JP4291666B2 - Pressure measuring device for fluid in pipe line - Google Patents

Description

  The present invention relates to an in-line type pressure measuring device that detects a pressure of a fluid flowing in a pipe line using a pressure change of a pressure-receiving fluid that is in a non-contact state with the fluid, and particularly, the amount of the pressure-receiving fluid is reduced. The pressure of the fluid in the pipeline that makes it possible to measure the pressure change with high accuracy and is less affected by the temperature of the fluid flowing through the pipeline whose pressure is to be measured, and to improve the durability of the inner tube The present invention relates to a measuring device.

Conventionally, as one form of an in-line type pressure measuring device incorporated in a pipe, a pressure receiving fluid is sealed behind a thin-film pressure receiving portion having an inner peripheral surface shape continuous with the inner peripheral surface of the pipe, and the pressure receiving fluid There is a type that detects the pressure received by a pressure gauge. An example thereof is shown in FIGS.
As shown in the cross section of FIG. 5, the conventional form of such a pressure measuring device is an outer tube made of a corrosion-resistant alloy such as thick stainless steel provided with flanges a and b projecting radially inward at both axial ends. c, an inner pipe d made of a corrosion-resistant alloy such as thin stainless steel, the outer peripheral surface of the axial direction end being welded to the inner peripheral surface of the flanges a and b of the outer pipe c and arranged radially inside the outer pipe c; The annular pressure receiving fluid enclosing portion e formed between the outer tube c and the inner tube d and a pressure gauge f connected to the pressure receiving fluid enclosing portion e are configured. For welding the outer tube c and the inner tube d, a welding method using a high-density energy heat source such as electron beam welding is usually used.

By the way, since the inner pipe d functions as a diaphragm that bends due to the pressure of the fluid in the pipe line, the inner pipe d is configured to be extremely thin and usually has a thickness of about 0.04 to 0.07 mm. Therefore, as shown in an enlarged view of the welded portion in FIG. 6, the welded portion g obtained by a welding method using a high-density energy heat source such as electron beam welding extends to the inner diameter corner portion h of the inner tube d. h drifts due to melting. In addition, since it is thin, distortion and property deterioration of the inner tube d, which is subjected to a large heat load during welding, also increase.
Further, it is difficult to secure a sufficient welding depth at the welded portion on the inner pipe d side, and a crevasse (unwelded portion) remains at the tip of the weld bead, and it is difficult to keep the welding strength high. And when the drooping of the corner portion h occurs in this way, when the pressure measuring device is incorporated into the pipe line, only a portion of the inner peripheral surface of the pipe line is formed with a depression or an unevenness, and the pipe fluid flows there. It becomes easy to stay.
Such fluid retention not only increases duct resistance, but also causes bacterial growth and contaminants retention, so chemicals, foods, physics, semiconductors, etc., where the fluid in the tube must be kept highly hygienic. In the case of a fluid related to the production of such substances, it is not preferable.
In addition, the pressure receiving fluid enclosed in the pressure receiving fluid enclosing portion is affected by the temperature change of the fluid or the like flowing through the pipe line whose pressure is to be measured. Therefore, the more the pressure-receiving fluid sealed in the pressure-receiving fluid sealing portion formed between the outer tube and the outer peripheral surface of the inner tube, the larger the volume expansion amount of the pressure-receiving fluid. There was a problem that it was difficult to measure the pressure change of accuracy.
Furthermore, since the inner tube has a function as a diaphragm, the thickness of the inner tube is as thin as about 0.04 to 0.08 mm as described above. However, when a pressure load equal to or higher than the set pressure is applied to the inner pipe temporarily or constantly, the inner pipe is distorted by this overload.

By the way, in consideration of the problems of the conventional pressure measuring device for fluid in a pipe, the applicant of the present application first prevented the inner pipe corner from being bent due to welding of the inner pipe to the outer pipe. A pressure measuring device for fluid in a pipe line that can ensure welding between pipes has been proposed (see Patent Document 1).
However, even in this pressure measuring device for fluid in the pipe line, the durability of the inner pipe was not sufficient.
Japanese Patent Laid-Open No. 9-243485

  In view of the problems of the conventional pressure measuring device for fluid in a pipe, the present invention reduces the amount of pressure receiving fluid and is influenced by the temperature of the fluid flowing through the pipe that is the target of pressure measurement. It is an object of the present invention to provide a pressure measuring device for fluid in a pipe that is difficult to measure pressure changes with high accuracy and improves the durability of the inner pipe.

To achieve the above object, a pressure measuring device of the conduit in the fluid of the present invention includes an outer tube of thick, thick projecting radially outwardly in the axial direction both ends of the body portion and the body portion of thin-walled A flange portion of the meat is provided, and the outer peripheral surface of the flange portion is welded to the inner peripheral surface of the outer tube, and is disposed between the outer tube and the main body portion of the inner tube. In the pressure measuring device for fluid in a pipe line, which is formed of an annular pressure receiving fluid enclosing part and a pressure gauge connected to the pressure receiving fluid enclosing part, a substantial part of the pressure receiving fluid enclosing part is provided on the outer periphery of the main body of the inner pipe. with reducing the internal volume, to protect the inner tube from acting on the inner tube load, the plate cross section characterized by being fitted with spacers formed by winding such that the circular.

  In this case, the spacer can be made of an aluminum plate.

According to the pressure measuring apparatus of the conduit in the fluid of the present invention, by fitted a spacer on the outer periphery of the main body portion of the thin-walled inner tube, formed between the outer tube and the inner tube by the volume fraction of the spacer Since the amount of pressure-receiving fluid enclosed in the annular pressure-receiving fluid enclosure is reduced, the amount of change in the temperature of the pressure-receiving fluid due to the change in the temperature of the fluid flowing through the pipe that is the target of pressure measurement is reduced, and the effect of temperature change is reduced. Since it can be made difficult to receive, a highly accurate pressure change can be measured, and even if the inner tube is overloaded, it is protected by a spacer, and the durability of the inner tube can be improved.

  In addition, the spacer can be easily and accurately created by using a plate made of aluminum.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a pressure measuring device for fluid in a pipe line of the present invention will be described based on the drawings shown in FIGS.

1 to 4 show an embodiment of a pressure measuring device for fluid in a pipe of the present invention.
The pressure measuring device M for the fluid in the pipe line is fitted into the outer wall of the thick outer tube 1, the thin inner tube 2 attached so as to be inserted inward in the radial direction, and the outer peripheral portion of the inner tube 2. The spacer 3, the nipple 4 that is connected to the annular pressure-receiving fluid sealing portion 13 formed between the inner tube 2 and the outer tube 1 and can be attached with a pressure gauge, and the nipple 4 The pressure receiving fluid is sealed in the pressure receiving fluid sealing portion 13.

The outer pipe 1 is thick enough to maintain the same rigidity as other pipe parts, and is not particularly limited. For example, the outer pipe 1 is made of a corrosion-resistant alloy pipe such as stainless steel having excellent rust resistance, Flange portions 11 and 12 are formed on both end surfaces in the axial direction so as to be watertightly joined with other pipes (not shown) by an engagement tool (not shown) such as a clamp. An annular recess is formed on the inner peripheral surface between the portions 11 and 12, and this recess is configured as the pressure receiving fluid sealing portion 13.
On the connection end surfaces of the flange portions 11 and 12, packing fitting grooves 14 and 15 for fitting packing such as O-rings or gaskets are formed in order to enable watertight connection with other pipes to be connected. Further, a nipple 4 which can be attached with a pressure gauge 5 or the like so as to be electrically connected to the outer peripheral portion of the outer pipe 1 and the inside of the pressure receiving fluid sealing portion 13 is attached.

As shown in FIG. 3, the thin inner tube 2 has a function as a diaphragm, and exhibits the flexibility suitable for obtaining the desired pressure sensitivity, and is thin and excellent in corrosion resistance such as stainless steel having excellent rust prevention properties. Thick-walled portions projecting outward in the radial direction corresponding to the flange portions 11 and 12, that is, outward flange portions 21 and 22, are formed on the both ends in the axial direction of the alloy pipe. As shown in FIG. 3, the thick flange portions 21 and 22 and the connection portions 23 and 24 between the inner pipe main body portion 20 are configured so that stress is not concentrated on the connection portion between the flange portion and the inner pipe main body portion. An inclined surface is formed so that the change in the thickness becomes gentle, so that the outer shape of the inner tube 2 becomes a drum shape.
As a result, in the state of being incorporated in the pipe line, there is no depression or irregularity in the connection part with the pipe line, and the retention of fluid can be eliminated, so that the growth of bacteria and the retention of contaminants can be eliminated. it can. In addition, since a sufficient welding depth can be obtained by ensuring the thickness of the welded portion (flange portion) on the inner tube side, not only is welding ensured, but the inner tube is also subject to a large heat load during welding. The strength of welds can be improved, and the inner and outer pipe end faces, that is, the end faces of pressure measuring devices can be cut as necessary. Therefore, the cleanliness of the welded surface with the pipe line can be further improved by finishing the end face after welding of the inner and outer pipes.

  In addition, the inner diameter of the inner pipe 2 is set to a size that matches the pipe inner diameter φ to be connected, but this is not particularly limited. For example, the inner pipe is set to 10.5 to 70 mm and serves as a pressure receiving portion. When the wall thickness t0 of the main body 20 is about 0.04 to 0.08 mm as in the conventional case and the axial length L is, for example, 60 mm, the radial thickness t1 of the axial end is About 0.3 to 0.4 mm and the axial width t2 of the outward flange portions 21 and 22 are preferably about 3 to 4 mm.

In addition, on the outer peripheral surface of the inner tube 2, more specifically, on the outer peripheral surface of the inner tube main body portion 20 excluding the outward flange portions 21 and 22 of the inner tube 2 and the connecting portions 23 and 24 formed of inclined surfaces, As shown in FIGS. 1 and 4, the spacer 3 is inserted.
The spacer 3 is not particularly limited. For example, the spacer 3 is formed using a single aluminum plate having a thickness of about 0.10 mm to 0.30 mm (in this embodiment, a thickness of 0.15 mm). It is formed by winding so that the cross-sectional shape is circular, and this is inserted into the outer peripheral surface of the inner tube 2 or the aluminum plate is wound around the outer peripheral surface of the inner tube main body 20 in a single circular shape. It is inserted into the outer peripheral surface of the inner tube 2.
As a result, even when the inner pipe 2 is overloaded with the liquid flowing through the pipe line, the spacer 3 reinforces the inner pipe 2 and improves the durability of the inner pipe 2. In addition, since the spacer 3 is inserted into the pressure receiving fluid sealing portion 13, the substantial internal volume of the pressure receiving fluid sealing portion 13 is reduced only by the main body portion of the spacer 3, so that the pressure receiving fluid sealing portion 13 is sealed. This reduces the amount of pressure receiving fluid.
Furthermore, the pressure-receiving fluid sealed in the pressure-receiving fluid sealing portion 13 is also affected by the temperature of the fluid flowing through the pipe line whose pressure is to be measured. However, since the volume of the pressure-receiving fluid encapsulated in the pressure-receiving fluid enclosing portion 13 is reduced, the volume expansion amount of the pressure-receiving fluid accompanying the temperature change can be reduced, so that the pressure change can be measured with high accuracy. it can.

  As shown in an enlarged view of one welded portion (the same applies to the welded portion on the opposite side) in FIG. 2, the inner and outer peripheral surfaces of the flange portions 11 and 21 of the outer tube 1 and the inner tube 2 are in contact with each other. The portions are welded from the end face sides of both tubes 1 and 2 using a welding method using a high-density energy heat source such as electron beam welding. The welded portion W formed in this way has a wedge-shaped cross section with the outer side widened, as shown by hatching in the figure, but the thickness of the outward flange portion 21, that is, the difference between the inner and outer radii is sufficiently wide. Therefore, the end portion of the welded portion W spreading in the inner diameter direction does not reach the inner peripheral surface portion of the inner tube 2, and distortion of the inner tube end portion due to welding is reduced.

Thus, a sealed pressure-receiving fluid sealing portion 13 is formed between the inner and outer peripheral surfaces sandwiched between the flange portions 11, 12, 21, and 22 at both axial ends of the outer tube 1 and the inner tube 2. An appropriate pressure receiving fluid is sealed in the pressure receiving fluid sealing portion 13.
The pressure receiving fluid sealing portion 13 is connected to the pressure gauge 5 via a joint such as a nipple 4 welded to a hole 16 formed through the peripheral wall of the outer tube 1 in the radial direction. The pressure of the pressure receiving fluid can be applied to the pressure gauge 5.

  As mentioned above, although the pressure measuring apparatus of the fluid in a pipe line of the present invention was explained based on one embodiment materialized by combination of a suitable form which can be assumed, the present invention is limited to an example concrete composition. Instead, various specific configurations can be adopted within the scope of the matters described in the individual claims. For example, a flange is formed so as to protrude from both ends of the outer pipe, and a flange is formed so as to protrude from the outer circumference of the pipe as well, and a bolt is provided between both flanges of the outer pipe 1 and the pipe. The configuration can be changed as appropriate within a range not departing from the gist of the invention, such as a form of connection by stopping.

  The pressure measuring device for fluid in a pipe of the present invention has a characteristic of measuring a pressure change of a pressure-receiving fluid in a non-contact state with a fluid flowing through the pipe, so that bacterial growth and contaminant retention For example, it can also be used for the measurement of pressure of a material fluid with strong viscosity.

It is sectional drawing which shows one Example of the pressure measuring apparatus of the fluid in a pipe line of this invention. It is an expanded sectional view of a welding part. It is sectional drawing which shows an inner pipe. The state which fitted the spacer to the inner pipe is shown, (A) is a front view, (B) is a side view. It is sectional drawing which shows the conventional pressure measuring device of the fluid in a pipe line. It is an expanded sectional view of the welding part in FIG.

Explanation of symbols

M Pressure measuring device 1 Outer pipe 11 Flange part 12 Flange part 13 Pressure receiving fluid enclosing part 14 Packing fitting groove 15 Packing fitting groove 2 Inner pipe 20 Inner pipe main body 21 Outward flange part 22 Outward flange part 23 Connection part 24 Connection 3 Spacer 4 Nipple 5 Pressure gauge

Claims (2)

With the thickness and the outer tube of the meat, the flange portion of the thick projecting radially outwardly in the axial direction both ends of the body portion and the body portion of thin-walled, the inner peripheral surface of the outer tube an outer peripheral surface of the flange portion An inner tube disposed on the radially inner side of the outer tube, an annular pressure-receiving fluid sealing portion formed between the outer tube and the main body of the inner tube , and a pressure gauge connected to the pressure-receiving fluid sealing portion In the pressure measuring apparatus for fluid in a pipe line, comprising: a plate member that reduces the substantial internal volume of the pressure-receiving fluid sealing portion on the outer periphery of the main body portion of the inner pipe and protects the inner pipe from a load applied to the inner pipe the cross-sectional shape pressure measuring device in the line fluid, characterized in that it has fitted a spacer formed by winding such that the circular.   The pressure measuring device for fluid in a pipe line according to claim 1, wherein the spacer is made of an aluminum plate.

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