JPS60211289A - Repair of tube - Google Patents

Abstract

PURPOSE:To efficiently repair a heat transfer tube with high reliability by a method wherein the expanded state and damaged position of the heat transfer tube are detected and one of a plurality of repairing methods is selected based upon the detected expanded state and damaged position so as to tightly fix the upper end part and lower end part of a sleeve to the heat transfer tube. CONSTITUTION:In case of a heat transfer tube, which is partially expanded by rollers, grooves 10 are cut in the lower end part 8 of the tube, which is expanded by rollers, so as to be bitten into by a smooth sleeve 6 by expanding. In addition, the heat transfer tube 3 is bitten into by projections 9 provided on the outer surface of the sleeve 6 at the upper end part 7 hydraulically expanded. When the damaged portion locates at the prearranged position for cutting groove at the lower end part, the repair with a sleeve is done by applying seal- welding at the tip of the lower end part 8 of the sleeve and by sealing the non- expanded part and hydraulically expanded part with the protruding sleeve.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for repairing heat exchanger tubes such as steam generators and heat exchangers.

Generally, in a heat exchanger 1 as shown in FIG. 3, a tube sheet 2 and a heat exchanger tube 3 are assembled so as to be in close contact with each other. The general method for assembly is to expand the heat transfer tubes. As shown in FIG. 4, this tube expansion method involves expanding the heat exchanger tubes 3 in the tube sheet 2 by O-9 by a partial length equal to the tube sheet thickness during manufacture (referred to as partial tube expansion), and as shown in FIG. , There are tubes expanded by rollers over the entire thickness of the tube plate (referred to as full-thickness tube expansion). In addition, in a partially expanded heat exchanger, the tube sheet 2 and the heat exchanger tubes 30
In order to avoid chemical concentration of liquid in the gap (clevis) 4 formed between the tubes, some tubes are re-expanded over the entire thickness of the tube sheet (re-roll) using hydraulic pressure tube expansion. There is a sleeve repair method shown in FIG. 6 as a countermeasure for when damage 5 occurs in the heat tube 3 and the fluid inside the tube passes through the wall thickness of the tube and leaks to the outside (or in the opposite direction). In the sleeve repair method, a sleeve 6 is inserted into the heat exchanger tube 3 with damage 5,
Upper end 7 and lower end 8 of sleeve 6 with damage 5 in between
The heat exchanger tube 3 and sleeve 6 are tightly fixed at the part shown in FIG.
This is to ensure confidentiality. Upper end 7 or lower end 8
In order to obtain airtightness, if the heat exchanger tube is an unexpanded section or a hydraulically expanded section, as shown in Fig. 7, an annular projection 9 is provided on the outer surface of the sleeve, and this is inserted into the heat exchanger tube. If the heat exchanger tube is work hardened by roller expansion, a groove 10 is cut into the heat exchanger tube as shown in Fig. 8, and a smooth sleeve 6 is expanded to fit the groove. (There is a method to obtain airtightness by inserting the sleeve. Also, seal welding 11 may be done at the lower end of the tube plate as shown in Figure 9. Elemental technologies have not been combined, and depending on the area of damage, it may not be possible to repair the sleeve.

The purpose of the present invention is to improve a sleeve repair method for damage to a heat exchanger tube due to heat exchanger tubes.
After detecting the damage position and cutting the protrusions of the sleeve with annular protrusions into the inside of the heat exchanger tube on the upper and lower ends of the sleeve separately, or by cutting grooves on the inner surface of the heat exchanger tube. The present invention provides a method for repairing a tube, which is characterized in that the pipe is tightly fixed to a heat exchanger tube by either expanding a smooth sleeve or rail welding the end of the heat exchanger tube and the end of the sleeve.

Examples will be shown and explained in detail below.

Fig. 1 shows an example of application to a tube partially expanded by roller expansion.In the lower end portion 8 of the roller expanded tube, a groove is formed in the heat transfer tube 3, and a smooth sleeve 6 is formed into a groove 10 by expanding the tube. A protrusion 9 is provided on the outer surface of the sleeve 6 at the upper end portion 7 which has been hydraulically expanded (or the upper end portion 7 which has not been expanded) and is inserted into the heat transfer tube 3.

FIG. 2 shows an example of a method for machining grooves 10 in the heat exchanger tube 3, in which the damaged area is at or below the groove machining position of the lower end 8. Since groove machining cannot be applied, the lower end of the sleeve By performing seal welding 11 on the tip of portion 8, efficient sleeve repair is performed.

That is, in the method of the present invention, as a sealing method in the sleeve repair method for repairing damage to tube sheet autothermal tubes, the unexpanded portions and hydraulically expanded portions of heat transfer tubes are sealed with a sleeve with protrusions shown in Fig. 7, and roller expansion is performed. For the sealing method shown in Figure 8, a groove is machined in the heat exchanger tube and a smooth sleeve is inserted into the groove by expanding the tube.Also, as a sealing method for the lower end of the tube plate, the seal welding shown in Figure 9 is also applied to the damaged position. These elemental technologies are optimally combined depending on the expanded state of the heat transfer tube and the damage position detected in advance.

Therefore, the method of the present invention is applicable to damage in all parts of the tube sheet autothermal tube, and enables time-efficient and highly reliable repair.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing one embodiment of the method of the present invention, Figure 2 is an explanatory diagram showing another embodiment of the method of the present invention, Figure 3 is a schematic diagram of an example of an apparatus for carrying out the method of the present invention, and Figure 4 is an explanatory diagram showing one embodiment of the method of the present invention. or 5
The figure is an explanatory diagram of the state of the heat exchanger tube with the inner region of the tube sheet and the damaged state. Figure 6 is a schematic diagram of the sleeve repair part of the tube sheet autobiographical heat tube. Figures 7 to 9 are the close fixation parts of the sleeve using conventional element technology. Explanatory diagram. 2: Tube sheet, 3: Heat exchanger tube, 5: Damage, 6: Sleeve, 9:
Projection, 10: Groove, 11: Seal weld port 4 V5 6 Note 8 Nnnq1 Figure 7 Closed q

Claims (1)

[Claims] In a sleeve repair method for damage in the tube plate of a heat exchanger tube, the expanded state of the heat exchanger tube and the damaged position are detected, and based on the conditions, the upper end and lower end of the sleeve are individually repaired with a protrusion of the sleeve with an annular protrusion. into the heat exchanger tube, by grooving the inner surface of the heat exchanger tube and then expanding a smooth sleeve, or by seal-welding the ends of the heat exchanger tube and sleeve. A pipe repair method characterized by closely fixing the pipe.