How to repair equipment

Abstract

To provide a repairing method for equipment capable of sufficiently reducing damage due to welding when the inner wall surface is covered with a lining.SOLUTION: There is provided a method for repairing equipment 100 configured to hold a water-containing liquid 60 inside and having an inner wall surface 30 covered with flake lining, the method including a welding step of welding an outer wall surface 20 of the equipment 100 and a welding member 40 in a state where the liquid level of the water-containing liquid 60 inside the equipment 100 is maintained higher than the welding point.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for repairing equipment. [Background technology]

[0002] In some cases, the inner surfaces of various plant equipment are covered with a lining to prevent corrosion. Such linings usually contain a resin component and are made of a material different from the equipment body, which is made of steel or the like. Patent Document 1 proposes a technology for preventing fluid leakage from the butted surface by adjusting the thickness of the lining at the butted surface of two metal pipes with inner linings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3100169 specification Summary of the Invention [Problem to be solved by the invention]

[0004] In equipment whose inner wall surface is covered with a lining, the outer wall surface also gradually deteriorates over time. When corrosion occurs on the outer wall surface due to aging, it is necessary to repair the corroded area. A method of repairing such corroded areas by attaching a resin plate made of FRP resin or the like is considered, but since the durability of the resin plate is low, the frequency of maintenance increases. In addition, if metal fittings are welded to the outer wall surface for repair, there is a concern that the lining provided on the inner wall surface may be damaged by the heat generated by the welding. Therefore, the present disclosure provides a method of repairing equipment that can sufficiently reduce damage caused by welding when the inner wall surface is covered with a lining. [Means for solving the problem]

[0005] The present disclosure provides a method for repairing equipment configured to be capable of holding a water-containing liquid therein and having an inner wall surface covered with a flake lining, the method including a welding step of welding an outer wall surface of the equipment to a welding member while maintaining the liquid level of the water-containing liquid inside the equipment higher than the welding point.

[0006] In the above repair method, when welding the outer wall surface of the equipment whose inner wall surface is covered with a flake lining to the welded member, the liquid level of the water-containing liquid inside the equipment is maintained higher than the welded portion. This suppresses the temperature rise on the back side of the welded portion, i.e., the inner wall surface and the flake lining covering it. This sufficiently reduces damage such as damage and peeling of the flake lining. This repair method can be carried out by maintaining the liquid level of the water-containing liquid inside the equipment higher than the welded portion, so that the work load and cost burden associated with the repair can be sufficiently suppressed. In addition, the above repair method can be applied to equipment in operation.

[0007] The welding heat input during welding in the welding step is preferably 2400 to 5000 J / cm. This makes it possible to sufficiently improve the welding quality between the outer wall surface and the welded member even when welding is performed in one pass, and further suppresses damage to the flake lining caused by heat accompanying welding.

[0008] In the welding process, it is preferable to weld the outer wall surface and the welded member in one pass, which can sufficiently reduce the burden of repair work and shorten the work time to reduce the opportunity loss of equipment.

[0009] The equipment may be a tower or tank. Such equipment is often relatively large and it is difficult to predict where corrosion will occur, but it is easy to maintain the water-containing liquid level higher than the welded part. Therefore, the above-mentioned repair method has a great effect in reducing the burden and cost of repair work. Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a method for repairing equipment that can sufficiently reduce damage caused by welding when the inner wall surface is covered with a lining. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing an example of equipment to be repaired by a method for repairing equipment. [Diagram 2] 1 is a cross-sectional view showing an example of equipment repaired by a method for repairing equipment. [Diagram 3] 1 is a front view showing an example of equipment repaired by a method for repairing equipment. FIG. [Figure 4] 3 is an enlarged cross-sectional view showing a portion of a repaired area repaired by the equipment repair method. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings as needed. However, the following embodiment is an example for explaining the present disclosure, and is not intended to limit the present disclosure to the following content. In the description, the same reference numerals are used for the same elements or elements having the same functions, and redundant descriptions are omitted as needed. Furthermore, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings, unless otherwise specified. Furthermore, the dimensional ratios of each element are not limited to the ratios shown in the drawings.

[0013] A method for repairing an equipment according to one embodiment is a method for repairing an equipment configured to be capable of holding a water-containing liquid inside and having an inner wall surface covered with a flake lining, and includes an introduction step of introducing a water-containing liquid into the equipment, and a welding step of welding an outer wall surface and a welding member. In the welding step, the outer wall surface and the welding member are welded in a state where the liquid level of the water-containing liquid inside the equipment is maintained higher than the welding point.

[0014] The equipment to which the above-mentioned repair method is applied is not particularly limited as long as it is configured to be able to hold a water-containing liquid inside and the inner wall surface is covered with a flake lining. The equipment configured to be able to hold a water-containing liquid inside is not limited to one that retains or stores a liquid during normal operation, but may be one that retains or stores a gas or solid. For example, it may be a tower or tank, or a pipe having a part extending in the vertical direction. The repair method of this embodiment can be used when repairing a corroded part or a thinned part on the outer wall surface of such equipment. The water-containing liquid may be water itself, or may be one that contains trace components other than water, such as seawater and industrial water. It may also be a mixed liquid of water and other components.

[0015] FIG. 1 is a vertical cross-sectional view showing an example of equipment repaired by the above repair method. The tank 100 in FIG. 1 includes a tank body 10 composed of a top plate, a bottom plate, and a side wall. The thickness of the tank body 10 (base material) may be 6 to 30 mm. The inner wall surface 30 of the bottom plate and the side wall of the tank body 10 composed of a normal steel material such as SS material is covered with a flake lining 50. The flake lining 50 may have a laminated structure having a primer layer (adhesive layer) and a flake resin layer containing flakes and resin. The thickness of the flake lining 50 may be 0.2 to 4 mm, or 0.5 to 3 mm. The primer layer is composed of a resin such as a urethane resin or a bis-vinyl ester resin, and is directly bonded to the inner wall surface 30. As the resin, a known resin having an adhesive function can be used.

[0016] The primer layer has a function of bonding the flake resin layer and the inner wall surface 30. The flakes contained in the flake resin layer may be, for example, scaly glass flakes. Examples of the resin contained in the flake resin layer include vinyl ester resins and epoxy resins. Examples of the vinyl ester resin include bis-based vinyl ester resins and novolac-based vinyl ester resins.

[0017] The flake lining 50 has superior heat resistance compared to a resin lining that does not contain flakes. Therefore, it has high resistance to heat generated during welding. Also, flakes tend to have higher thermal conductivity than resin. Therefore, the flake lining 50 can efficiently transfer heat generated during welding from the tank body 10 side to the water-containing liquid 60 side inside. Therefore, for example, peeling of the flake lining 50 from the inner wall surface 30 can be suppressed.

[0018] When repairing the corroded portion 45 on the outer wall surface 20 of the tank body 10 in the tank 100 of FIG. 1, first, an introduction step is performed to introduce a water-containing liquid into the tank 100. For example, when the tank 100 is a tank that stores gas, the water-containing liquid is introduced into the tank 100 from an introduction pipe or introduction hose (not shown). Then, the liquid level of the water-containing liquid in the tank 100 is made higher than the welded portion. When the tank 100 is a tank that stores a liquid different from the water-containing liquid during normal operation, the liquid is drawn out from the tank 100, and the water-containing liquid is introduced to make the liquid level of the water-containing liquid higher than the welded portion. When the tank 100 is a tank into which the water-containing liquid is introduced and retained or stored during normal operation, the water-containing liquid introduced during normal operation may be used as it is. In this way, the introduction step may be performed during normal operation. In either case, the liquid level of the water-containing liquid may be maintained higher than the welded portion during welding.

[0019] Next, a metal weld member 40 is placed on the outer wall surface 20 so as to cover the corroded portion 45. The weld member 40 is a member that is welded to the outer wall surface 20 by welding. Its structure and shape are not particularly limited, and it may be, for example, a plate-shaped member. The material of the weld member 40 is also not particularly limited, and it may be, for example, made of stainless steel material or ordinary steel material such as SS material. The thickness of the weld member 40 may be, for example, 6 mm or more.

[0020] In the welding process, the weld member 40 and the outer wall surface 20 are joined by, for example, fillet welding. This allows the weld member 40 to be firmly joined while sufficiently suppressing damage to the base material (the tank body 10). The welding method may be gas-shielded arc welding, specifically CO2 welding or MAG welding. For example, when the weld member 40 is stainless steel, MAG welding can increase the toughness after welding. The welding may be performed by automatic welding.

[0021] Fig. 2 is a vertical cross-sectional view of a tank 110 obtained by welding a welded member 40 to the outer wall surface 20 of the tank 100 in Fig. 1. Fig. 3 is a front view of the tank 110 shown in Fig. 2. As shown in Figs. 2 and 3, the outer wall surface 20 and the welded member 40 are joined by a fillet portion 42 formed by welding. This fillet portion 42 corresponds to the welded portion in this repair method.

[0022] The upper limit of the welding heat input when welding the welded members 40 is preferably 5000 J / cm, and more preferably 4600 J / cm. This can sufficiently prevent the flake lining 50 from peeling off from the inner wall surface 30 due to heat. The lower limit of the welding heat input when welding is preferably 2400 J / cm, and more preferably 2700 J / cm. This can sufficiently strengthen the weld between the outer wall surface 20 and the welded members 40 even if the welding of the welded members 40 is performed in one pass. The welding heat input is calculated by the following formula (1). Welding heat input [J / cm] = 60 × current [A] × voltage [V] / welding speed [cm / min] (1)

[0023] From the viewpoints of sufficiently strengthening the weld between the outer wall surface 20 and the weld member 40, sufficiently suppressing damage to the flake lining 50, and working efficiency, the current during welding may be, for example, 100 to 150 A. From the same viewpoint, the voltage may be, for example, 20 to 22 V. From the same viewpoint, the welding speed may be, for example, 30 to 70 cm / min.

[0024] During welding of the outer wall surface 20 and the welding member 40, the water level of the water-containing liquid 60 inside the tank 100 is maintained higher than the welding point. This can prevent the temperature of the interface between the inner wall surface 30 and the flake lining 50 and the flake lining 50 from rising too much during welding. Therefore, the occurrence of damage such as peeling and damage of the flake lining 50 can be sufficiently prevented. The temperature of the water-containing liquid 60 inside the tank 100 may be 50°C or less, 40°C or less, or 35°C or less. The maximum temperature of the inner wall surface 30 during welding is preferably 150°C or less, more preferably 140°C or less. This can maintain the adhesive force between the flake lining 50 and the inner wall surface 30 at a sufficiently high level. The maximum temperature of the inner wall surface 30 during welding may be 70°C or more, or 80°C or more.

[0025] From the viewpoint of reducing the burden of repair work and shortening the work time, it is preferable to perform the welding in one pass. In this repair method, the temperature rise of the inner wall surface 30 and the flake lining 50 during welding can be reduced by the water-containing liquid in the tank 100. Therefore, even if welding is performed with a certain degree of increase in welding heat input, damage to the flake lining 50 can be sufficiently suppressed. Therefore, the outer wall surface 20 and the welded member 40 can be welded in one pass while increasing the welding heat input to an extent that does not cause damage to the flake lining 50. This realizes high work efficiency, reduces maintenance costs, and sufficiently reduces opportunity losses associated with maintenance. However, the repair method is not limited to one pass, and welding may be performed in multiple passes depending on the welding leg length, for example.

[0026] After the welding process is completed, the welded portion may be inspected as necessary, and then the tank may be returned to normal operation. For example, the water-containing liquid 60 in the tank 100 may be discharged to the outside, the inside may be dried as necessary, and then the fluid normally stored therein may be introduced. According to the above-mentioned repair method, the damage to the flake lining 50 may be sufficiently reduced, so that the reliability of the tank 110 after repair is improved, and the tank 110 may be used stably for a long period of time. The above-mentioned repair method may be repeated periodically or irregularly.

[0027] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. EXAMPLES

[0028] The present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples.

[0029] (Example) A test tank (width x depth x height = 500 mm x 500 mm x 500 mm) having a rectangular prism-like outer shape was fabricated using steel (SS400, thickness 12 mm). As shown in FIG. 4, a flake lining 50 (thickness: 2 mm, manufactured by Fuji Resin Industrial Co., Ltd.) was applied to the inner wall surface 30 of the side wall of the tank. The flake lining 50 had a four-layer structure consisting of a primer layer (primer #6R, product name), a first flake resin layer (Fuji Flake #6R, product name), a second flake resin layer (Fuji Flake #6H, product name), and a surface resin layer (top coat #6H green, product name). The inner wall surface 30 was covered with the flake lining 50 so that the primer layer of the flake lining 50 was adhered to the inner wall surface 30 of the tank. During bonding, a thermocouple 70 was placed between the flake lining 50 (primer layer) and the inner wall surface 30 (at a position corresponding to the back side of the welded portion) in order to measure the temperature during welding.

[0030] Water was introduced into the tank. The water level was set to be higher than the welding point (the highest point of the point where the fillet portion 42 was formed). Thereafter, as shown in FIG. 4, the welding member 40 was placed at a predetermined position on the outer wall surface 20, and the welding member 40 was welded to the outer wall surface 20 of the tank by automatic welding. A SUS304 plate material (thickness: 9 mm) was used as the welding member 40, and its end was joined to the outer wall surface 20 by welding. The welding conditions for each example were as follows. The fillet portion 42 was formed by welding, and the welding member 40 was joined to the outer wall surface 20. The water temperature in the tank during welding was 16°C.

[0031] <Welding conditions> Welding method: MAG welding, one-pass construction Torch angle: 45° (fillet welding) Welding wire: SF309L (manufactured by Nippon Steel Welding Industry, product name, φ1.2mm) Wire diameter: φ1.2mm

[0032] The welding current, voltage, and welding speed were changed as shown in Table 1, and welding was performed under different welding conditions. Welding was performed under seven different conditions to prepare examples. Table 1 shows the welding heat input (unit: J / cm) for each example calculated using the above formula (1).

[0033] [Table 1]

[0034] The welding heat input in each example was 2496 to 6600 J / cm. In each example, the maximum temperature during welding measured by a thermocouple 70 installed on the back side of the welded portion was as shown in Table 2.

[0035] [Table 2]

[0036] As shown in Table 2, the maximum temperature of the inner wall surface in each example was 92 to 150°C. From these results, it was confirmed that the temperature of the inner wall surface can be lowered by reducing the welding heat input. After welding, visual inspection, hammering inspection, and internal inspection of the flake lining 50 were performed. In the visual inspection, the presence or absence of peeling and discoloration of the flake lining 50 was confirmed. As a result, peeling and discoloration did not occur in any of the examples.

[0037] In the hammering test, the presence or absence of lifting of the flake lining 50 was examined by hammering. As a result, in the example with a welding heat input of 6600 J / cm, some peeling of the flake lining 50 was detected. However, it was not enough to interfere with the use of the tank.

[0038] In the internal inspection, the flake lining 50 was ground with a grinder, and the primer layer was inspected for discoloration and peeling. As a result, no discoloration or peeling occurred in any of the examples. When the fillets of each example were visually inspected, there was no problem with the quality of the weld. Note that when the welding heat input is reduced compared to the above examples, multiple passes of welding may be performed to make the weld sufficiently strong. [Industrial Applicability]

[0039] According to the present disclosure, there is provided a method for repairing equipment in which the inner wall surface is covered with a lining, capable of sufficiently reducing damage caused by welding. [Explanation of symbols]

[0040] 10...tank body, 20...outer wall surface, 30...inner wall surface, 40...welded parts, 42...fillet portion, 45...corroded portion, 50...flake lining, 60...water-containing liquid, 70...thermocouple, 100, 110...tank (equipment).

Claims

1. A method for repairing equipment configured to be capable of holding a water-containing liquid therein and having an inner wall surface covered with a flake lining, comprising the steps of: a welding step of welding an outer wall surface of the equipment to a welding member while maintaining a liquid level of the water-containing liquid inside the equipment higher than a welding point; The method for repairing equipment, wherein the welding heat input during welding in the welding step is 2400 to 5000 J / cm.

2. The method for repairing equipment according to claim 1 , wherein the temperature of the water-containing liquid during welding in the welding step is 50° C. or less.

3. The facility repair method according to claim 1 or 2, wherein the outer wall surface and the weld member are welded in a single pass in the welding step.

4. The facility repair method according to any one of claims 1 to 3, wherein the facility is a tower or tank.

5. A method for repairing equipment described in any one of claims 1 to 4, wherein the temperature of the inner wall surface during welding in the welding process is 150°C or less.

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