A METHOD FOR REDUCING STRESS IN A CONDUIT BRACE ASSEMBLY

FIELD OF THE INVENTION The present invention relates to a method using localized heating to relieve stress in a conduit brace assembly.

BACKGROUND OF THE INVENTION

Vibrating flow devices, such as, for example, densitometers and Coriolis flow meters are used for measuring a characteristic of flowing substances, such as, for example, density, mass flow rate, volume flow rate, totalized mass flow, temperature, and other information. Vibrating flow devices include one or more conduits, which may have a variety of shapes, such as, for example, straight, U-shaped, or irregular configurations. The one or more conduits have a set of natural vibration modes, including, for example, simple bending, torsional, radial, and coupled modes. The one or more conduits are vibrated by at least one drive at a resonance frequency in one of these modes for purposes of determining a characteristic of the flowing substance.

Vibrating flow devices include one or more electronics that transmit a sinusoidal drive signal to a drive, which is typically a magnet/coil combination with the magnet typically being affixed to the conduit and the coil being affixed to a supporting structure or to another conduit. The drive signal causes the drive to vibrate the one or more conduits at a resonance frequency in one of the natural modes. For example, the drive signal may be a periodic electrical current transmitted to the coil.

Vibrating flow devices include at least one pick-off that detects the motion of a conduit and generates a sinusoidal pick-off signal representative of the motion. The pick-off signal is transmitted to the one or more electronics, which, according to well known principals, determines a characteristic of the flowing substance or adjusts the drive signal, if necessary.

Vibrating flow devices may have one or more brace bars. It may be desirous to use a brace bar so that the vibrational mode employed for purposes of determining a characteristic of the flowing substance does not occur simultaneously with other modes of vibration. Accordingly, by varying the number and position of brace bars, the frequency at which the various modes of vibration will be induced can be somewhat

controlled. Furthermore, it may also be desirous to use a brace bar in order to reduce the stress, as the one or more conduits oscillate, on the connecting area between a manifold or flange and the one or more conduits.

Brace bars are typically connected to the conduits via a connection joint generated through a welding, brazing, or soldering operation. Connection of the brace bars to the conduits may stress or weaken the conduits in areas around where the connection joint is located. Since the area of the connection joint is subject to stress due to cyclical loading imparted by the oscillations, any stressing or weakening around this area may lead to catastrophic failure of the conduits. In previous designs, the stressing and weakening has been relieved through use of an oven. This process requires placing the entire conduit(s) and brace assembly in an oven and heating this assembly to a predetermined temperature, such as, for example 1162°C for a set amount of time, such as, for example, 37 minutes. While satisfactory for relieving the stressing or weakening of the conduits, this method has a number of draw backs. For example, since this process requires that the conduits and brace assembly fit within the oven, the process has generally been limited to use with smaller conduits. Furthermore, since the heating operation may damage the pick-off(s), drive(s) and other components, the current method requires that the conduits and brace assembly be connected, removed from the production line, taken to the oven, and then returned to the production line for assembly of additional components.

The present invention is directed to overcoming these disadvantages inherent in prior art conduit brace assemblies for vibrating conduits in flow devices.

SUMMARY OF THE INVENTION The scope of the present invention is defined solely by the appended claims, and is not affected to any degree by the statements within this summary.

According to one embodiment of the present invention, a method for reducing stress in a conduit brace assembly comprises the steps of forming a connection joint that connects a brace bar to a conduit and applying localized heat at the connection joint to relieve stress.

ASPECTS

According to one aspect of the present invention, a method for reducing stress in a conduit brace assembly comprises the steps of: forming a connection joint that connects a brace bar to a conduit; and applying localized heat at the connection joint to relieve stress.

Preferably, the method further comprises the step of applying localized heat on an area of the conduit that is adjacent to the connection joint in order to relieve stress.

Preferably, the application of localized heat heats the connection joint to a temperature between 704 ⁰ C and 816 ⁰ C. Preferably, the application of localized heat heats the connection joint to a temperature of at least 760 ⁰ C.

Preferably, the localized heat is generated by a flame. Preferably, the localized heat is generated by an induction coil. Preferably, the method further comprises the step of allowing the connection joint to air cool after the localized heat is applied.

Preferably, the localized heat is applied while the conduit and brace bar are located on a production line.

Preferably, the method further comprises the step of connecting at least one drive and at least one pick off to the conduit before the application of the localized heat. Preferably, the method further comprises the steps of forming another connection joint that connects another brace bar to the conduit and applying localized heat at the another connection joint to relieve stress.

Preferably, the method further comprises the step of applying localized heat on an area of the conduit that is adjacent to the another connection joint in order to relieve stress.

Preferably, the brace bar is generally positioned at an end of the conduit. Preferably, the method further comprises the steps of forming another connection joint that connects another brace bar to the conduit, whereby the brace bar and the another brace bar are symmetrically located on the conduit and applying localized heat at the another connection joint to relieve stress.

Preferably, the method further comprises the steps of forming another connection joint to connect the brace bar to another conduit and applying localized heat at the another connection joint to relieve stress.

Preferably, the connection joint is formed via welding.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts a perspective view of a vibrating flow device according to one embodiment of the present invention.

Figure 2 depicts a perspective view of a localized heating process using a flame. Figure 3 depicts a perspective view of a localized heating process using an induction coil.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT FIG. 1 illustrates an example of a vibrating flow device 5 in the form of a Coriolis flow meter comprising a sensor assembly 10 and one or more electronics 20. The one or more electronics 20 are connected to sensor assembly 10 via leads 100 to measure a characteristic of a flowing substance, such as, for example, density, mass flow rate, volume flow rate, totalized mass flow, temperature, and other information over path 26. The sensor assembly 10 of the present example includes a pair of flanges 101 and

101'; manifolds 102 and 102'; drive 104; pick-offs 105-105'; conduits 103A and 103B, and brace bars 120-124. Manifolds 102, 102' are affixed to opposing ends of the conduits 103 A, 103B. Drive 104 and pick-offs 105 and 105' are connected to conduits 103 A and 103B. The drive 104 is affixed to conduits 103 A, 103B in a position where the drive 104 can vibrate the conduits 103 A, 103B in opposition to one another. Pick- offs are affixed to conduits 103, 103B at opposing ends to detect the phase difference in the vibrations at opposing ends of the conduits 103 A, 103B. It should be apparent to those skilled in the art that it is within the scope of the present invention to use the principals discussed herein in conjunction with any type of vibrating flow device, including, for example, densitometers, regardless of the number of conduits, the number of drives, the number of pick-offs, the operating mode of vibration or the determined characteristic of the flowing substance.

Flanges 101 and 101' of the present example are affixed to manifolds 102 and 102' and connect conduits 103 A, 103B to a pipeline (not shown). When sensor assembly 10 is inserted into a pipeline system (not shown) which carries the flowing substance, the substance enters sensor assembly 10 through flange 101, passes through inlet manifold 102 where the total amount of material is directed to enter conduits 103 A and 103B, flows through conduits 103 A and 103B, and back into outlet manifold 102' where it exits the sensor assembly 10 through flange 101'.

Conduits 103 A and 103B are preferably selected and appropriately mounted to inlet manifold 102 and outlet manifold 102' so as to have substantially the same mass distribution, moments of inertia, and elastic modules about bending axes WW and W--W respectively. The conduits extend outwardly from the manifolds in an essentially parallel fashion. Although the conduits 103 A, 103B are shown provided with a generally U-shape, it is within the scope of the present invention to provide the conduits 103 A, 103B with other shapes, such as, for example, straight or irregular shapes.

In the present example, conduits 103 A-B are driven by drive 104 in opposite directions about their respective bending axes W and W and at what is termed the first out of phase bending mode of the flow meter. Drive 104 may comprise one of many well known arrangements, such as a magnet mounted to conduit 103 A and an opposing coil mounted to conduit 103B. An alternating current is passed through the opposing coil to cause both conduits 103 A, 103B to oscillate. A suitable drive signal is applied by one or more electronics 20, via lead 110 to drive 104.

In the present example, the one or more electronics 20 produces a drive signal and transmits it to the drive 104 via lead 110, which causes drive 104 to oscillate conduits 103 A and 103B. It is within the scope of the present invention to produce multiple drive signals for multiple drives, however. One or more electronics 20 processes left and right velocity signals from pick-offs 105, 105' to compute mass flow rate. Path 26 provides an input and an output means that allows one or more electronics 20 to interface with an operator. An explanation of the circuitry of one or more electronics 20 is unneeded to understand the present invention and is omitted for brevity of this description. Furthermore, the description of FIG. 1 is provided merely as an

example of the operation of one possible vibrating flow device and is not intended to limit the teaching of the present invention.

The embodiment shown is provided with a first pair of inner brace bars 122-123 and a second pair of outer brace bars 120-121. As shown, the inner brace bar 122 is generally located at a first end 126 of the conduits 103 A, 103B and the inner brace bar 123 is generally located at a second end 127 of the conduits 103A, 103B. Also shown, the outer brace bar 120 is generally located at the first end 126 of the conduits 103 A, 103B and the outer brace bar 121 is generally located at the second end 127 of the conduits 103A, 103B. In the embodiment depicted, each pair of the brace bars 120, 121 and 122, 123 is preferably generally positioned so that they are symmetrically located on the conduits 103 A, 103B. Although, the present example is provided with a first set 122, 123 and a second set 120, 121, it is within the scope of the present invention to provide any number of brace bars, such as, for example, a single set 122, 123 or 120, 121. As shown in FIG. 1, the brace bars 120-123 are connected to the conduits 103 A,

103B via connection joints 125. The brace bars 120-123 are typically welded to the conduits 103 A, 103B via a Gas Tungsten Arc Welding process, however, it is within the scope of the present invention to utilize other welding processes, such as, for example, Flux Cored Arc Welding process, Gas Metal Arc Welding process, or to braze or solder the brace bars 120-123 to the conduits 103A, 103B.

According to one aspect of the present embodiment, after the brace bars 120-123 are connected to the conduits 103 A, 103B, a localized heating process is used to relieve stress at the connection joints 125 and strengthen the connection joints 125. According to another aspect of the present embodiment, after the brace bars 120-123 are connected to the conduits 103 A, 103B, a localized heating process may be used to relieve stress on areas of the conduits 103 A, 103B located adjacent to the connection joints 125 and to strengthen areas on the conduits 103A, 103B located adjacent to the connection joints 125.

It is within the scope of the present invention to use any source of heat in the localized heating process. By way of example and not limitation, FIG. 2 shows a localized heating process using a flame, such as, for example, from a torch 200, and FIG. 3 shows a localized heating process that uses an induction coil 300 that is

positioned around the connection joints 125 and/or areas of the conduits 103 A, 103B that are adjacent to the connection joints 125. As shown in FIG. 3, the basic components of an induction heating system are an AC power supply 301 and the induction coil 300. Those of ordinary skill in the art will appreciate that the power supply 301 sends alternating current through the coil, generating a magnetic field. When the connection joints 125 and/or areas of the conduits 103 A, 103B that are adjacent to the connection joints 125 are placed in the coil 300, as is the case in FIG. 3, the magnetic field induces eddy currents in the connection joints 125 and/or areas of the conduits 103A, 103B that are adjacent to the connection joints 125, which, in turn, generates precise amounts of localized heat without requiring physical contact with the coil 300.

Regardless of the source of heat, the localized heating process allows strengthening and stress relief to occur by heating only the connection joints 125 and/or the areas on the conduits 103 A, 103B that are adjacent to the connection joints 125. In the present embodiment, it is the connection joints 125 and/or the areas on the conduits 103A, 103B adjacent to the connection joints 125 that may be heated to a temperature in the range of 704 ⁰ C to 816°C, and, preferably, to a temperature of at least 760 ⁰ C. According to another aspect of the present embodiment, once the localized heating process is performed the conduits 103 A, 103B and brace 120-123 assembly may be allowed to air cool; however, alternative methods of cooling are within the scope of the present invention, such as, for example, forced air or quenching.

Accordingly, the present method allows stress to be relieved without the use of an oven. Furthermore, according to the preferred aspects of the present method, the sensor assembly 10 may be assembled, although not necessarily so, without requiring the conduits 103 A, 103B and brace 120-123 assembly to be removed from a production line for purposes of stress relief and cooling. Furthermore, according to the present method it is also possible, but not necessary, to perform the localized heating process after other components, such as the drive 104 or pick-offs 105, 105' have been assembled onto the conduits 103 A, 103B, thereby not interrupting the assembly process with a stress relieving process.

The present description depicts specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the invention. For example, although the specific examples disclosed in FIGS. 1-3 show a pair of conduits 103 A, 103B, it is within the scope of the present invention to utilize any number of conduits. By way of example and not limitation, it is within the scope of the present invention to utilize a single conduit, such as, for example, conduit 103 A or 103B and connect this conduit to a supporting structure using at least one brace bar. The brace bar may be integral to the supporting structure or connected to the supporting structure via any manner, including, but not limited to welding, brazing or soldering. Persons skilled in the art will recognize that certain elements of the above- described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the above- described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the invention. Thus, although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. The teachings provided herein may be applied to other embodiments than those described above and shown in the accompanying figures. Accordingly, the scope of the invention is determined from the following claims.