JPH01275993A - Piping system having branch pipe with closed tip - Google Patents

Abstract

PURPOSE:To prevent a whirling flow in a main flow pipeline from penetrating into a preceding closed branch pipe by setting up a whirling flow preventive means, serving as resistant against the whirling flow, in a branch pipe inlet part or a joint with the main flow pipeline. CONSTITUTION:A whirling flow preventive means 6 is set up in a branch pipe inlet part or a joint of a branch pipeline 2 with a main flow pipeline 1. Therefore a whirling flow in this branch pipe 2 is preventable, and thereby any fluid in the main flow pipeline 1 can be prevented from penetrating into the branch pipe. Consequently, a temperature rise and a temperature variation in the branch pipe 2 can be kept back and, what is more, repetitive thermal stress and stress corrosion cracking in the branch pipe 2 are thus preventable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a piping system having a branch pipe with a closed tip, and in particular, to prevent a swirling flow in a mainstream piping from entering into a branch pipe with a closed tip. Relating to a piping system designed to prevent

[Conventional technology]

For example, as shown in Figure 2, in a piping system where a branch pipe with a closed tip is connected to the mainstream pipe by a valve or detector, if there is a swirling flow in the mainstream pipe, this swirling flow will branch out. The phenomenon of penetrating into pipes was elucidated for the first time through visualization experiments. If high temperature water is flowing in the main pipe,
When this phenomenon occurs, the low-density high-temperature water swirls and enters the high-density low-temperature water in the branch pipe, which is cooled by heat radiation, so the low-temperature water and high-temperature water alternately swirl and flow in the branch pipe, causing the branch pipe to flow. This causes temperature fluctuations within the pipe.

In addition, it is generally well known that swirling flow occurs in the wake of valves and elbows in mainstream piping, and branch pipes with closed ends are not used as detection piping or during regular operation. There are many piping systems in various plants that are used only in emergencies.

However, since it is not known that the swirling flow in the main flow pipe enters the branch pipe described above, the branch pipe with a closed end is generally designed as a low-temperature pipe.

For this reason, in a branch pipe with a closed tip, the swirling flow of high-temperature water in the mainstream pipe enters, causing temperature rise and temperature fluctuation in the branch pipe, and piping design that takes into account repetitive thermal stress, especially atomic In a couplant, it is necessary to design piping that takes stress corrosion cracking into consideration, or to prevent the swirling flow in the mainstream piping from entering the branch pipe.

Note that Japanese Patent Application Laid-Open No. 61-38594 may be cited as a related publication.

[Problem to be solved by the invention]

In the above conventional technology, the phenomenon that high-temperature water in the mainstream pipe enters a branch pipe with a closed tip due to swirling flow was not known, so in the branch pipe design, it is treated as a low-temperature pipe, and as a result of high-temperature water entering. No consideration was given to temperature rises and temperature fluctuations, and there were problems with repetitive thermal stress in piping and stress corrosion cracking in the atomic couplant.

SUMMARY OF THE INVENTION An object of the present invention is to provide a piping system of this type in which the swirling flow in the main piping does not enter the closed branch pipe.

[Means to solve the problem]

The above object is achieved by installing a swirl flow prevention means that resists swirl flow at the inlet of the branch pipe, which is the junction with the main flow pipe.

[Effect]

The reason why the swirling flow in the mainstream piping enters the closed branch pipe is that part of the swirling component of the flow in the mainstream piping enters, so the branch pipe inlet is designed to provide resistance to the flow of this swirling component. If a swirl flow prevention means is installed in the branch pipe, swirl flow can be prevented in the branch pipe, and fluid in the main flow pipe can be prevented from entering the branch pipe. This can prevent temperature increases and temperature fluctuations within the branch pipe, and can prevent repeated thermal stress and stress corrosion cracking of the branch pipe.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows a swirl flow prevention means 6 installed at the inlet of the branch pipe, which is the joint between the main plumber and the branch pipe 2, and FIGS. 3 to 5 show the specific structure of the swirl flow prevention means 6. It is something that That is, in FIG. 3, a cross plate swirling flow prevention means 7 is installed in the branch pipe 2 at the inlet of the branch pipe to prevent swirling flow in the branch pipe, and the fluid in the main flow pipe 1 flows into the branch pipe 2. This is to prevent Figure 4 shows branch pipe 2 at the branch pipe inlet.
A vertical plate swirling flow prevention means 8 is installed inside the branch pipe 2 to prevent swirling flow, and as shown in FIG. 5, a horizontal plate swirling flow prevention means 9 is installed inside the branch pipe 2 at the branch pipe entrance to prevent swirling flow. It is something.

Fig. 6 shows a case in which a swirl flow prevention device 1) and plate 1o are installed as swirl flow prevention means at the inlet of the branch pipe, which is the junction between the main flow pipe 1 and the branch pipe 2, and Figs. Flow prevention plate 10
This shows the specific structure of . That is, FIG. 7 shows an orifice-type swirl flow prevention plate 11 that prevents the swirl flow 4 in the mainstream piping 1 from entering the branch pipe 2, and FIG. This prevents the swirling flow inside the branch pipe 2 from entering the branch pipe 2.

In FIG. 9, a throttle pipe 13 is provided in the branch pipe at the joint between the main flow pipe 1 and the branch pipe 2 to prevent the swirling flow 4 in the main flow pipe 1 from entering the branch pipe 2.

FIG. 10 shows that the swirling flow prevention means 14 shown in FIGS. This is to prevent

〔Effect of the invention〕

According to the present invention, it is possible to prevent the swirling flow in the mainstream piping from entering the branch pipe with a closed end, so even when the fluid in the mainstream piping is high-temperature water, temperature rise and temperature fluctuation in the branch pipe can be prevented. , can prevent repeated thermal stress and stress corrosion cracking of branch pipes.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view showing the main parts of the piping system of the present invention;
FIG. 2 is a side view of the piping system, and FIGS. 3 and 4, which illustrate the phenomenon that the swirling flow in the mainstream piping enters a branch pipe with a closed tip, as revealed by visualization experiments. FIG. 5 is a diagram for explaining the structure of the swirl flow prevention means, FIG. 6 is a diagram for explaining the mounting position of the swirl flow prevention plate according to the present invention, and FIGS. 7 and 8 are diagrams for explaining the swirl flow prevention plate. FIG. 9 is a diagram for explaining the branch pipe throttle piping according to the present invention, and FIG. 10 is a diagram for explaining the swirl flow prevention mechanism according to the present invention installed in the main flow piping. . 1... Mainstream piping, 2... Branch pipe with closed tip, 3.
... Closed valve, 4... Swirling flow in the main stream pipe, 5... Swirling flow in the branch pipe, 6... Swirling flow prevention mechanism, 7... Cross plate swirling flow prevention mechanism, 8... Vertical Plate swirl flow prevention mechanism, 9
...Horizontal plate swirl flow prevention mechanism, 10...Swirl flow prevention plate, 11...Orifice type swirl flow prevention plate, 12...Multi-hole swirl flow prevention plate 1. Sword 3 Figure 4. Mouth No. S Concave 6th mouth Gyuyu 7th 8th mouth <ct) <b) (α) (b) 9th
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Claims (1)

[Claims] 1. In a piping system having a mainstream piping and a branch pipe with a closed end connected in the middle of the mainstream piping, inside the branch pipe near the joint between the mainstream piping and the branch pipe. A piping system having a branch pipe with a closed tip, characterized in that a swirl flow prevention means is provided to prevent the swirl flow in the main flow pipe from entering the branch pipe. 2. A piping system having, as the swirling flow prevention means according to claim 1, a branch pipe with a closed end formed of a plate having a cross-shaped or linear cross-sectional shape. 3. In a piping system consisting of a mainstream piping through which a high-temperature medium flows and a branch pipe with a closed end connected in the middle of this mainstream piping, a branch pipe with a diameter of A closed tip characterized in that a swirl flow prevention plate having a smaller diameter and a plurality of holes is provided to prevent the high temperature medium in the main flow pipe from entering the branch pipe due to the swirl flow. Piping system with branch pipes. 4. In a piping system consisting of a branch pipe with a closed end connected to the mainstream piping, the branch pipe section at the joint between the mainstream piping and the branch pipe is made thinner, and the branch pipe itself is used as a throttling mechanism to prevent rotation within the mainstream piping. A piping system having a branch pipe with a closed end, characterized in that it prevents flow from entering the branch pipe. 5. In a piping system consisting of a main flow pipe through which liquid or gas flows and a branch pipe with a closed end connected to the main flow pipe, the pipe on the upstream side of the joint between the main flow pipe and the branch pipe 1. A piping system having a branch pipe with a closed tip, characterized in that a swirl flow prevention mechanism is installed in the main flow piping to prevent swirl flow at the joint portion. 6. A piping system consisting of a branch pipe with a closed end connected to a mainstream piping, characterized in that the branch pipe with a closed end is provided with measures against stress corrosion cracking.