JPH07159210A - Measuring pipe for electromagnetic flowmeter - Google Patents

Abstract

PURPOSE:To perform butt-joining while aligning the centers of a pipe and a flange ring correctly without requiring any jig. CONSTITUTION:The joining part A between the pipe 1A of a measuring pipe 1 and flange rings 1B, 1C is butt-welded. Protrusions 21, 22 are provided on the outer peripheral face of a reinforcing pipe 3 and brought into tight contact with the inner peripheral face at the joining part A thus centering the pipe 1A and the flange rings 1B, 1C. Subsequently, the joining part A is welded thus joining the protrusions 21, 22 to the measuring pipe 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring tube for an electromagnetic flow meter which measures the flow rate of a conductive fluid.

[0002]

2. Description of the Related Art An electromagnetic flow meter (Japanese Utility Model Publication No. 2-28411, etc.) measures the flow rate of a conductive fluid flowing in a measuring pipe by utilizing the principle of electromagnetic induction, and is a signal generated in the fluid. In order to prevent a short circuit between the electromotive force and the measuring tube made of a non-magnetic material such as stainless steel, the inner wall surface, which is the liquid contact surface of the measuring tube, and the flange outer surface are usually covered with a lining material. Since the lining material is required to have excellent heat resistance, corrosion resistance, and insulation, an insulating material such as fluororesin is usually used and is lined on the inner wall surface of the measuring tube and the outer surface of the flange by a centrifugal method. It However, since the lining material made of fluororesin has poor adhesion to metal and is easily peeled off from the measuring tube, the lining material 2 lined on the inner wall of the measuring tube 1 is usually reinforced by the reinforcing tube as shown in FIG. 3 is embedded to prevent peeling of the lining material 2 (example: Jikken 2-2622).
No. 5). The measuring pipe 1 is composed of a pipe 1A whose both ends are open and flange-shaped rings 1B and 1C which are joined to the openings of both ends of the pipe 1A by welding 4, respectively. The reinforcing pipe 3 is a perforated pipe such as SUS, and the measuring pipe 1
A cylindrical body 3A of a non-magnetic material, which is arranged coaxially therewith,
Perforated disk 3 of magnetic material that is integrally provided at both ends of the cylindrical body 3A and that faces the respective flanges 1B and 1C of the measuring tube 1 in parallel.
B, 3C, a cylindrical body 3A, a porous disc 3B, 3
C is welded and fixed to the spacer 5 provided on the inner wall surface of the measuring tube 1 and the flange end surface. The porous discs 3B and 3C are
The peeling of the lining material 2 covering the flange end surface is prevented, and the magnetic flux of the exciting coil 6 is applied to the flanges 1B, 1B.
Leakage from C along the axial direction of the measuring tube 1 is prevented. Reference numeral 7 denotes a pair of electrodes (only one of which is shown) penetrating through the center of the wall of the measuring tube 1 so as to be orthogonal to the magnetic field generated by the exciting coil 6, and 9 denotes a core that covers the outer circumference of the exciting coil 6.
Reference numeral 0 is a signal lead wire of the electrode 7, and 11 is a cover that covers the outer circumference of the measuring tube 1.

[0003]

When the conventional measuring pipe 1 is manufactured, the pipe 1A and the flange-shaped rings 1B and 1C are butt-welded at the joint A between the pipe 1A and the flange-shaped rings 1B and 1C. Since it is necessary to correctly align the centers of the pipes 1A and the flange-shaped rings 1B, 1C, the outer diameter and the inner diameter of the joint portion A are matched by a jig, and after temporary welding, main welding is performed to make the pipe 1A,
The flanged rings 1B and 1C were integrally joined to manufacture the measuring tube 1. After the measurement pipe 1 was manufactured, the reinforcing pipe 3 was inserted into the measurement pipe 1 via the spacer 5, and the spacer 5 was welded to the measurement pipe 1. However, as described above, in the conventional measuring tube 1 by butt welding, a jig and tack welding are required, and the workability is extremely poor,
There was a problem of low productivity.

Therefore, as a method for solving such a problem, as shown in FIG. 4, spigots 12a and 12b are provided on the joint end faces of the pipe 1A and the flange ring 1B, and the spigots are fitted to the pipe 1A by flange fitting. A measuring tube in which the centers of the rings 1B are aligned and welded is also known. According to such a spigot type measuring tube, there is an advantage that a jig is not required at the time of manufacturing,
Since the steps 14 are formed on the joint end faces by the spigots 12a and 12b, it is difficult to completely melt-bond the entire thickness of the joint A and there is a problem in strength. Further, there is also a problem that a manufacturing process becomes high because a step for spigot processing is required.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to bring the pipe and the flange-shaped ring into a correct butting position without using a jig. Can be joined,
An object of the present invention is to provide a measuring tube for an electromagnetic flow meter, which ensures strength and improves workability.

[0006]

In order to achieve the above object, the present invention connects a flange-shaped ring to each opening of both ends of a cylindrical pipe, and reinforces the inner circumference of the pipe and the flange-shaped ring. In a measuring pipe for an electromagnetic flow meter, which is provided with a pipe and is lined to cover the reinforcing pipe, a joint portion of the pipe and the flange ring is formed in a butt weld shape, and a protruding portion provided on the outer periphery of the reinforcing pipe is formed. The joint is made to correspond to the joint, and the connecting portion is welded together with the protrusion.

[0007]

In the present invention, the protrusions of the reinforcing pipe are brought into contact with the inner peripheral surface of the joint between the pipe and the flange-shaped ring to center them. Further, the protrusion is welded to the weld when the joint between the pipe and the flange ring is welded.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a sectional view of a measuring pipe for an electromagnetic flow meter according to the present invention, and FIG. 2 is a perspective view of a reinforcing pipe. In the figure, the same components as those in FIGS. 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted. In the present embodiment, the joint end surfaces of the pipe 1A and the flange-shaped rings 1B and 1C are formed into a flat surface orthogonal to the axis to form a butt-welding type. By providing strip-shaped protrusions 21 and 22 integrally on the surface and closely contacting these protrusions 21 and 22 with the inner peripheral surface of the joint A, and by making the centers of the pipe 1A and the flange-shaped rings 1B and 1C coincide with each other, The reinforcing pipe 3 itself has a function as a centering jig for the pipe 1A and the flange-shaped rings 1B, 1C. The outer diameters of the protrusions 21 and 22 are set to be substantially equal to the inner diameter of the measuring tube 1.

In this case, although the projections 21 and 22 are provided over the entire circumference of the cylindrical body 3A in this embodiment, they may be discontinuous. When the measuring tube 1 has a long overall length, it is advisable to provide the protrusion 23 also at the center of the cylindrical body 3A in order to stabilize the measuring tube 1. Further, in this embodiment, the protrusions 21 and 2 are
Although 2 and 23 are formed integrally with the cylindrical body 3A, they may be separately manufactured and fitted and fixed to the outer peripheral surface of the cylindrical body 3A. The protrusions 21, 22, and 23 are connected to the pipe 1A and the flange-shaped ring 1B by inserting the reinforcing pipe 3 into the measuring pipe 1 before welding and abutting the inner peripheral surface of the joint A. 1C is centered, and in this state, the reinforcing pipe 3 is temporarily joined to the inner peripheral surface of the joint A by spot welding. Thereafter, the joint A is welded to integrally join the pipe 1A, the flange-shaped rings 1B and 1C, and the protrusions 21 and 22, and then the lining material 2 is lined and the reinforcing pipe 3 is covered. 1 can be obtained.

Thus, the measuring tube 1 having such a structure
In this case, the reinforcing pipe 3 is fitted into the measuring pipe 1 before welding, and the projections 21 and 22 are attached to the pipe 1A and the flange-shaped ring 1B.
When closely contacting the inner peripheral surface of the joint portion of 1C, these protrusions 21,
22 makes it possible to match the centers of the pipe 1A and the flange-shaped rings 1B, 1C. Therefore, regardless of the butt welding, the pipe 1A and the flange-shaped rings 1B and 1C can be coaxially joined without using a centering jig, and the workability can be improved. In the butt-joining, unlike the spigot portion, no step is formed on the joint surface, so that the entire thickness of the joint portion A, and further the protrusions 21 and 22 can be joined to the joint portion A. The strength can be increased.

[0011]

As described above, according to the measuring pipe for an electromagnetic flowmeter of the present invention, the joining portion between the pipe and the flange ring is formed into a butt welded shape, and the reinforcing pipe is inserted into the measuring pipe. Since the protrusion is provided on the outer periphery so as to be in close contact with the joint and the protrusion and the centering function of the pipe and the flange ring are provided, the pipe and the flange ring can be coaxially joined without using a jig. The workability can be improved. In the butt welding, not only the joining end face can be easily processed, but also the entire wall thickness can be completely melted and welded, so that the reinforcing pipe can be joined to the joining portion and the strength can be easily secured. Furthermore, the protrusion of the reinforcing pipe functions as a backing for preventing the molten metal from dropping during welding, and a good welding bead can be obtained, which is a great effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a measuring tube for an electromagnetic flow meter according to the present invention.

FIG. 2 is a perspective view of a reinforcing pipe.

FIG. 3 is a sectional view of a conventional measuring tube for an electromagnetic flow meter.

FIG. 4 is a sectional view of a spigot portion.

[Explanation of symbols]

 1 Measuring Tube 1A Pipe 1B Flange Ring 1C Flange Ring 2 Lining Material 3 Reinforcing Tube 5 Spacer 6 Excitation Coil 7 Electrode 21 Protrusion 22 Protrusion 22 A Joint

Claims (1)

[Claims] 1. A flanged ring is connected to each opening of both ends of a pipe formed in a cylindrical shape, a reinforcing pipe is arranged on the inner circumferences of the pipe and the flanged ring, and a lining is provided to cover the reinforcing pipe. In the measuring pipe for the electromagnetic flowmeter, the joint portion of the pipe and the flange-shaped ring is formed in a butt-welding shape, and the protrusion portion provided on the outer periphery of the reinforcing pipe is made to correspond to the joint portion, and this connecting portion is the protrusion portion A measuring tube for an electromagnetic flowmeter, which is welded together.