Local heat treatment method for circumferential weld with large cross section size difference in high-pressure pipe section manufacturing
By calculating the external dimension ratio and effective wall thickness ratio of the high-pressure pipe section, we determine whether heat is needed, and setting the corresponding heat treatment process, it solves the problem that the ring weld with large cross-sectional dimensions is difficult to remove internal stress, and achieves efficient local Heat treatment improves the quality and safety of the welds.
Patent Information
- Application Number
- CN202411466015.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-02-14
AI Technical Summary
In the manufacturing of high-pressure pipe sections, ring welds with large cross-sectional size differences are difficult to effectively remove internal stress through traditional whole or local heat treatment methods, and traditional methods have problems such as complex design and waste of energy.
By calculating the external dimension ratio and the effective wall thickness ratio, determine whether heat replenishment is needed, and the heat treatment process is set based on the calculation results, including determining the location of the heating component and real-time insulation measures to achieve efficient local heat treatment.
This method can effectively eliminate internal stress generated by welding, improve the metal structure of the weld and heat-affected zone, improve the quality and safety of the weld, and avoid the problems of energy waste and design complexity.
Smart Images
Figure CN119433181A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of high-pressure pipe section manufacturing, in particular to a local heat treatment method for a girth weld with large cross-sectional size differences in the manufacturing of a high-pressure pipe section. Background Art
[0002] In the manufacture of high-pressure pipe sections, local heat treatment is an effective method for girth welds with large differences in cross-sectional dimensions. It aims to eliminate the internal stress generated by welding and improve the metal structure of the weld and heat-affected zone. This method is usually used to treat large structural parts for post-weld heat treatment to relieve stress, such as the gooseneck of a drilling rig transfer device. These parts are subjected to severe stress during operation and have residual stress after welding. Heat treatment is required to remove stress to ensure the performance and safety of the parts.
[0003] Conventional post-weld heat treatment methods include local post-weld heat treatment and overall post-weld heat treatment. During overall post-weld heat treatment, the entire workpiece is placed in a furnace for heat treatment. This heat treatment is characterized by easy temperature control and simple operation. For the manufacture of slender pipe sections, it is also possible to make a slender overall annealing furnace. According to conventional heat treatment methods, due to the high-pressure pipe section, the pipe wall thickness is large, generally forged steel pipes, and pipe fittings such as tees are also made of forgings. Therefore, in the conventional local post-weld heat treatment method, the heating device is arranged along the weld. Since the heat dissipates quickly on one side of the large cross-sectional size, even if the insulation belt is lengthened, it cannot meet the power requirements for heating and insulation. Local heat treatment is an effective treatment method for circumferential welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections. It can not only eliminate the internal stress generated by welding, but also improve the metal structure of the weld and the heat-affected zone, thereby improving the quality and safety of the weld.
[0004] However, traditional high-pressure pipeline manufacturing has the following disadvantages:
[0005] (1) If the pipe segment manufacturing will have tees and other pipe fittings welded to the pipe, and the position of the pipe fittings cannot be fixed during the pipe segment manufacturing process, the overall post-weld heat treatment must be designed according to the site location and device layout. In this case, the heterogeneous annealing furnace is not easy to design into a universal overall annealing furnace; and generally, the overall heat treatment of the high-pressure pipe segment into the furnace will have an adverse effect on the surface quality of the sealing surface of the pipe segment.
[0006] (2) Local heat treatment only heats the weld and the nearby parent material. The heating device is arranged along the weld, and there are certain requirements for the heating belt and the insulation belt;
[0007] (3) The local heat treatment method after welding of the girth weld between two workpieces with large differences in cross-sectional dimensions during the manufacturing of carbon steel or alloy steel high-pressure pipe sections. The post-weld heat treatment of this girth is generally carried out by local heat treatment. Due to the large differences in the cross-sectional dimensions of the workpieces, conventional heat treatment methods cannot guarantee the required heating and cooling rates. At the same time, the temperature difference of the insulation section cannot meet the requirements of the specification. If the overall heat treatment is performed, although the heat treatment quality can be guaranteed, it is not easy to achieve due to the large differences in the length and cross-sectional dimensions of the pipe section. Even if it can be achieved, it will cause a lot of energy waste. Summary of the invention
[0008] The purpose of the present invention is to provide a local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections, so as to solve the problem raised in the above background technology that if pipe fittings such as tees and elbows are welded to pipes during pipe section manufacturing, and the position of the pipe fittings cannot be fixed during the pipe section manufacturing process, the overall post-weld heat treatment must be designed according to the site orientation and device layout. The position of the pipe fittings of the pipe section, then this heterogeneous annealing furnace is not easy to be designed into a universal overall annealing furnace; the local heat treatment only heats the weld and the nearby parent material locally, the heating device is arranged along the weld, and there are certain requirements for the heating belt, and there are also requirements for the insulation belt. Certain requirements; the local heat treatment method after welding of the girth weld between two workpieces with large differences in cross-sectional dimensions in the manufacturing of carbon steel or alloy steel high-pressure pipe sections. The post-weld heat treatment of this girth generally adopts the local heat treatment method for post-weld heat treatment. Due to the large difference in the cross-sectional dimensions of the workpieces, conventional heat treatment methods cannot guarantee the temperature rise and fall rate requirements, and the temperature difference of the insulation section cannot meet the specification requirements. If an overall heat treatment is performed, although the heat treatment quality can be guaranteed, it is not easy to achieve due to the large differences in the length and cross-sectional dimensions of the pipe sections. Even if it can be achieved, it will cause a lot of energy waste.
[0009] To achieve the above object, the present invention provides the following technical solution: a method for local heat treatment of girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections, comprising the following steps:
[0010] Step 1: Determine the heating ratio: determine whether the carbon steel or alloy steel high-pressure pipe needs heating based on the two ratios. Specifically, determine whether heating is needed based on the calculated ratio of the outer dimensions and the ratio of the effective wall thickness, and the calculated cross-sectional dimension difference, and select the heating process.
[0011] Step 2: Process setting: Calculate the heat treatment process of supplementary heat according to the given calculation formula;
[0012] Step 3: Clarify the heat treatment requirements: determine the insulation effect requirements and the layout requirements of the heater and thermocouple respectively;
[0013] Step 4: Setting the position of the heating component: determining the position of the heater required for heating the high-pressure pipe and the position of the thermocouple;
[0014] Step 5: Real-time insulation: Real-time insulation of the local heat treatment position of the ring weld on the high-pressure pipe.
[0015] As a preferred technical solution of the present invention, the calculation formula for the heat compensation ratio in the step one is specifically ΔL=αL(t2-t1), wherein: ΔL is the thermal expansion of the pipeline, unit: mm; ɑ is the linear expansion coefficient of the pipeline, unit: mm / m·℃, for steel, this value is usually 0.012mm / m·℃ or varies according to the specific material; L is the length of the pipeline, unit: m; t2 is the maximum temperature of the heat medium in the pipeline, unit: ℃; t1 is the ambient temperature when the pipeline is installed or calculated, unit: ℃.
[0016] As a preferred technical solution of the present invention, the ratio of the outer dimensions and the ratio of the effective wall thickness calculated in step 1 is specifically set as follows: the inner radius of the high-pressure pipe is r1, the outer radius is r2, and the length is L. After the heating, the inner radius becomes r1', the outer radius becomes r2', and the length becomes L'. Since the heating is uniform, it is assumed that the increase in the inner and outer radii after the heating is the same, that is: r2'-r2=r1'-r1=Δr. At the same time, the increase in length after the heating is set to ΔL, then: L'=L+ΔL. The volume of the high-pressure pipe after the heating is set to be K times the original volume. The volume V of the Gaia tube is represented as: The volume V' after heating is: Denoting V' as KV, we get Since Δr and ΔL are unknown, we use them to represent r2', r1' and L', and simplify them into the above formula to obtain The specific ratio of the dimensions is so It should be equal to the ratio of hot money, that is:
[0017] As a preferred technical solution of the present invention, the cross-sectional dimension difference is calculated in step 1. Generally, as the diameter of the pipeline increases, the difference between the annular seam of the pipe fitting and the pipe increases. Therefore, the ratio of the cross-sectional dimensions is first calculated, where the letter a is used to represent the size of the difference. In addition, the ratio of the effective wall thickness is calculated, which is represented by the letter b.
[0018] As a preferred technical solution of the present invention, the process setting in the step 2 is specifically to determine whether it is necessary to add a supplementary heating process to realize local heat treatment based on the two constants a and b. When a≤1.2 and b≤1.5, no supplementary heating is required, and extending the insulation belt can meet the requirement; when a≥1.2 and b≤1.5, supplementary heating is required, and the insulation temperature selected by the supplementary heating heat treatment process is 0.5-0.6 times the insulation temperature of the post-weld heat treatment temperature, and the heating rate and the cooling rate are the same as the heat treatment process at the weld; when a≥1.2 and b≥2, supplementary heating is required, and the insulation temperature selected by the supplementary heating heat treatment process is 0.65-0.8 times the insulation temperature of the post-weld heat treatment temperature, and the heating rate and the cooling rate are the same as the heat treatment process at the weld.
[0019] As a preferred technical solution of the present invention, the thermal insulation effect requirement in step three is specifically that this local heat treatment method has certain requirements on the thermal insulation effect of the thermal insulation layer and the heat insulation layer. During the heating and insulation stage, the outer surface temperature of the thermal insulation layer cannot exceed 60°C.
[0020] As a preferred technical solution of the present invention, the arrangement requirement of the heater and the thermocouple in step three is specifically that the heater and the thermocouple should be arranged one-to-one, and one thermocouple controls the power regulation of one heater.
[0021] As a preferred technical solution of the present invention, the position of the heater in step four is determined specifically by the arrangement of the heater and the direction of the weld. The arrangement can be parallel to the weld direction or perpendicular to the weld direction according to the effective wall thickness of the weld. When the effective wall thickness of the weld exceeds 40 mm, the heater must be arranged perpendicular to the weld direction.
[0022] As a preferred technical solution of the present invention, the thermocouple position determination in step 4 is specifically that the thermocouple is spot welded on the workpiece, and the thermocouple and the heater cannot be in direct contact, ensuring that the temperature measured by the thermocouple is the temperature of the workpiece.
[0023] As a preferred technical solution of the present invention, the real-time insulation in step five is specifically that the width of the insulation layer exceeds the width of the heater by more than 400 mm on both sides.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] 1. The ratio of the calculated outer dimensions and the effective wall thickness is used to determine whether supplementary heat is needed. For workpieces with different cross-sectional dimensions, the segmented heat treatment process design is performed. The segmented process design is related to the difference in cross-sectional dimensions.
[0026] 2. Clarify the heat treatment requirements, set the position of the heating component, heat the heater and thermocouple, and perform stress relief heat treatment on the workpiece. This method is also used in the stabilization heat treatment of stainless steel after welding and is highly practical. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION
[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0029] See also Figure 1 The present invention provides a local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections, comprising the following steps:
[0030] Step 1: Determine the heating ratio: determine whether the carbon steel or alloy steel high-pressure pipe needs heating based on the two ratios. Specifically, determine whether heating is needed based on the calculated ratio of the outer dimensions and the ratio of the effective wall thickness, and the calculated cross-sectional dimension difference, and select the heating process.
[0031] Step 2: Process setting: Calculate the heat treatment process of supplementary heat according to the given calculation formula;
[0032] Step 3: Clarify the heat treatment requirements: determine the insulation effect requirements and the layout requirements of the heater and thermocouple respectively;
[0033] Step 4: Setting the position of the heating component: determining the position of the heater required for heating the high-pressure pipe and the position of the thermocouple;
[0034] Step 5: Real-time insulation: Real-time insulation of the local heat treatment position of the ring weld on the high-pressure pipe.
[0035] The specific calculation formula for the heat compensation ratio in step one is ΔL=αL(t2-t1), where: ΔL is the thermal expansion of the pipeline, unit: mm; ɑ is the linear expansion coefficient of the pipeline, unit: mm / m·℃, for steel, this value is usually 0.012mm / m·℃ or varies according to the specific material; L is the length of the pipeline, unit: m; t2 is the maximum temperature of the heat medium in the pipeline, unit: ℃; t1 is the ambient temperature when the pipeline is installed or calculated, unit: ℃.
[0036] The ratio of the outer dimensions and the effective wall thickness calculated in step 1 is specifically: the inner radius of the high-pressure pipe is r1, the outer radius is r2, and the length is L. After the heating, the inner radius becomes r1', the outer radius becomes r2', and the length becomes L'. Since the heating is uniform, it is assumed that the increase in the inner and outer radii after the heating is the same, that is: r2'-r2 = r1'-r1 = Δr. At the same time, the increase in length after the heating is set to ΔL, then: L' = L + ΔL. The volume of the high-pressure pipe after the heating is assumed to be K times the original volume. The volume V of the Gaia tube is marked as: The volume V' after heating is: Denoting V' as KV, we get Since Δr and ΔL are unknown, we use them to represent r2', r1' and L', and simplify them into the above formula to obtain The specific ratio of the dimensions is so It should be equal to the ratio of hot money, that is:
[0037] In step one, the difference in cross-sectional dimensions is calculated. Generally, as the diameter of the pipe increases, the difference in the annular seam between the pipe fitting and the pipe increases. Therefore, the ratio of the cross-sectional dimensions is calculated first. Here, the letter a is used to represent the size of the difference. In addition, the ratio of the effective wall thickness must be calculated, represented by the letter b.
[0038] The process setting in step 2 is specifically to determine whether it is necessary to add a supplementary heat process to achieve local heat treatment based on the two constants a and b. When a≤1.2 and b≤1.5, no supplementary heat is required, and extending the insulation belt can meet the requirement; when a≥1.2 and b≤1.5, supplementary heat is required, and the insulation temperature selected for the supplementary heat treatment process is 0.5-0.6 times the post-weld heat treatment temperature, and the heating rate and cooling rate are the same as the heat treatment process at the weld; when a≥1.2 and b≥2, supplementary heat is required, and the insulation temperature selected for the supplementary heat treatment process is 0.65-0.8 times the post-weld heat treatment temperature, and the heating rate and cooling rate are the same as the heat treatment process at the weld.
[0039] The thermal insulation effect requirements in step three specifically have certain requirements on the thermal insulation effect of the thermal insulation layer and the heat insulation layer by this local heat treatment method. During the heating and thermal insulation stages, the outer surface temperature of the thermal insulation layer cannot exceed 60°C.
[0040] The arrangement requirements of the heater and the thermocouple in step three are that the heater and the thermocouple should be arranged one by one, and one thermocouple controls the power regulation of one heater.
[0041] In step 4, the position of the heater is determined. Specifically, the arrangement of the heater and the direction of the weld can be selected to be parallel to the weld direction or perpendicular to the weld direction according to the effective wall thickness of the weld. When the effective wall thickness of the weld exceeds 40mm, the heater must be arranged perpendicular to the weld direction.
[0042] In step 4, the position of the thermocouple is determined by spot welding the thermocouple on the workpiece. The thermocouple and the heater cannot be in direct contact to ensure that the temperature measured by the thermocouple is the temperature of the workpiece.
[0043] In step 5, the real-time insulation specifically requires that the width of the insulation layer exceeds the width of the heater by more than 400 mm on both sides.
[0044] In the present invention, we first calculate the two ratios for judging whether supplementary heat is needed. Based on the calculated ratio of the outer dimensions and the ratio of the effective wall thickness, we judge whether supplementary heat is needed and select the process for supplementary heat. The heat treatment process for supplementary heat is calculated according to the given calculation formula, and the cross-sectional dimension difference is calculated. Generally, as the diameter of the pipeline increases, the difference between the annular seam of the pipe fitting and the pipe increases. Therefore, the ratio of the cross-sectional outer dimensions is calculated first, and the letter a is used here to represent the size of the difference. In addition, the ratio of the effective wall thickness is calculated, represented by the letter b. Based on these two constants, we judge whether it is necessary to add a supplementary heat process to achieve local heat treatment. When a≤1.2 and b≤1.5, supplementary heat is not needed, and extending the insulation belt can meet the requirement; when a≥1.2 and b≤1.5, supplementary heat is required, and the insulation temperature selected for the supplementary heat treatment process is 0.5-0.6 times the post-weld heat treatment temperature. The heating rate and the cooling rate are the same as those of the heat treatment process at the weld. When a≥1.2 and b≥2, supplementary heat is required, and the insulation temperature selected for the supplementary heat treatment process is the post-weld heat treatment temperature. The insulation temperature is 0.65-0.8 times of the temperature of the weld. The heating rate and the cooling rate are the same as the heat treatment process at the weld. The insulation effect requirements: This local heat treatment method has certain requirements for the insulation effect of the insulation layer and the thermal insulation layer. During the heating and insulation stages, the outer surface temperature of the insulation layer cannot exceed 60°C. The layout requirements of the heater and the thermocouple: The heater and the thermocouple should be arranged one by one, and a thermocouple controls the power adjustment of a heater. The layout of the heater and the direction of the weld can be selected parallel to the weld direction and perpendicular to the weld direction according to the effective wall thickness of the weld. When the effective wall thickness of the weld exceeds 40mm, the heater must be arranged perpendicular to the weld direction. The thermocouple should be spot welded on the workpiece. The thermocouple and the heater cannot be in direct contact to ensure that the thermocouple temperature is the workpiece temperature. The width of the insulation layer must exceed the width of the heater by more than 400mm on both sides.
[0045] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections, characterized in that: The following steps are involved: Step 1: Determine the heating ratio: determine whether the carbon steel or alloy steel high-pressure pipe needs heating based on the two ratios. Specifically, determine whether heating is needed based on the calculated ratio of the outer dimensions and the ratio of the effective wall thickness, and the calculated cross-sectional dimension difference, and select the heating process. Step 2: Process setting: Calculate the heat treatment process of supplementary heat according to the given calculation formula; Step 3: Clarify the heat treatment requirements: determine the insulation effect requirements and the layout requirements of the heater and thermocouple respectively; Step 4: Setting the position of the heating component: determining the position of the heater required for heating the high-pressure pipe and the position of the thermocouple; Step 5: Real-time insulation: Real-time insulation of the local heat treatment position of the ring weld on the high-pressure pipe.
2. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 1, characterized in that: The specific calculation formula for the heat compensation ratio in step 1 is ΔL=αL(t2-t1), wherein: ΔL is the thermal expansion of the pipeline, unit: mm; ɑ is the linear expansion coefficient of the pipeline, unit: mm / m·℃, for steel, this value is usually 0.012mm / m·℃ or varies according to the specific material; L is the length of the pipeline, unit: m; t2 is the maximum temperature of the heat medium in the pipeline, unit: ℃; t1 is the ambient temperature when the pipeline is installed or calculated, unit: ℃.
3. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 1, characterized in that: The ratio of the outer dimensions and the effective wall thickness calculated in step 1 is specifically: the inner radius of the high-pressure pipe is r1, the outer radius is r2, and the length is L. After the heating, the inner radius becomes r1', the outer radius becomes r2', and the length becomes L'. Since the heating is uniform, it is assumed that the increase in the inner and outer radii after the heating is the same, that is: r2'-r2=r1'-r1=Δr. At the same time, the increase in length after the heating is set to ΔL, then: L'=L+ΔL. The volume of the high-pressure pipe after the heating is assumed to be K times the original volume. The volume V of the Gaia high-pressure pipe is marked as: The volume V' after heating is: Denoting V' as KV, we get Since Δr and ΔL are unknown, we use them to represent r2', r1' and L', and simplify them into the above formula to obtain The specific ratio of the dimensions is so It should be equal to the ratio before the hot money replenishment, that is:
4. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 1, characterized in that: In the step 1, the cross-sectional dimension difference is calculated. Generally, as the diameter of the pipeline increases, the difference between the annular seam of the pipe fitting and the pipe increases. Therefore, the ratio of the cross-sectional dimensions is calculated first, where the letter a is used to represent the size of the difference. In addition, the ratio of the effective wall thickness is calculated, which is represented by the letter b.
5. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 4, characterized in that: The process setting in the step 2 is specifically to determine whether it is necessary to add a supplementary heating process to realize local heat treatment based on the two constants a and b. When a≤1.2 and b≤1.5, no supplementary heating is required, and extending the insulation belt can meet the requirement; when a≥1.2 and b≤1.5, supplementary heating is required, and the insulation temperature selected by the supplementary heating heat treatment process is 0.5-0.6 times the insulation temperature of the post-weld heat treatment temperature, and the heating rate and the cooling rate are the same as the heat treatment process at the weld; when a≥1.2 and b≥2, supplementary heating is required, and the insulation temperature selected by the supplementary heating heat treatment process is 0.65-0.8 times the insulation temperature of the post-weld heat treatment temperature, and the heating rate and the cooling rate are the same as the heat treatment process at the weld.
6. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 1, characterized in that: The thermal insulation effect requirement in step three specifically has certain requirements on the thermal insulation effect of the thermal insulation layer and the heat insulating layer by this local heat treatment method. During the heating and thermal insulation stages, the outer surface temperature of the thermal insulation layer cannot exceed 60°C.
7. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 1, characterized in that: The arrangement requirement of the heater and the thermocouple in the step 3 is specifically that the heater and the thermocouple should be arranged one by one, and one thermocouple controls the power regulation of one heater.
8. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 1, characterized in that: In the step 4, the position of the heater is determined. Specifically, the arrangement of the heater and the direction of the weld can be selected to be parallel to the weld direction or perpendicular to the weld direction according to the effective wall thickness of the weld. When the effective wall thickness of the weld exceeds 40 mm, the heater must be arranged perpendicular to the weld direction.
9. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 1, characterized in that: The thermocouple position determination in step 4 is specifically that the thermocouple should be spot welded on the workpiece, and the thermocouple and the heater cannot be in direct contact, ensuring that the temperature measured by the thermocouple is the temperature of the workpiece.
10. The local heat treatment method for girth welds with large cross-sectional size differences in the manufacture of high-pressure pipe sections according to claim 1, characterized in that: The real-time heat preservation in step 5 specifically means that the width of the heat preservation layer exceeds the width of the heater by more than 400 mm on both sides.