JPS60158B2 - Re-explosive crimping method for tube sheets and plugs joined by explosive crimping - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for re-explosive crimping of tube sheets and plugs joined using explosive energy.

It is known in the art to use explosive energy to crimp tubes into tubesheet holes. (Refer to Japanese Patent Publication No. 51-14471, Japanese Patent Publication No. 50-37627, etc.) In this case, if the joined pipe is damaged and becomes unusable,
The tube plate hole in which the unusable tube is connected is plugged with a plug. This method of closing uses a technique similar to the above-described known explosive crimping of tube plate holes and tubes. To explain this using drawings, in Figure 1,
1 is a tube plate, 2 is a tube, 3 is a stopper, and 4 is an explosive crimping layer, and the explosive crimping layer 4 consists of an explosive a, a case b made of plastic or the like, and a detonator c.

Further, 8 is a gap provided between the tube plate 1 and the plug 3. When the detonator c is ignited in this state, the explosive charge a explodes, and its energy presses the position 7 shown in FIG. 2, thereby joining the plug 3 to the tube plate hole. By the way, at this time, defects such as incomplete explosion and cracks may occur.

The purpose of the present invention is to repair tube sheets and plugs when such defects occur, and when plugging a tube hole in a tube sheet by explosive crimping, the plug that has failed in explosive crimping is cut from the tube hole. A tube sheet joined by explosive crimping, characterized in that when removing the plug, the part hardened by explosive crimping of the tube hole is removed, and a re-detonation plug is inserted into the tube hole and re-detonation crimping is performed. and the re-explosion crimping method for plugs.

To explain this in detail with reference to the drawings, when tube sheet 1 and plug 3 are crimped at position 7 by explosive crimping as shown in FIG. Work hardening occurs in the range of 0.3 Yanagi.

Therefore, if a defect such as incomplete explosion or cracking occurs, simply removing the defective plug will make it impossible to explosively press a new plug to the defective part. Therefore, by gradually pressing a cutting blade 6 having a guide rod 5 at the tip against the crimp interface, the plug 3 and the tube plate 1 are
Simultaneously cut about 0.5 side of the pipe hole. After cutting the crimp portion 7, the plug 3 can be removed. The plug 3 is removed, and the re-detonation plug 9 is inserted into the tube hole of the tube sheet 1 after that, as shown in FIG.

This re-detonation stopper 9 has a larger diameter than the stopper 3 so that the gaps 8 are equally spaced as in the case of FIG. With this, the tube sheet 1 and the re-explosion plug 9 can be re-exploded and crimped.
Here, the experimental results are shown in Table 1.

Table 1 shows the length of the crimped part (T in Fig. 2) when the plug 3 and the tube sheet 1 are crimped by the normal explosive crimping shown in Fig. 1, and the length of the crimped part when the crimping is incomplete or fails. The crimping length when the piping is removed and a new plug is reattached and explosion crimped is performed again with the inner surface of the tube hole intact, and the length of the crimped tube when the plug that has failed in crimping is cut and removed from the tube hole along with the plug. The lengths of the crimped parts were measured when the hardened part due to the explosive crimping 2 was removed at the same time, and a re-explosion stopper was attached to the tube hole, followed by explosive crimping.

As shown in Table 1, the length of the three crimped parts in the method of the present invention, in which the failed tube hole hardened part was cut and re-explosive crimping was performed, was approximately the same as that in the normal initial crimping.
When re-explosion crimping is performed without cutting out the hardened portion of the tube hole, the length of the crimped portion is extremely incomplete, indicating that the method of the present invention is extremely effective.

3 Table 1 Length of explosion crimping between plug and tube sheet (Fig. 2, 7) Although this article describes re-explosion crimping of tube sheet and plug, the same applies to repairs when explosive crimping of tube sheet and pipe is performed. Re-explosion crimping is possible.

Next, specific examples will be described. In FIG. 1, the tube plate 1 is made of JISSFHV24 material and has a thickness of 95 mm.
A pipe hole with a diameter of 24 willows is provided in it, and a plug 3 with a tube plate 1 made of the same material, a wall thickness of 2.5 mm, and an outer diameter of 21 legs (however, the closing part side [left side in the figure] is 23.8 legs). Insert the case b made of plastic into the stopper 3, filling it with explosive a (detonation range 6800/sec), detonating it with the detonator c, detonating the explosive a, and causing the explosion as shown in Fig. 2. Pressed into condition.

This is cut at the position of the crimp part 7 with a cutting knife 6 having an outer diameter of 26 ribs, and the plug 3 is removed.After that, as shown in FIG. Insert a re-detonation plug 9 with an outer diameter of 22 ribs (23.8 ribs on the closing part side [on the left side of the figure]), and use the same explosion crimp layer 4 as shown in Figure 1 to re-detonate. In this case, since the outer diameter of the re-explosion stopper 9 is larger than the outside diameter of the stopper 3 by the allowance for cutting the tube hole in the tube sheet 1, the tube sheet 1 and the re-explosion stopper 9 are The gap 8 between the crimped portion layer and the crimped part layer was the same as in the case of Fig. 1, and the crimped state similar to that in Fig. 1 was obtained, and the defective stopper could be made into a proper stopper. The invention is extremely useful especially when applied to heat exchangers in nuclear reactors, which require maintenance and management under strict conditions.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the state when the plug is explosively crimped into the pipe hole, Figure 2 is a sectional view when the defective plug is cut and removed after explosive crimping, and Figure 3 is the state when the plug is re-crimped. FIG. 1...tube plate, 2...tube, 3...stopper, 4
...Explosive crimp layer, 5...Guiding rod, 6...
... Cutting knife, 7 ... Crimping part t 8 ...
...Gap, 9...Re-edge stopper, a...Explosive, b
...Case, c...Detonator. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. When plugging a tube hole in a tube sheet by explosive crimping, when removing the plug that failed in explosive crimping from the tube hole,
A re-explosion of a tube sheet and a plug joined by explosive crimping, characterized by removing the part hardened by explosive crimping of the tube hole along with the plug, and inserting a re-explosion plug into the tube hole and re-exploding crimping. Crimping method.