JP3340355B2 - Measuring tube for electromagnetic flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring pipe for an electromagnetic flowmeter for measuring a flow rate of a conductive fluid flowing in a pipe.

[0002]

2. Description of the Related Art An electromagnetic flowmeter for measuring the flow rate of a conductive fluid flowing in a measuring tube by utilizing an electromagnetic induction phenomenon (Jitsuho 2-
No. 28411), in order to prevent a short circuit between an electromotive force generated in a fluid to be measured and a measuring tube formed of a nonmagnetic material such as stainless steel, an inner wall surface which is a liquid contact surface of the measuring tube is usually used. And the outer surface of the flange is covered with a lining material. As the material of the lining material is required to be excellent in heat resistance, corrosion resistance, and insulation, an insulating material such as fluororesin is usually used, and is formed on the inner wall surface and the flange joint surface of the measurement tube by injection molding. . However, since the lining material has poor adhesion to metal and is easily peeled off from the measuring tube, a reinforcing tube formed by a perforated plate is usually embedded in the lining material covering the inner wall of the measuring tube. In addition to preventing peeling, the deformation of the lining material due to a change in temperature or pressure in the measurement tube is prevented (eg, Japanese Utility Model Publication No. 2-26025, Japanese Utility Model Publication No. 2-5191, and Japanese Utility Model Publication No. 1-7918).
No.).

FIG. 4 shows a conventional example of this type of electromagnetic flow meter. 1 is a measuring pipe, 2 is a lining material, and 3 is a reinforcing pipe buried in the lining material 2. The measurement pipe 1 is composed of a pipe 1A formed of a straight pipe open at both ends and forming a flow path 4, and two flanged pipes 1B and 1C joined to both ends of the pipe 1A by welding 12, respectively. I have.
The tube 1A and the flanged pipes 1B and 1C are made of a non-magnetic material such as SUS. The reinforcing pipe 3 is also made of a non-magnetic material such as SUS and has many through holes 3.
a, and is fixed in the measuring tube 1 via a ring-shaped spacer 5. The welding order of the reinforcing pipe 3 and the spacer 5 is generally such that the spacer 5 is spot-welded to the reinforcing pipe 3 and then spot-welded to the pipe 1A. 5 may be spot-welded.

Reference numeral 6 denotes a pair of saddle-type exciting coils for forming a magnetic field in a direction perpendicular to the flow direction of the fluid 10 to be measured. The saddle-type exciting coils 6 are provided on the outer wall of the measuring tube 1 so as to face up and down. It is covered by the core 11. Reference numeral 7 denotes a pair of electrodes (only one of which is shown) penetratingly mounted at the center of the tube wall of the measuring tube 1 so that the axis is orthogonal to the magnetic field generated by the exciting coil 6, and the inner end of the electrode 7 passes through the lining material 2. Thus, it faces the flow path 4 and forms a liquid contact surface with the fluid 10 to be measured.
13 is a signal lead wire of the electrode 7, 14 is a cover for covering the outer periphery of the measuring tube 1, 15 is a tube 1A and a pipe 1 with a flange.
B, 1C.

In such a configuration, when the excitation coil 6 is energized to flow the conductive fluid 10 to be measured into the measuring tube 1, a space between the pair of electrodes 7 which are respectively orthogonal to the magnetic field direction and the fluid flow direction. Generates an electromotive force proportional to the average flow rate,
By detecting this, the flow rate of the fluid can be measured.

In order to manufacture the measuring tube 1, first, the joining portion 15 of the pipe 1 A and the pipes 1 B and 1 C with flanges is butt-welded to obtain the measuring tube 1. On the other hand, for example, there is a method in which the end of the pipe is fitted to a disc-shaped flange and welding is performed. In this method, TIG welding is usually performed. Welding must be performed on both sides, and welding is performed by further filling the wall, so that distortion due to welding is likely to occur, which is not preferable. On the other hand, butt welding requires only one welding point, has the advantage that electron beam welding with high thermal energy is possible due to the ease of welding, and distortion is unlikely to occur.

Next, the spacer 5 is fixed to the inner wall surface of the measuring tube 1 by welding, and then the reinforcing tube 3 is spot-welded to the spacer 5. This spot welding is for preventing the lining material 2 from shifting due to the injection pressure during injection molding. Thereafter, the measuring tube 1 is loaded into a molding die, the lining material 2 is injection-molded from one direction of the axis, and the reinforcing tube 3 is formed.
Mold. The order of welding the reinforcing pipe 3 and the spacer 5 is as follows.
After welding to C, the reinforcing pipe 3 may be spot-welded to the spacer 5.

[0008]

In the production of the conventional measuring tube 1 described above, the pipe 1A and the pipe 1 with the flange are used.
B and 1C were integrally joined by butt welding. However, the pipe 1A and the flanged pipe 1
When the pipes B and 1C are abutted with each other, it is difficult to make the axes of the pipes 1B and 1C with flanges coincide with the pipe 1A with high accuracy, and there is a problem that the lining material 2 is easily peeled off. That is, the pipe 1A and the flanged pipe 1
In order to make the axes B and 1C coincide with each other, a jig 20 similar to a double jack as shown in FIG. 5 is usually used.
For example, in the case of a measuring tube having a diameter of 200 mm, eccentricity of up to about 0.5 mm is inevitably generated due to mechanical deviation and roundness of the tube. The thickness of the spacer 5 is 0.4 to 0.5 mm
The pipe 1A and the flanged pipe 1B,
When 1C is eccentric, the gaps between the reinforcing pipe 3 and the pipes 1B and 1C become uneven in the circumferential direction, and in the worst case, a part of the reinforcing pipe 3 is formed as a flanged pipe 1B, 1 as shown in FIG.
It becomes impossible to secure the minimum gap for the lining material 2 by contacting the inner wall surface of C. As a result, even if the lining material 2 is filled, the lining material 2 does not wrap around between the reinforcing pipe 3 and the pipes 1B and 1C in a portion where the gap is narrow, and the adhesion with the reinforcing pipe 3 is poor, which causes peeling.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method in which even if a pipe body and a flanged pipe are eccentric, the distance between the flanged pipe and the reinforcing pipe is reduced. The minimum gap for the lining material can be reliably secured, and the lining material 2 can be peeled off.
An object of the present invention is to provide a measuring pipe for an electromagnetic flowmeter which prevents deformation and the like.

[0010]

In order to achieve the above object, a measuring pipe for an electromagnetic flow meter according to the present invention comprises a pipe forming a flow path and two flanges welded to both ends of the pipe, respectively. A measuring pipe is constituted by a pipe with a pipe, and a reinforcing pipe consisting of a perforated pipe is buried at a required interval from the measuring pipe in a measuring pipe for an electromagnetic flowmeter in a lining material lined on an inner wall surface of the measuring pipe. The inner diameter of the pipe is set smaller than the inner diameter of the flanged pipe, and the intermediate portion of the reinforcing pipe is fixed to the inner wall surface of the pipe via a spacer. In the present invention, since the inner diameter of the pipe is smaller than the inner diameter of the flanged pipe and the spacer is fixed to the inner wall surface of the pipe, even if the pipe and the flanged pipe are eccentric, the flanged pipe is A gap for the lining material can be secured between the reinforcing pipe and the reinforcing pipe. Therefore, the lining material wraps around the inside of the reinforcing pipe, and adheres well to the reinforcing pipe, and does not peel or deform.

Further, the present invention provides a tube forming a flow path,
A measuring pipe is constituted by two flanged pipes which are respectively welded to both ends of the pipe body, and a reinforcing pipe made of a perforated pipe is provided in a lining material lined on an inner wall surface of the measuring pipe with the measuring pipe and a required pipe. In the measuring pipe for the electromagnetic flow meter embedded at intervals, the inner diameter of the flanged pipe is set smaller than the inner diameter of the pipe body, and the end of the reinforcing pipe is placed on the inner wall surface of the flanged pipe via a spacer. It is characterized by being fixed. In the present invention, since the inner diameter of the flanged pipe is smaller than the inner diameter of the pipe body and the spacer is fixed to the inner wall surface of the flanged pipe, even if the pipe body and the flanged pipe are eccentric, the flanged pipe and A gap for the lining material can be secured between the reinforcing pipe and the reinforcing pipe. Therefore, the lining material wraps around the inside of the reinforcing pipe, adheres well to the reinforcing pipe, and does not peel or deform.

Further, the present invention is characterized in that the pipe body and the flanged pipe are joined by butt welding, and the difference in inner diameter between the pipe body and the flanged pipe is set to be larger than the maximum eccentricity at the time of joining. In the present invention, since the inner diameter difference between the pipe and the flanged pipe is set to be larger than the maximum eccentricity generated at the time of joining, the reinforcing pipe does not hit the inner wall surface of the flanged pipe. Therefore, the lining material wraps around the inside of the reinforcing pipe, adheres well to the reinforcing pipe, and does not peel or deform.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a cross-sectional view showing one embodiment of a measuring pipe for an electromagnetic flowmeter according to the present invention.
In the drawings, the same components as those shown in the section of the prior art are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the present embodiment, the inner diameter of the tube 1A is set smaller than the inner diameters of the flanged pipes 1B and 1C,
The reinforcing tube 3 is fixed to the inner wall surface of the tube 1A via the spacer 5. The difference between the inner diameters of the pipe 1A and the flanged pipes 1B and 1C is the maximum eccentricity d generated when the pipe 1A and the flanged pipes 1B and 1C are joined by butt joining (d = about 0.5 mm in the case of butt joining). ) Is preferably set larger. The outer diameters of the pipe 1A and the flanged pipes 1B and 1C are equal. Other structures are the same as the conventional structure shown in FIG.

FIG. 2 is an exaggerated sectional view showing a state in which the pipe and the flanged pipe are eccentrically joined. The maximum eccentricity d generated when the pipe 1A and the flanged pipes 1B and 1C are joined by butt joining is 0.5 m.
m, but the pipe 1A and the flanged pipe 1B,
Since the inner diameter difference of 1C is set to be larger than this, even if the pipe body 1A and the flanged pipes 1B and 1C are eccentric about 0.5 mm, a part of the reinforcing pipe 3 contacts the flanged pipes 1B and 1C. Therefore, a sufficient annular gap for filling the lining material 2 between the flanged pipes 1B and 1C and the reinforcing pipe 3 can be ensured. Therefore, the lining material 2 wraps around the inside of the reinforcing pipe 3 and adheres well to the reinforcing pipe 3, and there is no risk of peeling or deformation.

FIG. 3 is a sectional view showing another embodiment of the present invention. In this embodiment, the inner diameters of the flanged pipes 1B and 1C are set smaller than the inner diameter of the tubular body 1A, and the reinforcing pipe 3 is interposed between the flanged pipes 1B and 1C via the spacer 5 in contrast to the above embodiment. It is fixed to the inner wall. It is preferable that the inner diameter difference between the pipe 1A and the flanged pipes 1B and 1C is set to be larger than the maximum eccentricity d generated when the pipe 1A and the flanged pipes 1B and 1C are joined by butt joining. The outer diameters of the pipe 1A and the flanged pipes 1B and 1C are equal.

In such a configuration, since the spacer 5 is fixed to the flanged pipes 1B and 1C, even if the pipe 1A and the flanged pipes 1B and 1C are eccentrically joined to each other, the flanged pipe 1B is joined. ,
An annular gap equal to the thickness of the spacer 5 can be secured over the entire circumference between the tube 1A and the tube 1A. Therefore, the lining material 2 wraps around the inside of the reinforcing pipe 3 and adheres well to the reinforcing pipe 3, and there is no risk of peeling or deformation.

In each of the above-described embodiments, the reinforcing pipe 3 and the spacer 5 are formed as separate members. However, the present invention is not limited thereto. Alternatively, a protrusion may be integrally provided on the base, and this protrusion may be used as a spacer.

[0018]

As described above, according to the present invention, the inner diameter of the pipe is set smaller than the inner diameter of the pipe with the flange, and the reinforcing pipe is fixed to the inner wall surface of the pipe via the spacer. Therefore, even when the flanged pipe is eccentrically welded, a gap for filling the lining material between the flanged pipe and the reinforcing pipe can be secured. Therefore, the adhesion between the lining material and the reinforcing pipe is good, and peeling and deformation of the lining material can be prevented.

In the present invention, the inner diameter of the flanged pipe is set smaller than the inner diameter of the pipe body, and the reinforcing pipe is fixed to the inner wall surface of the flanged pipe via the spacer.
Even when the flanged pipe is eccentrically welded to the pipe body, a constant gap in the circumferential direction for filling the lining material between the flanged pipe and the reinforcing pipe can be ensured. Therefore, the adhesion between the lining material and the reinforcing pipe is good, and peeling and deformation of the lining material can be prevented.

Further, according to the present invention, the pipe and the flanged pipe are joined by butt welding, and the inner diameter difference between the pipe and the flanged pipe is set to be larger than the maximum eccentricity at the time of joining. Even when the flanged pipe is eccentrically welded, the reinforcing pipe does not come into contact with the flanged pipe, and a gap for filling the lining material between the reinforcing pipe and the pipe can be secured. . Further, since it is only necessary to make the inner diameters of the pipe body and the flanged pipe different, the structure is simple, and the pipe can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a measurement pipe for an electromagnetic flowmeter according to the present invention.

FIG. 2 is a cross-sectional view showing a state in which a pipe and a flanged pipe are eccentrically joined.

FIG. 3 is a cross-sectional view showing another embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional example of an electromagnetic flowmeter.

FIG. 5 is a view showing a butt joint of a pipe and a flanged pipe.

FIG. 6 is a cross-sectional view showing a state where the pipe and the flanged pipe are eccentrically joined together.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Measurement pipe, 1A ... Pipe body, 1B, 1C ... Flanged pipe, 2 ... Lining material, 3 ... Reinforcement pipe, 5 ... Spacer,
6 ... electrode, 7 ... excitation coil, 20 ... jig.

Claims (3)

(57) [Claims] 1. A measuring pipe is composed of a pipe forming a flow path and two pipes with flanges welded to both ends of the pipe, respectively, and a lining material lined on an inner wall surface of the measuring pipe. In a measuring pipe for an electromagnetic flowmeter, a reinforcing pipe made of a perforated pipe is buried at a predetermined interval from the measuring pipe, the inner diameter of the pipe is set smaller than the inner diameter of the flanged pipe, and the reinforcing pipe is A measurement tube for an electromagnetic flowmeter, wherein an intermediate portion is fixed to an inner wall surface of the tube via a spacer. 2. A measuring pipe is constituted by a pipe forming a flow path and two pipes with flanges welded to both ends of the pipe, respectively, and a lining material lined on an inner wall surface of the measuring pipe. In an electromagnetic flowmeter measuring pipe in which a reinforcing pipe made of a perforated pipe is buried at a predetermined interval from the measuring pipe, the inner diameter of the flanged pipe is set smaller than the inner diameter of the pipe body, and the reinforcing pipe is A measurement pipe for an electromagnetic flowmeter, wherein an end is fixed to an inner wall surface of the pipe with a flange via a spacer. 3. The measuring pipe for an electromagnetic flowmeter according to claim 1, wherein the pipe and the flanged pipe are joined by butt welding, and a difference in inner diameter between the pipe and the flanged pipe is determined to be a maximum eccentricity at the time of joining. A measuring tube for an electromagnetic flow meter, wherein the measuring tube is set to be larger than the amount.