JPH0235183B2 - KOONYOATSURYOKUNIGASHISEN - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention utilizes homogen technology to directly attach a fuse plug made of a lead-tin alloy to a hole formed in the wall of equipment or piping. This relates to relief plugs.

Although not particularly limited, the present invention is effective, for example, as a pressure relief device in nuclear or thermal power plants, or as a safety device for gas cylinders and the like.

[Conventional technology] In nuclear or thermal power plants, etc. that operate under high temperature and high pressure, if the temperature and pressure rise to a certain limit temperature and pressure in the event of an abnormality, water or steam is released and the structure of equipment, piping, etc. It is necessary to ensure the integrity of things. Therefore, in this type of plant, the "Boiler and Pressure Vessel Safety Regulations" (Japan Boiler Association) requires the installation of a predetermined number of pressure relief valves at predetermined positions of equipment. However, this pressure relief valve is very expensive (currently about 700,000 yen/
), which is extremely disadvantageous economically in large plants where a large number of them must be installed.

On the other hand, there is a safety valve made of a fusible alloy called a "fusible plug" as one of the safety devices that releases the gas inside the container (cylinder) and prevents the abnormal pressure from rising. This fusible plug consists of a substantially cylindrical plug part made of brass, steel, etc. and having a threaded part formed on the outer periphery, and a fusible alloy filled into a hole in the center of the plug part. Then, a washer is attached to the bottom of the shoulder of the container, and the container is screwed into the hole. Gas, etc. will not leak from the fusible plug in the normal operating temperature range, but if the temperature rises to the limit in an abnormal situation, the fusible alloy will melt or flow and open, and gas will be released from there, preventing damage to the container. Ru. The hole formed inside the plug part has a structure with a taper or step that gets wider toward the inside, or a threaded or uneven structure to prevent the fusible alloy from escaping when the internal pressure is below the temperature limit. .

The conventionally used fusible alloys are bismuth,
It is an alloy of lead, tin, cadmium, etc., but generally if it contains more than 55% bismuth, it will solidify and expand, so such an alloy is said to be suitable for fuse plugs.

[Problems to be Solved by the Invention] Although the fuser plug has a simpler structure and is cheaper than a pressure relief valve, it cannot be applied to nuclear power plants, thermal power plants, etc. In conventional fusible plugs, fusible alloys cannot be sufficiently bonded to the plug unless they solidify and expand, so as mentioned above, alloys containing more than 55% bismuth are used.
This is because a fusible plug that can be used in a high temperature atmosphere of 250°C has not yet been developed.

In addition, in the conventional technology, the wall surface of the hole formed in the plug part, that is, the joint part of the fusible alloy, must be threaded, tapered, or stepped, and a thread must be formed on the outer periphery, resulting in a complicated shape and machining. The disadvantage was that the cost was high. Further, in conjunction with this, screws and the like must be similarly formed on the walls of equipment and piping in order to attach the fuser plug, and in this respect as well, the machining is extremely troublesome.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional technology, to be usable even in high-temperature atmospheres of 250°C or higher, and to install the fusible plug by simply drilling a round hole in the wall of the equipment or pipe. An object of the present invention is to provide a high-temperature pressure relief plug that is extremely easy to manufacture and inexpensive.

[Means for Solving the Problems] The present invention, which can achieve the above objects, uses homogen technology to line small-diameter holes formed to penetrate the walls of piping and equipment. This is a pressure relief plug with a structure in which a fuse plug made of a lead-tin alloy is directly attached to it.

Here, the homogen technology is a technology that welds lead, etc. onto the surface of steel, etc. using a gas flame. In the present invention, a lead-tin alloy is melted and filled into a homogen-lined hole.

[Function] By changing the ratio of the lead-tin alloy, the melting temperature can be freely controlled within the range of at least 220 to 280°C. Stainless steel is generally used for the walls of piping and equipment in this type of application, but the homogen technology allows for strong welding of lead, and this homogen lining allows for the use of lead-tin alloys. The fuser plug body is also firmly fixed.

In the normal operating temperature range, water and steam do not leak from the fuser plug, but when an abnormality occurs and the temperature rises to the limit temperature, the fuser plug itself melts or flows and opens, and water and steam are released from the pipe. The soundness of equipment, equipment, etc. is ensured.

[Example] Hereinafter, the present invention will be explained in more detail based on the drawings. FIG. 1 and FIG. 2 are sectional views each showing an embodiment of the pressure relief plug according to the present invention, and are an example of the pressure relief plug being attached to a pipe 10. A hole with a relatively small diameter (for example, about 12 mmφ) is drilled through the wall of the pipe 10, a homogen lining 12 is formed on the wall of the hole, and a fusible plug made of a lead-tin alloy is installed inside the homogen lining 12. 14 is formed. Here, the homogen lining 12 is a welded coating made of lead or the like, and functions to join the stainless steel pipe 10 and the fusible plug portion 14. The hole formed in the pipe 10 may be a simple round hole. Therefore, processing can be performed extremely easily. The composition ratio of the lead-tin alloy constituting the fuse plug portion 14 is adjusted to have a predetermined melting temperature by changing the blending ratio of the lead-tin alloy according to the set temperature of the pressure relief operation.

FIG. 3 shows a graph showing the relationship between the tin content and the melting temperature. The proportion of tin with a melting point of 232℃ in lead with a melting point of 327℃ is increased from 19.5% to 56%.
The temperature at which the fuser plug body 14 melts was determined by flowing high-temperature water through a stainless steel pipe equipped with the fuser plug body by fabricating five types of fuser plug bodies with varying values between % and 14. be. Since the melting temperature changes almost linearly in the range of 220 to 280℃ with respect to the tin content, determining the pressure relief operating temperature will uniquely eliminate lead,
The content of tin in the tin alloy can be determined. Therefore, using such an alloy, it is possible to open the pressure relief plug at a predetermined temperature.

To actually manufacture such a pressure relief plug,
For example, do it in the following order: First, a hole of a predetermined size is drilled at a predetermined position in the pipe or container wall using a drill or drilling machine. Next, the rust, oil, etc. adhering to the cutting surface are removed by pickling. Then, a flux containing zinc chloride as a main component is applied to the cut surface, and hydrogen and
Create a reducing atmosphere at 250-300°C in the hole using an oxygen burner, etc., and coat the cut surface with a lead-tin alloy while melting the flux. The coating thickness obtained by this homogenization process is approximately 1 to 2 mm. The hole where the coating was formed is again placed in a reducing atmosphere at 250 to 300℃, and lead and
While melting the tin alloy, the alloy is injected into the hole while placing a backing on the hole to prevent the molten metal from flowing out. Then, slowly cool it in the air. By such a method, the pressure relief plug according to the present invention can be easily manufactured.

[Effects of the Invention] As described above, the present invention utilizes homogen technology to directly form a fuse plug body made of a lead-tin alloy in a hole drilled in a wall of a pipe or device. Furthermore, it can be used even under high-temperature conditions such as 250°C or higher, and the shape is extremely simple and processing is easy, as the fuse plug installation part only requires drilling a round hole with a drill, etc. The structure of the fusible plug is simple, and even when the fusible plug is melted and poured, the work is very simple, and it has an extremely excellent effect in that the pressure relief plug can be manufactured at a very low cost. . Incidentally, the pressure relief plug according to the present invention can be manufactured for about 50,000 yen per piece at present.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views showing an embodiment of the pressure relief plug according to the present invention, and FIG.
1 is a graph showing the relationship between tin content and melting temperature in a tin alloy. 10... Stainless steel piping, 1... Homogen lining, 14... Fuse plug part.

Claims (1)

[Claims] 1. A high-temperature pressure relief plug characterized in that a fuse plug made of a lead-tin alloy is directly attached to a hole drilled in the wall of piping or equipment via a homogen lining.