CN116900447A - A corrosion-resistant surface modification method for pressure vessel flange sealing surfaces - Google Patents

Abstract

The invention discloses a surface modification method for corrosion resistance of a flange sealing surface of a pressure vessel, which belongs to the technical field of metal flange processing and comprises the following steps: the method comprises the steps of polishing a region to be overlaid on the surface of a flange, which is made of Q345, removing greasy dirt, rust and oxide on the surface of the flange, installing the flange on an L-shaped positioner, clamping by adopting a three-grip chuck, keeping a welding gun motionless in the welding process, rotating the positioner, preheating the surface of the flange by adopting a silica gel electric heating belt, overlaying by adopting a CMT welding power supply according to the sequence of an R angle region, a bottom plane region and a final inclined plane region on the basis of the U-shaped structural characteristics of the sealing surface of the flange and the L-shaped positioner, and placing the overlaid flange into a heat treatment furnace for annealing.

Description

A corrosion-resistant surface modification method for pressure vessel flange sealing surfaces

Technical field

The present invention mainly relates to the technical field of metal flange processing, and is specifically a corrosion-resistant surface modification method for the flange sealing surface of a pressure vessel.

Background technique

Flange is also called flange plate or flange. Flange is a part that connects shafts to each other. It is used for the connection between pipe ends. It is also used as a flange on the inlet and outlet of equipment. It is used for two The connection between equipment, such as reducer flange, any connecting parts that are connected by bolts on the two planes and closed at the same time, are generally called "flanges", such as the connections of ventilation ducts. These parts can be called "flanges" Flange parts”.

With the continuous development of manufacturing technology and the increasing requirements for automation in the petrochemical pressure vessel industry, new challenges have been posed to product manufacturing. The surfacing of the corrosion-resistant layer on the flange sealing surface of petrochemical pressure vessels is one of the important links in production. Welding quality and production cycle are particularly critical.

Traditional flange sealing surface surfacing uses manual arc welding technology. After surfacing, the sealing surface is uneven, difficult to process, and takes a long time to process. At the same time, PT flaw detection after sealing surface processing often has defects, and the repair rate is high, which increases the cost. Production cost and production cycle. The heat input when using manual arc welding process for flange sealing surface surfacing is relatively large. Generally, more time is needed for inter-pass and inter-layer cooling, otherwise it will cause flange deformation and corrosion resistance of the surfacing layer. decline, eventually leading to unqualified workpiece manufacturing, increasing production costs and production cycles.

Contents of the invention

The technical solution of the present invention aims at the technical problem that the existing technical solutions are too single, and provides a solution that is significantly different from the existing technical solutions. Specifically, the present invention mainly provides a corrosion-resistant surface modification method for the sealing surface of the pressure vessel flange. , to solve the technical problems of the current manual arc welding process of the flange sealing surface proposed in the above-mentioned background technology. The sealing surface after surfacing is uneven, difficult to process, and takes a long time to process.

The technical solutions adopted by the present invention to solve the above technical problems are:

A corrosion-resistant surface modification method for a pressure vessel flange sealing surface, including the following steps:

Step 1: Grind and polish the area to be welded on the surface of the pressure vessel flange;

Step 2: Install the flange on the L-shaped positioner and clamp it;

Step 3: Use silicone heating tape to preheat the flange surface;

Step 4: The U-shaped structure based on the flange sealing surface is positioned with the L-shaped positioner. The U-shaped structure includes the R corner area, the bottom plane area and the slope area. CMT is used in sequence for the R corner area, the bottom plane area and the slope area. The welding power source performs surfacing welding, and the protective gas bottle is located on one side of the shell of the CMT welding power source;

Step 5: Put the surfacing flange into the heat treatment furnace for annealing treatment.

Further, preheating the flange surface with the silicone heating tape in step 3 includes: evenly laying the silicone heating tape on the flange surface for heating, where the preheating temperature is 100-150°C and the preheating time is 0.5- 1h.

Further, the surfacing of the R corner area described in step 4 includes the inner R corner and the outer R corner. First, turn the slewing mechanism of the L-shaped positioner, place the flange vertically, and then adjust the welding gun to the 12 o'clock position of the inner R corner. The position is 67° to the horizontal and welded. After welding the inner R corner, adjust the welding gun to the 6 o'clock position of the outer R corner and 67° to the horizontal for welding (the welding gun is installed on the robot's mechanical arm).

Further, the surfacing of the bottom plane area described in step 4 includes:

First, turn the L-shaped positioner so that the flange is in a horizontal position and the welding gun is adjusted vertically downward, and then weld from the edge of the inner R corner area to the edge of the outer R corner area.

Further, the bevel area described in step 4 includes an inner bevel and an outer bevel. First, turn the rotary mechanism of the L-shaped positioner so that the flange is 23° from the vertical direction and the welding gun is kept vertically downward, and then the welding gun is adjusted to the inside. Weld the bevel at the 12 o'clock position. After welding the inner bevel, adjust the welding gun to the 6 o'clock position of the outer bevel for welding.

Further, the R corner area, the bottom plane area and the bevel area are surfacing sequentially as described in step 4. The R corner area is surfacing first, then the bottom plane area is surfacing, and finally the bevel area is surfacing ;

Among them, during the welding process of a single pass weld, the length of rotation of the L-type positioner is the full circle plus the length of 5-10mm. The overlap rate of adjacent welds on the same layer is 40%. The overlap rate of welds on different layers The arc starting point position is staggered by 1cm, and the inter-pass weld temperature is maintained between 100°C and 150°C.

Further, the annealing treatment in step 5 includes placing the surfacing flange into a heat treatment furnace, where the annealing parameters are a heating rate of 100°C/h, a holding time of 2-4h, and a cooling rate of 50°C/h. Cool to below 300℃ for air cooling

Compared with the prior art, the beneficial effects of the present invention are:

Through the surface modification process of the corrosion resistance of the pressure vessel flange sealing surface, the present invention achieves a smooth surface of the sealing surface after surfacing, which facilitates processing, reduces the processing time, and effectively avoids the traditional processing of the sealing surface. Finally, PT flaw detection often has defects and high repair rates, which reduces production costs and production cycles.

(2) The present invention uses CMT to weld the corrosion-resistant layer on the surface of the flange, which has the characteristics of high deposition efficiency, less spatter, and stable welding process. The CMT welding heat input is low, so that the flange deforms little during the welding process. , the inter-pass and inter-layer cooling time is shortened, the corrosion resistance of the cladding layer is improved, the welding quality is greatly improved, the production cycle is shortened, thereby greatly reducing the production time and cost, and avoiding the heat generated during cladding in the traditional manual arc welding process. Large input can easily cause flange deformation and decreased corrosion resistance of the surfacing layer.

(3) The present invention adopts the sequence of R-angle area first, then the bottom plane area and finally the bevel area and the corresponding welding gun posture for surfacing welding, which greatly avoids the problems of non-fusion defects and uneven weld formation.

The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments.

Description of the drawings

Figure 1 is a flow chart of the pressure vessel flange sealing surface modification process of the present invention;

Figure 2 is a schematic diagram of the pressure vessel flange sealing surface modification process and device experimental platform of the present invention;

Figure 3 is a schematic diagram of the corrosion-resistant layer of the present invention;

Figure 4 is a schematic diagram of the U-shaped structure of the sealing surface of the present invention.

Description of the drawings: 1. Robot; 2. L-shaped positioner; 3. Flange; 4. CMT welding power source; 5. Protective gas cylinder; 6. Silicone electric tape; 7. Heat treatment furnace; 8. Corrosion-resistant layer.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the accompanying drawings. However, the present invention can be implemented in different forms and is not limited to what is described in the text. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

Note that when an element is said to be "anchored" to another element, it can be directly on the other element or intervening elements can be present. When an element is said to be "connected" to another element, it can be The terms "vertical," "horizontal," "left," "right," and similar expressions are used herein for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly used by one skilled in the art of the present invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments. For purposes of the invention, and not as a limitation of the invention, the term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

Please focus on the following:

Example 1

To prepare the corrosion-resistant layer surfacing on the sealing surface of 500mm flange 3, follow the following steps:

Step 1: Grind and polish the area to be surfacing on the U-shaped sealing surface of flange 3 made of Q345 to remove oil stains, rust and oxides on the surface of flange 3.

Step 2: Install flange 3 on the L-shaped positioner 2 and clamp it with a three-grip chuck. During the welding process, the welding gun remains stationary and the positioner rotates.

Step 3: In order to prevent the occurrence of welding cracks due to excessive cooling speed, lay the silicone heating tape 6 flat on the surface of the flange 3 and preheat it to 100-150°C, and the preheating time is 0.5h.

Step 4: Based on the U-shaped structural characteristics of the sealing surface of flange 3 and the cooperation of L-shaped positioner 2, surfacing welding is performed in the order of the R-angle area first, then the bottom plane area and finally the slope area.

Further, the surfacing welding of the R corner area includes the inner R corner and the outer R corner; first, turn the slewing mechanism of the L-shaped positioner 2 and place the flange 3 vertically. Then, adjust the welding gun to the 12 o'clock position of the inner R corner and 67° to the horizontal and perform welding; finally, after welding the inner R corner, adjust the welding gun to the 6 o'clock position of the outer R corner and 67° to the horizontal and proceed. welding.

Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5% CO ₂ , the shielding gas flow is 15L/min, the welding current is 140A, and the wire feeding speed is 4m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 1.5mm, and the left and right dwell time is 0.2s.

Further, the surfacing welding of the bottom plane area includes: first, rotating the L-shaped positioner 2 so that the flange 3 is in a horizontal position and adjusting the welding gun to appear vertically downward; then, proceed from the edge of the inner R corner area to the edge of the outer R corner area. welding. Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5% CO ₂ , the shielding gas flow is 15L/min, the welding current is 130A, and the wire feeding speed is 4m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 2mm, and the left and right dwell time is 0.2s.

Further, the surfacing in the bevel area includes the inner bevel and the outer bevel. First, turn the L-shaped positioner 2 slewing mechanism so that the flange 3 is 23° from the vertical direction and keep the welding gun vertically downward; then, adjust the welding gun to the inner bevel. Weld at the 12 o'clock position; finally, after welding the inner bevel, adjust the welding gun to the 6 o'clock position on the outer bevel for welding. Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5% CO ₂ , the shielding gas flow is 15L/min, the welding current is 130A, and the wire feeding speed is 4m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 2mm, and the left and right dwell time is 0.2s.

Furthermore, during the single-pass welding process, the length of rotation of the L-type positioner 2 is the full circle plus the length of 5mm. The width of the welding seam in the bottom plane and bevel area is 6.2mm. The adjacent welding seams on the same layer overlap. The connection rate is 40%, that is, the weld offset is 3.72mm each time. The arc starting points of different layers of welds are staggered by 1cm, and the inter-pass weld temperature is maintained between 100°C and 150°C.

Step 5: Put the surfacing flange 3 into the heat treatment furnace for annealing treatment. The heating rate is 100°C/h, the holding time is 2h, the cooling rate is 50°C/h, and it is cooled to below 300°C for air cooling. Eliminate residual stress caused by welding.

Example 2

To prepare the corrosion-resistant layer surfacing on the sealing surface of 800mm flange 3, follow the following steps:

Step 1: Grind and polish the area to be surfacing on the U-shaped sealing surface of flange 3 made of Q345, and remove oil stains, rust and oxides on the surface of flange 3.

Step 2: Install flange 3 on the L-shaped positioner 2 and tighten it with a three-grip chuck. During the welding process, the welding gun remains stationary and the positioner rotates.

Step 3: In order to prevent the occurrence of welding cracks due to too fast cooling rate, preheating treatment before welding is required. Lay the silicone heating tape 6 flatly on the surface of the flange 3 and preheat it to 100-150°C. The preheating time is 0.5h.

Step 4: Based on the U-shaped structural characteristics of the sealing surface of flange 3 and the cooperation of L-shaped positioner 2, surfacing welding is performed in the order of the R-angle area first, then the bottom plane area and finally the slope area.

Further, the surfacing welding of the R corner area includes the inner R corner and the outer R corner; first, turn the slewing mechanism of the L-shaped positioner 2 and place the flange 3 vertically. Secondly, adjust the welding gun to the 12 o'clock position of the inner R corner and 67° to the horizontal and perform welding. Finally, after welding the inner R corner, adjust the welding gun to the 6 o'clock position of the outer R corner and 67° to the horizontal and perform welding. , due to the increase in flange size, heat dissipation is faster during the welding process, so it is necessary to increase the heat input by increasing the current and left and right residence times. Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5%CO ₂ , the shielding gas flow is 15L/min, the welding current is 150A, and the wire feeding speed is 5m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 2.4mm, and the left and right dwell time is 0.2s.

Further, the surfacing welding of the bottom plane area includes first rotating the L-shaped positioner 2 so that the flange 3 is in a horizontal position and adjusting the welding gun to appear vertically downward, and secondly, welding from the edge of the inner R corner area to the edge of the outer R corner area, Due to the increase in flange size, heat dissipates faster during the welding process, so it is necessary to increase the heat input by increasing the current and left and right dwell times. Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5%CO ₂ , the shielding gas flow is 15L/min, the welding current is 135A, and the wire feeding speed is 5m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 2.8mm, and the left and right dwell time is 0.2s.

Further, the surfacing in the bevel area includes the inner bevel and the outer bevel. First, turn the L-shaped positioner 2 slewing mechanism so that the flange 3 is 23° from the vertical direction and keep the welding gun vertically downward. Secondly, adjust the welding gun to the inner bevel. Weld at the 12 o'clock position, and finally after welding the inner bevel, adjust the welding gun to the 6 o'clock position on the outer bevel for welding. Due to the increase in flange size, heat dissipation is faster during the welding process, so it is necessary to increase the current and the left and right dwell time. to increase heat input. Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5%CO ₂ , the shielding gas flow is 15L/min, the welding current is 135A, and the wire feeding speed is 5m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 2.8mm, and the left and right dwell time is 0.2s.

Furthermore, during the single-pass welding process, the length of rotation of the L-type positioner 2 is the full circle plus the length of 7mm. The width of the welding seam in the bottom plane and bevel area is 8.6mm. The adjacent welding seams on the same layer overlap. The welding rate is 40%, that is, each weld is offset by 5.16 mm, the arc starting points of different layers are staggered by 1 cm, and the inter-pass weld temperature is maintained between 100°C and 150°C.

Step 5: Put the surfacing flange 3 into the heat treatment furnace 7 for annealing. Since a large heat input is used during the welding process, a longer heat preservation time is required. The heating rate is 100°C/h, the holding time is 2.5h, the cooling rate is 50°C/h, and it is cooled to below 300°C for air cooling to eliminate the residual stress caused by welding.

Example 3

To prepare the corrosion-resistant layer for surfacing of the 1050mm flange 3 sealing surface, follow the following steps:

Step 1: Grind and polish the surfacing area on the surface of flange 3 made of Q345 to remove oil stains, rust and oxides on the surface of flange 3.

Step 2: Install flange 3 on the L-shaped positioner 2 and tighten it with a three-grip chuck. During the welding process, the welding gun remains stationary and the positioner rotates.

Step 3: In order to prevent the occurrence of welding cracks due to too fast cooling rate, preheating treatment before welding is required. Lay the silicone heating tape 6 flat on the surface of the flange 3 and preheat it to 100-150°C. Due to the large size of the flange, more preheating time is needed to ensure that every place can be evenly heated to the set temperature. Therefore the preheating time is set to 1h.

Step 4: Based on the U-shaped structural characteristics of the sealing surface of flange 3 and the cooperation of L-shaped positioner 2, surfacing welding is performed in the order of the R-angle area first, then the bottom plane area and finally the slope area.

Further, the surfacing welding of the R corner area includes the inner R corner and the outer R corner. First, turn the L-shaped positioner 2 slewing mechanism to place the flange 3 vertically; then, adjust the welding gun to the 12 o'clock position of the inner R corner and in line with the The horizontal angle is 67° and welding is performed; finally, after welding the inner R corner, adjust the welding gun to the 6 o'clock position of the outer R corner and the horizontal angle is 67° and weld. Due to the increase in flange size, heat dissipates faster during the welding process, so it is necessary to increase the heat input by increasing the current and left and right dwell times. Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5% CO ₂ , the shielding gas flow is 15L/min, the welding current is 160A, and the wire feeding speed is 6m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 3.5mm, and the left and right dwell time is 0.2s.

Further, the surfacing welding of the bottom plane area includes first rotating the L-shaped positioner 2 so that the flange 3 is in a horizontal position and adjusting the welding gun to appear vertically downward; then, welding is performed from the edge of the inner R corner area to the edge of the outer R corner area. Due to the increase in flange size, heat dissipates faster during the welding process, so it is necessary to increase the heat input by increasing the current and left and right dwell times. Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5% CO ₂ , the shielding gas flow is 15L/min, the welding current is 150A, and the wire feeding speed is 6m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 4mm, and the left and right dwell time is 0.2s.

Further, the surfacing in the bevel area includes the inner bevel and the outer bevel. First, turn the L-shaped positioner 2 slewing mechanism so that the flange 3 is 23° from the vertical direction and keep the welding gun vertically downward; then, adjust the welding gun to the inner bevel. Weld at the 12 o'clock position; after finally welding the inner bevel, adjust the welding gun to the 6 o'clock position on the outer bevel for welding. Due to the increase in flange size, heat dissipates faster during the welding process, so it is necessary to increase the heat input by increasing the current and left and right dwell times. Among them, the welding conditions: the welding wire is E309-16 with Φ1.2mm, the dry extension of the welding wire is 15mm, the shielding gas is 97.5% Ar+2.5% CO ₂ , the shielding gas flow is 15L/min, the welding current is 150A, and the wire feeding speed is 6m /min, the welding speed is 3mm/s, the swing length is 1.5mm, the swing deflection is 4mm, and the left and right dwell time is 0.2s.

Furthermore, during the single-pass welding process, the length of rotation of the L-shaped positioner 2 is the full circle plus the length of 10mm. The width of the welding seam in the bottom plane and bevel area is 11.4mm. The adjacent welding seams on the same layer overlap. The connection rate is 40%, that is, each weld is offset by 6.84mm, the arc starting points of different layers are staggered by 1cm, and the inter-pass weld temperature is maintained between 100°C and 150°C.

Step 5: Put the surfacing flange 3 into the heat treatment furnace 7 for annealing treatment. Due to the large heat input used in the welding process and the large size of the flange, a longer heat preservation time is required. The heating rate is 100°C/h, the holding time is 4h, the cooling rate is 50°C/h, and it is cooled to below 300°C for air cooling to eliminate the residual stress caused by welding.

The present invention has been exemplarily described above in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited by the above-mentioned manner, as long as such non-substantial improvements are adopted using the method concept and technical solution of the present invention, or the present invention is modified without improvement. If the concepts and technical solutions of the invention are directly applied to other situations, they are all within the protection scope of the invention.

Claims (7)

1. The surface modification method for the corrosion resistance of the flange sealing surface of the pressure vessel is characterized by comprising the following steps of:

step 1: polishing the to-be-welded area of the flange surface of the pressure vessel;

step 2: installing and clamping the flange on the L-shaped transformer;

step 3, preheating the surface of the flange by adopting a silica gel electric heating belt;

step 4: the U-shaped structure based on the flange sealing surface is matched with the L-shaped transformer for positioning, the U-shaped structure comprises an R-angle area, a bottom plane area and an inclined plane area, and a welding robot is adopted to sequentially build up welding on the R-angle area, the bottom plane area and the inclined plane area;

step 5: and placing the flange subjected to surfacing welding into a heat treatment furnace for annealing treatment.

2. The method for modifying the corrosion-resistant surface of a flange sealing surface of a pressure vessel according to claim 1, wherein the preheating of the flange surface by the silica gel electric heater belt in step 3 comprises: uniformly spreading the silica gel electric heating belt on the surface of the flange for heating, wherein the preheating temperature is 100-150 ℃ and the preheating time is 0.5-1h.

3. The method for modifying the corrosion resistant surface of a flange sealing surface of a pressure vessel according to claim 1, wherein the bead welding in the R-angle area of step 4 comprises an inner R-angle and an outer R-angle, wherein the flange is vertically placed by rotating a slewing mechanism of the L-type positioner, the welding gun is adjusted to an inner R-angle 12-point position and is welded with a horizontal surface at 67 °, and the welding gun is adjusted to an outer R-angle 6-point position and is welded with the horizontal surface at 67 ° after the inner R-angle is welded.

4. The method for modifying a corrosion resistant surface of a flange sealing surface of a pressure vessel according to claim 1, wherein the bottom planar area overlay welding of step 4 comprises:

the L-type positioner is first turned so that the flange is in a horizontal position and the welding gun is adjusted to assume a vertically downward position, and then welding is performed from the inside R-angle region edge to the outside R-angle region edge.

5. The method of claim 1, wherein the bevel area in step 4 comprises an inner bevel and an outer bevel, the slewing mechanism of the L-shaped positioner is rotated to make the flange at 23 ° vertical and the welding gun at a position vertically downward, the welding gun is adjusted to a position 12 on the inner bevel for welding, and the welding gun is adjusted to a position 6 on the outer bevel for welding after the inner bevel is welded.

6. The method for modifying the corrosion resistant surface of the flange sealing surface of the pressure vessel according to claim 1, wherein the surfacing of the R-angle area, the bottom plane area and the inclined surface area in the step 4 is performed sequentially, wherein the surfacing of the R-angle area is performed first, then the surfacing of the bottom plane area is performed, and finally the surfacing of the inclined surface area is performed;

in the welding process of single-pass welding seams, the rotating length of the L-shaped positioner is equal to the sum of the whole circle and the length of 5-10mm, the overlapping rate of welding seams adjacent to the same layer is 40%, the arc starting points of the welding seams of different layers are staggered by 1cm, and the temperature of the welding seams between the passes is kept between 100 ℃ and 150 ℃.

7. The method for modifying the corrosion resistant surface of the flange sealing surface of the pressure vessel according to claim 1, wherein the annealing treatment in the step 5 comprises placing the flange with the build-up welding in a heat treatment furnace, wherein the annealing parameter is that the heating speed is 100 ℃/h, the heat preservation time is 2-4h, the cooling speed is 50 ℃/h, and the flange is cooled to below 300 ℃ for air cooling.