the instrument facing ends of the first and second connector flanges is less than about 0.020 inches.

16. The method as defined in Claim 15, wherein the step of rotating each of the tensioning nuts includes applying a force of at least 200 foot pounds to each of the tensioning nuts for exerting a high axially directed compressive force on each of the stabilizer members.

17. The method as defined in Claim 13, wherein the instrument manifold is structurally connected to the orifice plate assembly solely by the securing members, the first and second connector flanges, the first and second stabilizer members, and the first and second tensioning nuts.

18. The method as defined in Claim 13, further comprising:
structurally interconnecting a differential pressure sensor to the instrument manifold, such that the orifice plate assembly supports both the instrument manifold and the differential pressure sensor.

19. The method as defined in Claim 13, further comprising:
forming a cylindrically-shaped exterior guide surface having a uniform outer diameter on each of the connector flanges;
and forming a cylindrically-shaped interior surface on each of the stabilizer members having a diameter only slightly greater than the uniform diameter of the guide surface, such that each stabilizer member is axially movable with respect to its connector flange by the corresponding tensioning nut.

20. The method as defined in Claim 13, further comprising:
forming each of the stabilizer members and the respective tensioning nut as a unitary member having a cavity in its orifice plate assembly facing end surface radially inward of the stabilizer member, the cavity having a diameter of at least 1.5 times the nominal diameter of the threaded portion of a respective connector flange.