Welding rod and welding method for penstock stiffening ring welding

Abstract

The invention discloses a welding rod for welding a stiffening ring of a pressure steel pipe, which is composed of a coating and a welding core. The coating includes, by weight percentage, 20-35% titanium dioxide, 12-26% wollastonite, 10-14% kaolinite, 8-14% siderite, 2-9% solid water glass, 3-7% electrolytic manganese, 2-6% diopside, 1-5% aluminum oxide, 0.2-0.7% magnesium oxide, 0.2-0.5% carboxymethyl cellulose, and 0.1-0.3% metal nickel, and the total amount of each component is 100%. The invention also discloses a method for welding a stiffening ring of a pressure steel pipe using the welding rod. The welding rod for welding a stiffening ring of a pressure steel pipe of the invention will not expand and explode under high temperature of arc welding, and the arc is stable during welding with the welding rod, the spatter is small, and the welding performance is good. The method for welding a stiffening ring of a pressure steel pipe using the welding rod is simple to operate, and the preload borne by the steel pipe is increased after welding.

Description

Technical Field

[0001] The invention relates to the technical field of welding stiffening rings for penstocks, and in particular to a welding rod and a welding method for welding stiffening rings for penstocks. Background Art

[0002] Penstocks are made of low-alloy structural steel, which has good pressure resistance and excellent welding performance. They are widely used in projects with high pressure requirements. In order to improve the external pressure resistance of penstocks, stiffening rings are usually set on the pipe wall. The stiffening rings and steel pipes are mainly connected by welding. In the construction of penstock stiffening rings, the most critical process is welding. In water conservancy projects, the commonly used welding methods for penstocks and stiffening rings are arc automatic welding, manual arc welding, carbon dioxide gas shielded welding, etc.

[0003] The welding rod commonly used for welding stiffening rings of pressure steel pipes is alkaline welding rod. However, alkaline welding rod is easily affected by moisture if not properly stored. When welding in a humid environment, the damp welding rod will contain a large amount of water. Under the high temperature of the arc, it will expand and burst, causing metal droplets to splash everywhere, thus affecting the welding operation and post-weld performance. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] Another object of the present invention is to provide a welding rod for welding stiffening rings of pressure steel pipes, which will not expand and explode under high temperatures of arc welding. During welding, the arc is stable, spatter is small, and welding performance is good. By adding a certain amount of rare earth metals to the welding core, the impact toughness of the weld is further guaranteed.

[0006] In order to achieve these purposes and other advantages according to the present invention, the technical solution of the present invention is as follows:

[0007] A welding rod for welding a stiffening ring of a pressure steel pipe consists of a coating and a welding core. The coating comprises, by weight percentage, 20-35% titanium dioxide, 12-26% wollastonite, 10-14% kaolinite, 8-14% siderite, 2-9% solid water glass, 3-7% electrolytic manganese, 2-6% diopside, 1-5% aluminum oxide, 0.2-0.7% magnesium oxide, 0.2-0.5% carboxymethyl cellulose, and 0.1-0.3% metallic nickel, and the total amount of each component is 100%.

[0008] Preferably, the coating comprises, by weight percentage, 24-32% titanium dioxide, 15-23% wollastonite, 11-13% kaolinite, 10-12% siderite, 4-7% solid water glass, 4-6% electrolytic manganese, 3-5% diopside, 2-4% aluminum oxide, 0.4-0.6% magnesium oxide, 0.2-0.4% carboxymethyl cellulose, and 0.2-0.3% metallic nickel, and the total amount of each component is 100%.

[0009] Preferably, the coating comprises, by weight percentage, 28.7% titanium dioxide, 23% wollastonite, 13% kaolinite, 12% siderite, 7% solid water glass, 6% electrolytic manganese, 5% diopside, 4% aluminum oxide, 0.6% magnesium oxide, 0.4% carboxymethyl cellulose, and 0.3% metallic nickel.

[0010] Preferably, the welding core comprises, by weight percentage: C≤0.03%, Si≤0.25%, Mn≤1.68%, S≤0.018%, P≤0.02%, Ni≤0.001%, Cr≤3.5%, Mo≤0.15%, Cu≤0.16%, Nd≤0.001%, and the balance is Fe.

[0011] Preferably, the mass ratio of the coating to the welding core is 2:8.

[0012] Preferably, the main component of titanium dioxide is TiO2, wherein TiO2≥98%, S≤0.01%, P≤0.01%; the particle size specification is 100% passing 50 mesh, more than 85% passing 80 mesh, and no more than 40% passing 140 mesh.

[0013] Preferably, the iron carbonate content of the siderite is at least 60%.

[0014] Preferably, the solid water glass is sodium silicate powder with a modulus of 3.2.

[0015] The object of the present invention can be further achieved by a welding method for a pressure steel pipe stiffening ring, wherein the method comprises the following steps:

[0016] Step 1: Use the above-mentioned welding rod to weld multiple stiffening ring petals to the outside of the pressure steel pipe by arc welding according to the principle of symmetrical parallel welding to form a stiffening ring, wherein the stiffening ring and the steel pipe wall are welded to form a combined weld of a double-sided fillet weld, and the groove type is an I-type groove; the butt surfaces between the multiple stiffening ring petals are welded by gas welding;

[0017] Step 2: In the plane formed by the steel pipe and the stiffening ring, the welding rod is used to weld the stiffening ribs by high-frequency welding for reinforcement, and the size of the stiffening ribs is 300 mm×40 mm×10 mm;

[0018] Among them, the gas welding is oxyacetylene welding, the surface is sandblasted before spray welding, and the surface is preheated to 265℃ before spray welding remelting.

[0019] Preferably, in step 2, the frequency of high frequency welding is 350-400 kHz, and the welding speed is 20-25 m / min.

[0020] The present invention has at least the following beneficial effects:

[0021] 1. The welding rod for welding the stiffening ring of the pressure steel pipe of the present invention optimizes the composition and content of the coating and the welding core to obtain a welding rod with excellent mechanical properties and no expansion and explosion phenomenon under high temperature of arc welding. The arc is stable, the spatter is small, and the welding performance is good during the welding process of the welding rod. A certain amount of rare earth metal is added to the welding core to further ensure the impact toughness of the weld.

[0022] 2. The method for welding the stiffening ring of a pressure steel pipe using the welding rod for welding the stiffening ring of a pressure steel pipe of the present invention is simple to operate and increases the preload borne by the steel pipe after welding. DETAILED DESCRIPTION

[0023] The present invention is described in further detail below so that those skilled in the art can implement it according to the description.

[0024] It should be noted that the testing methods in the following embodiments are conventional methods unless otherwise specified, and the materials can be obtained from commercial channels unless otherwise specified.

[0025] It should be noted that, in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating directions or positional relationships, are based on the directions or positional relationships shown and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0026] Titanium dioxide: In welding, its main function is to form slag and stabilize the arc. On the one hand, it generates active slag; on the other hand, it can stabilize the arc, reduce spatter, keep the molten zone safe and stable, and refine the weld ripples. In addition, in the process of electrode preparation, titanium dioxide can improve the plasticity and viscosity of the coating and reduce the difficulty of pressure coating. However, when the amount of titanium dioxide is too much, the mechanical properties of the weld will be reduced, the probability of cracks will increase, and it will be easy to break during cold bending.

[0027] Wollastonite: In welding, it can accelerate the melting rate and improve the fluidity of the slag. As a welding rod coating, it has the advantages of energy saving, anti-pore, enhanced weld strength, smooth weld surface, improved droplet transition, and accelerated coating melting rate.

[0028] Kaolinite: In welding, it has low temperature, narrow melting range, strong fluidity, good permeability, and enhances weld strength.

[0029] Siderite: Enhances weld strength and improves the moisture resistance of welding rods.

[0030] Solid water glass: During the welding process, it stabilizes the arc, forms slag, improves the adhesion of the coating, and ensures that the coating covers the surface of the welding core. If the content is too much, there will be serious spattering during welding, the viscosity of the slag will increase, and the mechanical properties of the weld will be affected.

[0031] Alumina, magnesium oxide, electrolytic manganese, and metallic nickel: adjust the alloy composition in the weld, improve the weld structure, and ensure the mechanical properties of the weld.

[0032] Diopside: During welding, it improves the pressure-coating performance of the electrode, improves the smoothness of the weld surface, reduces weld peeling, improves the low-temperature impact toughness of the deposited metal, and improves the mechanical properties of the deposited metal.

[0033] Carboxymethyl cellulose: During the welding process, it can improve the pressure coating performance of the electrode and improve the smoothness of the weld surface after welding. Its thermal decomposition property can improve the arc blowing force and arc starting performance.

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the following embodiments are provided for illustration:

[0035] <Example 1>

[0036] A welding rod for welding a stiffening ring of a pressure steel pipe. The coating comprises, by weight percentage, 28.7% titanium dioxide, 23% wollastonite, 13% kaolinite, 12% siderite, 7% solid water glass, 6% electrolytic manganese, 5% diopside, 4% aluminum oxide, 0.6% magnesium oxide, 0.4% carboxymethyl cellulose, and 0.3% metallic nickel.

[0037] In terms of weight percentage, the welding core includes: C: 0.012%, Si: 0.18%, Mn: 1.20%, S: 0.005%, P: 0.007%, Ni: 0.001%, Cr: 2.5%, Mo: 0.09%, Cu: 0.10%, Nd: 0.001%, and the balance is Fe.

[0038] The content of iron carbonate in the siderite is 60%, the main component of titanium dioxide is TiO2, wherein TiO2≥98%, S≤0.01%, P≤0.01%; the particle size specification is 100% passing 50 mesh, more than 85% passing 80 mesh, and no more than 40% passing 140 mesh; the mass ratio of the coating to the welding core is 2:8. The solid water glass is a sodium silicate powder with a modulus of 3.2.

[0039] The preparation method of the welding rod for welding the steel pipe stiffening ring is as follows: after mixing the coating according to the proportion of each component and stirring evenly, adding 11% of the weight of the coating as a binder (the binder is potassium sodium water glass, the potassium sodium ratio is 1:1, and the Baume concentration is 38.0-41.0Be') and stirring evenly to prepare a coating paste, the mass ratio of the coating to the welding core is 2:8, and then sending it into a battening machine to wrap it on the welding core, and then drying it at 95°C (first drying) and 380°C (second drying) to prepare the welding rod for welding the steel pipe stiffening ring, the welding rod welding core diameter is 3.5mm, and the outer diameter of the finished welding rod after drying is 4.8mm.

[0040] The method for welding a pressure steel pipe stiffening ring by using the welding rod for welding a steel pipe stiffening ring comprises the following steps:

[0041] Step 1: using the welding rod to weld multiple stiffening ring petals to the outside of the pressure steel pipe by arc welding according to the principle of symmetrical parallel welding to form a stiffening ring, wherein the stiffening ring is welded to the steel pipe wall to form a combined weld of a double-sided fillet weld, and the groove type is an I-type groove; the butt surfaces between the multiple stiffening ring petals are welded by gas welding;

[0042] Step 2: In the plane formed by the steel pipe and the stiffening ring, the welding rod is used to weld the stiffening ribs by high-frequency welding for reinforcement, and the size of the stiffening ribs is 300 mm×40 mm×10 mm; wherein the frequency of the high-frequency welding is 400 kHZ, and the welding speed is 25 m / min;

[0043] Among them, the welding current of arc welding is 300A, the welding voltage is 30V, and the no-load voltage is 60V; the gas welding is oxyacetylene welding, the surface is sandblasted before spray welding, and preheated at 265°C, and then sprayed and remelted after preheating. The remelting temperature is 750°C and the remelting holding time is 6s.

[0044] <Example 2>

[0045] A welding rod for welding a stiffening ring of a pressure steel pipe. The coating comprises, by weight percentage, 20% titanium dioxide, 26% wollastonite, 14% kaolinite, 14% siderite, 9% solid water glass, 7% electrolytic manganese, 6% diopside, 3% aluminum oxide, 0.6% magnesium oxide, 0.2% carboxymethyl cellulose and 0.2% metallic nickel.

[0046] In terms of weight percentage, the welding core includes: C: 0.015%, Si: 0.13%, Mn: 0.60%, S: 0.012%, P: 0.012%, Ni: 0.0008%, Cr: 1.6%, Mo: 0.07%, Cu: 0.16%, Nd: 0.0006%, and the balance is Fe.

[0047] The content of iron carbonate in the siderite is 60%, the main component of titanium dioxide is TiO2, wherein TiO2≥98%, S≤0.01%, P≤0.01%; the particle size specification is 100% passing 50 mesh, more than 85% passing 80 mesh, and no more than 40% passing 140 mesh; the mass ratio of the coating to the welding core is 2:8. The solid water glass is a sodium silicate powder with a modulus of 3.2.

[0048] The preparation method of the welding rod for welding the steel pipe stiffening ring is as follows: after mixing the coating according to the proportion of each component and stirring evenly, adding 9% of the weight of the coating as a binder (the binder is potassium sodium water glass, the potassium sodium ratio is 1:1, and the Baume concentration is 38.0-41.0Be') and stirring evenly to prepare a coating paste, the mass ratio of the coating to the welding core is 2:8, and then sending it into a battening machine to wrap it on the welding core, and then drying it at 100°C low temperature (first drying) and 380°C high temperature (second drying) to prepare the welding rod for welding the steel pipe stiffening ring, the welding rod welding core diameter is 3.5mm, and the outer diameter of the finished welding rod after drying is 4.8mm.

[0049] The method for welding a pressure steel pipe stiffening ring by using the welding rod for welding a steel pipe stiffening ring comprises the following steps:

[0050] Step 1: using the welding rod to weld multiple stiffening ring petals to the outside of the pressure steel pipe by arc welding according to the principle of symmetrical parallel welding to form a stiffening ring, wherein the stiffening ring is welded to the steel pipe wall to form a combined weld of a double-sided fillet weld, and the groove type is an I-type groove; the butt surfaces between the multiple stiffening ring petals are welded by gas welding;

[0051] Step 2: In the plane formed by the steel pipe and the stiffening ring, the welding rod is used to weld the stiffening ribs by high-frequency welding for reinforcement, and the size of the stiffening ribs is 300 mm×40 mm×10 mm; wherein the frequency of the high-frequency welding is 400 kHZ, and the welding speed is 25 m / min;

[0052] Among them, the welding current of arc welding is 300A, the welding voltage is 30V, and the no-load voltage is 60V; the gas welding is oxyacetylene welding, the surface is sandblasted before spray welding, and preheated at 265°C, and then sprayed and remelted after preheating. The remelting temperature is 750°C and the remelting holding time is 6s.

[0053] <Example 3>

[0054] A welding rod for welding a stiffening ring of a pressure steel pipe. The coating comprises, by weight percentage, 35% titanium dioxide, 18% wollastonite, 14% kaolinite, 14% siderite, 5% solid water glass, 5% electrolytic manganese, 4% diopside, 4% aluminum oxide, 0.7% magnesium oxide, 0.2% carboxymethyl cellulose, and 0.1% metallic nickel.

[0055] In terms of weight percentage, the welding core includes: C: 0.013%, Si: 0.21%, Mn: 1.36%, S: 0.009%, P: 0.018%, Ni: 0.001%, Cr: 0.8%, Mo: 0.14%, Cu: 0.09%, Nd: 0.0009%, and the balance is Fe.

[0056] The content of iron carbonate in the siderite is 60%, the main component of titanium dioxide is TiO2, wherein TiO2≥98%, S≤0.01%, P≤0.01%; the particle size specification is 100% passing 50 mesh, more than 85% passing 80 mesh, and no more than 40% passing 140 mesh; the mass ratio of the coating to the welding core is 2:8. The solid water glass is a sodium silicate powder with a modulus of 3.2.

[0057] The preparation method of the welding rod for welding the steel pipe stiffening ring is as follows: after mixing the coating according to the proportion of each component and stirring evenly, adding 11% of the weight of the coating as a binder (the binder is potassium sodium water glass, the potassium sodium ratio is 1:1, and the Baume concentration is 38.0-41.0Be') and stirring evenly to prepare a coating paste, the mass ratio of the coating to the welding core is 2:8, and then sending it into a battening machine to wrap it on the welding core, and then drying it at 90°C (first drying) and 380°C (second drying) to prepare the welding rod for welding the steel pipe stiffening ring, the welding rod welding core diameter is 3.5mm, and the outer diameter of the finished welding rod after drying is 4.8mm.

[0058] The method for welding a pressure steel pipe stiffening ring by using the welding rod for welding a steel pipe stiffening ring comprises the following steps:

[0059] Step 1: using the welding rod to weld multiple stiffening ring petals to the outside of the pressure steel pipe by arc welding according to the principle of symmetrical parallel welding to form a stiffening ring, wherein the stiffening ring is welded to the steel pipe wall to form a combined weld of a double-sided fillet weld, and the groove type is an I-type groove; the butt surfaces between the multiple stiffening ring petals are welded by gas welding;

[0060] Step 2: In the plane formed by the steel pipe and the stiffening ring, the welding rod is used to weld the stiffening ribs by high-frequency welding for reinforcement, and the size of the stiffening ribs is 300 mm×40 mm×10 mm; wherein the frequency of the high-frequency welding is 400 kHZ, and the welding speed is 25 m / min;

[0061] Among them, the welding current of arc welding is 300A, the welding voltage is 30V, and the no-load voltage is 60V; the gas welding is oxyacetylene welding, the surface is sandblasted before spray welding, and preheated at 265°C, and then sprayed and remelted after preheating. The remelting temperature is 750°C and the remelting holding time is 6s.

[0062] Comparative Example 1

[0063] The difference between this embodiment and Example 1 is that the core component does not contain Nd.

[0064] Welding tests were carried out on the welding rods of Examples 1 to 3, and the mechanical properties and moisture-proof properties were tested and analyzed. The results are shown in the table below.

[0065] Table 1. Composition percentage of electrode deposited metal of Examples 1 to 3

[0066]

[0067]

[0068] Among them, the preparation and testing methods of the test samples for the composition percentage of the electrode deposited metal are carried out in accordance with the relevant national standards for national standard welding electrodes. In order to ensure the low-temperature impact toughness of the electrode weld metal, the C content is minimized while ensuring strength and toughness, and the Ni, Cr, and Mo alloy elements are reduced. Rare earth metal Nd is added in the design to ensure the impact toughness of the weld.

[0069] Table 2 Mechanical properties of electrode deposited metal of Examples 1 to 3 and Comparative Example 1

[0070]

[0071] Among them, when testing the mechanical properties of the deposited metal in Table 2, the preparation of the test pieces was carried out in accordance with the requirements of GB / T8110. During the tensile test, the testing machine was operated in accordance with the national standard GB / T2652. The form, size and test method of the impact absorption energy specimen were in accordance with the provisions of GB / T229.

[0072] It can be seen from Table 2 that the new welding rods of the embodiments of the present invention have excellent mechanical properties and can meet the requirements of the strength of the pressure steel pipe. In order to ensure the low-temperature impact toughness of the welding rod weld metal, the C content is minimized while ensuring the strength and toughness, and the Ni, Cr, and Mo alloy elements are reduced. Compared with the comparative example 1, the welding rods of embodiments 1 to 3 are designed with the addition of rare earth metal Nd, which ensures the impact toughness of the weld, has excellent mechanical properties and welding performance, and improves the preload borne by the steel pipe after welding.

[0073] Table 3. Welding process performance of penstock stiffening rings using electrodes from Examples 1 to 3

[0074]

[0075] The evaluation criteria for arc stability are as follows: the test uses an AC welding power source, the welder is a professional welder, and a weld is performed on a test plate with a size of 200mm×80m×10mm. The remaining length of the welding rod is about 30mm. A fast photographic device is used to photograph the arc shape during welding, and the number of arc extinguishing and gasping times is observed. When the arc can burn stably and continuously without arc extinguishing and gasping, the arc is evaluated as stable, otherwise it is evaluated as unstable.

[0076] Evaluation criteria for spatter: Place a test plate with a size of 200mm×80m×10mm on a copper plate with a thickness of 6mm, and place a 400mm high cylinder surrounded by a 3mm thick copper sheet on the copper plate, with a circumference of 2000mm, to prevent the spatter from being lost. The test is carried out in the cylinder, using an AC welding power supply, and the welder is a professional welder. The welding rod melts until the remaining length is about 30mm and the arc is extinguished. Take 5 welding rods for each group of tests and weld on 5 test plates respectively. Weigh the mass of the welding rod before welding, and weigh the mass of the welding rod head and spatter after welding, with an accuracy of 0.01g. When the spatter mass accounts for less than 2% of the total mass of the molten welding rod and there are no spatter particles with a diameter of more than 2mm, it is evaluated as small spatter, otherwise it is evaluated as large spatter.

[0077] Evaluation criteria for slag removal: The test is conducted by welding two test plates with a single size of 200mm×80m×10mm in the butt groove, with a groove angle of 70 degrees and no root gap. The test uses an AC welding power supply, and the welder is a professional welder. Single-pass welding is used during welding, and the electrode does not swing. The ratio of the weld length to the length of the molten electrode is about 1:1.3, and the remaining length of the electrode is about 30mm. After the test plate is welded, the weld is immediately placed horizontally on the hammering platform facing downward to ensure that the falling ball hammers at the center of the test plate. A 2kg iron ball is placed on a 1.3m high bracket. One minute after welding, the iron ball is made to fall vertically from a fixed drop point to the center of the test plate in a free fall state with an initial velocity of zero. It is hammered five times in a row, and each group of tests is measured twice. When the weld slag can be completely removed, it is evaluated as good slag removal, otherwise it is evaluated as poor slag removal.

[0078] Evaluation criteria for slag coverage: If the slag after welding can evenly and completely cover the entire surface of the weld, it is evaluated as good slag coverage; otherwise, it is evaluated as poor slag coverage.

[0079] Evaluation criteria for weld formation: When the molten pool solidifies, the weld smoothly transitions to the workpiece, the weld bead is flat, and in the case of vertical welding, the molten pool does not drop, then the weld is evaluated as beautifully formed; otherwise, the weld is evaluated as poorly formed.

[0080] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations and descriptions here.

Claims

1. The welding rod for welding the stiffening ring of the pressure steel pipe is composed of a coating and a welding core, and is characterized in that: In terms of weight percentage, the coating comprises: 20-35% titanium dioxide, 12-26% wollastonite, 10-14% kaolinite, 8-14% siderite, 2-9% solid water glass, 3-7% electrolytic manganese, 2-6% diopside, 1-5% aluminum oxide, 0.2-0.7% magnesium oxide, 0.2-0.5% carboxymethyl cellulose, and 0.1-0.3% metallic nickel, and the total amount of each component is 100%; The welding core comprises: C≤0.03%, Si≤0.25%, Mn≤1.68%, S≤0.018%, P≤0.02%, Ni≤0.001%, Cr≤3.5%, Mo≤0.15%, Cu≤0.16%, Nd≤0.001%, and the balance is Fe; Wherein, the mass ratio of the coating to the welding core is 2:

8.

2. The welding rod for welding the stiffening ring of a pressure steel pipe according to claim 1, characterized in that: In terms of weight percentage, the drug coating includes: 24-32% titanium dioxide, 15-23% wollastonite, 11-13% kaolinite, 10-12% siderite, 4-7% solid water glass, 4-6% electrolytic manganese, 3-5% diopside, 2-4% aluminum oxide, 0.4-0.6% magnesium oxide, 0.2-0.4% carboxymethyl cellulose, and 0.2-0.3% metallic nickel, and the total amount of each component is 100%.

3. The welding rod for welding the stiffening ring of a pressure steel pipe according to claim 1, characterized in that: In terms of weight percentage, the drug coating includes: 28.7% titanium dioxide, 23% wollastonite, 13% kaolinite, 12% siderite, 7% solid water glass, 6% electrolytic manganese, 5% diopside, 4% aluminum oxide, 0.6% magnesium oxide, 0.4% carboxymethyl cellulose, and 0.3% metallic nickel.

4. The welding rod for welding the stiffening ring of a pressure steel pipe according to claim 1, characterized in that: The main component of titanium dioxide is TiO2, of which TiO2≥98%, S≤0.01%, and P≤0.01%; the particle size specifications are 100% passing through 50 mesh, more than 85% passing through 80 mesh, and no more than 40% passing through 140 mesh.

5. The welding rod for welding the stiffening ring of a pressure steel pipe according to claim 1, characterized in that: The iron carbonate content of siderite is at least 60%.

6. The welding rod for welding the stiffening ring of a pressure steel pipe according to claim 1, characterized in that: Solid water glass is a sodium silicate powder with a modulus of 3.

2.

7. A welding method for a stiffening ring of a pressure steel pipe, characterized in that: Welding is performed using the welding rod according to any one of claims 1 to 6, the welding method comprising the following steps: Step 1: using the welding rod to weld multiple stiffening ring petals to the outside of the pressure steel pipe by arc welding according to the principle of symmetrical parallel welding to form a stiffening ring, wherein the stiffening ring is welded to the steel pipe wall to form a combined weld of a double-sided fillet weld, and the groove type is an I-type groove; the butt surfaces between the multiple stiffening ring petals are welded by gas welding; Step 2: In the plane formed by the steel pipe and the stiffening ring, the welding rod is used to weld the stiffening ribs by high-frequency welding for reinforcement, and the size of the stiffening ribs is 300 mm×40 mm×10 mm; Among them, the gas welding is oxyacetylene welding, the surface is sandblasted before spray welding, and spray welding remelting is performed after preheating to 265°C.

8. The welding rod for welding the stiffening ring of a pressure steel pipe according to claim 7, characterized in that: In step 2, the frequency of high frequency welding is 350-400 kHz, and the welding speed is 20-25 m / min.

Images