All-position automatic welding method for low-alloy pressure steel pipe with base plate groove structure

Abstract

The invention relates to an all-position automatic welding method for a low-alloy pressure steel pipe with a base plate groove structure, which mainly comprises the following steps of: processing a butt-joint groove in the form of an overflowing surface V-shaped groove with a groove angle of 50 degrees, adhering a ceramic pad or a steel base plate to the outer wall, uniformly controlling an assembly gap to be 5mm, and welding the butt-joint groove; after the groove is machined, a surface hardening layer and oxides are cleaned and polished in time until metallic luster is leaked, the inner side and the edge position 50 mm of the groove are cleaned and polished before welding, automatic welding equipment is adopted for all-position automatic welding, and the proportion of mixed gas used for welding is 80% of Ar: 20% of CO2. Through test verification, the pressure steel pipe installation circular seam adopts a single-face all-position automatic welding process, the strength of the circular seam has enough safety margin, the requirements of special working conditions such as load shedding of a pumped storage unit are met, and the achievement can be popularized and applied in engineering after review and identification.

Description

Technical Field

[0001] The invention belongs to the technical field of welding pressure pipes in pumped storage power stations, and in particular relates to a full-position automatic welding method for low-alloy pressure steel pipes with a backing plate groove structure. Background Art

[0002] Pumped storage power stations have higher energy conversion efficiency and greater peak load regulation capacity. They are currently the most mature, most economically efficient, most flexible, safest, longest-lived, least environmentally polluting, and most widely used energy storage technologies. With the transformation of energy structure, pumped storage power stations have developed rapidly.

[0003] At present, the pressure steel pipes of pumped storage power stations are mostly welded by submerged arc welding or on-site arc welding or gas shielded welding. After the front seam welding is completed, the back seam needs to be cleaned and polished by carbon arc gouging before welding the back seam. The operation is labor-intensive, costly, and relatively inefficient. Welding operations are required on both sides of the weld, which invisibly increases the cross-sectional size of the water tunnel excavation. It is urgent to explore the feasibility of the full-position automatic welding process of the pressure steel pipe with pad groove structure of the pumped storage power station. The full-position automatic welding technology of the pressure pipeline of the pumped storage power station can reduce the requirements for the technical level of the welder, reduce the labor intensity and safety risks of the welder, greatly improve the working conditions of the workers, improve the welding efficiency, and appropriately reduce the excavation section of the water tunnel and the amount of concrete backfilling. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method for full-position automatic welding of a low-alloy pressure steel pipe with a pad groove structure, which is characterized by processing the groove on the inner side of the pressure steel pipe for single-sided welding and double-sided forming. This welding method has been tested through a large number of welding tests and can effectively guarantee the performance of the welded joint.

[0005] The technical solution of the present invention is: A method for full-position automatic welding of a low-alloy pressure steel pipe with a backing plate groove structure has the following specific steps: Step 1: Process the butt groove. The groove form is a V-shaped groove on the flow surface. The groove angle is 50° and there is no blunt edge. After the groove is processed, the surface hardened layer and oxides are cleaned and polished in time until the metallic luster is exposed; Step 2: The gap between the two groups is evenly controlled at 5mm, and the outer wall is affixed with a ceramic pad or a steel pad; Step 3: Welding: Before welding, clean and polish the inner side of the groove and the edge position of 50mm. Use automatic welding equipment for full-position automatic welding. The mixed gas ratio used for welding is 80% Ar: 20% CO2.

[0006] Furthermore, in step 1, the groove angle is 50°, and the allowable deviation range is ±3°.

[0007] Furthermore, the welding equipment used is A-230 or MG-500plus full-position automatic welding equipment.

[0008] Furthermore, the welding equipment uses JQ.YJ501-1M welding wire with a diameter of φ1.2mm. The flat welding current of JQ.YJ501-1M welding material is 180A~240A, the welding voltage is 24V~28V, and the welding speed is 5~14cm / min. The vertical welding current is 180A~240A, the welding voltage is 24V~28V, and the welding speed is 5~14mm / min. The overhead welding current is 180A~240A, the welding voltage is 24V~28V, and the welding speed is 5~14mm / min.

[0009] Furthermore, the welding equipment uses CHT711M welding wire with a diameter of φ1.2mm, a flat welding current of 220A~280A, a welding voltage of 24V~28V, and a welding speed of 7~16cm / min, a vertical welding current of 220A~280A, a welding voltage of 24V~28V, and a welding speed of 7~16mm / min, and an overhead welding current of 220A~280A, a welding voltage of 24V~28V, and a welding speed of 7~16mm / min.

[0010] The invention discloses a construction method for full-position automatic welding of a low-alloy pressure steel pipe with a bevel structure having a pad. By controlling the bevel form, welding process parameters, welding equipment, gas ratio, etc., an A-230 or MG-500plus full-position automatic welding equipment is adopted. The welding quality is verified by experiments and the product welding is reliable. The requirements on the technical level of welders are reduced, the labor intensity and safety risks of welders are reduced, the working conditions of workers are greatly improved, the welding efficiency is improved, the excavation section of a water conveyance tunnel and the amount of concrete backfilling engineering can be appropriately reduced, and an automatic welding solution and technical specifications are provided for the installation circumferential seam welding of pressure steel pipes in pumped storage power stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the groove structure of the construction method of full-position automatic welding of the present invention. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment.It will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.In the embodiment, if specific techniques or conditions are not indicated, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specification.If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained by purchase.

[0013] At the same time, the terms such as "inside", "outside", "deviation", "large", "small", etc. cited in this specification are only for the convenience of description to be clearer, and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of implementation of the present invention without substantially changing the technical content. Example

[0014] A construction method for full-position automatic welding of low-alloy pressure steel pipe with backing plate groove structure: Step 1: A construction method for full-position automatic welding of low-alloy pressure steel pipe with backing plate groove structure. The groove form is a V-shaped groove on the flow surface, the groove angle is 50°, the allowable deviation range is ±3°, and there is no blunt edge. For details, see the groove diagram Figure 1 After groove processing, the surface hardened layer and oxides shall be cleaned and polished in time until the metallic luster is revealed, and there shall be no defects on the groove processing surface.

[0015] Step 2: When assembling the pressure steel pipe, the gap between the butt grooves should be evenly controlled at 5mm, and the outer wall should be affixed with a ceramic pad or a steel plate. Before welding, the inner side of the groove and the edge position of 50mm should be cleaned and polished. Automatic welding equipment should be used for full-position automatic welding. The mixed gas ratio used for welding is 80% Ar: 20% CO2.

[0016] Step 3: The welding process parameters must strictly follow the welding process instructions confirmed by the welding process assessment.

[0017] Preferably, the welding equipment used is A-230 or MG-500plus full-position automatic welding equipment.

[0018] Preferably, the welding equipment uses JQ.YJ501-1M welding wire with a diameter of φ1.2mm, a flat welding current of 180A~240A, a welding voltage of 24V~28V, and a welding speed of 5~14cm / min, a vertical welding current of 180A~240A, a welding voltage of 24V~28V, and a welding speed of 5~14mm / min, and an overhead welding current of 180A~240A, a welding voltage of 24V~28V, and a welding speed of 5~14mm / min.

[0019] Preferably, the welding wire used in the welding equipment is CHT711M, with a diameter of φ1.2mm, and the welding current for flat welding is 220A-280A, the welding voltage is 24V-28V, and the welding speed is 7-16cm / min, the vertical welding current is 220A-280A, the welding voltage is 24V-28V, and the welding speed is 7-16mm / min, and the overhead welding current is 220A-280A, the welding voltage is 24V-28V, and the welding speed is 7-16mm / min. See the table below for details:

[0020] The present invention conducts a hydraulic strength blasting test on a pressure steel pipe model structure welded from a Q355 steel plate with a thickness of 22 mm, tests and compares the strength mechanical properties of steel pipes with various groove pad forms (ceramic, steel plate), different welding materials and welding methods, obtains the stress strain data of the weld and heat-affected zone within the allowable stress range of the steel pipe, and obtains the section yield load limit under extreme conditions and the safety margin data of different welding methods. The test completes the full-position automatic welding welding process assessment of the pressure steel pipe with pad groove structure, and provides automatic welding solutions and technical specifications for the installation of circumferential seam welding of pressure steel pipes in pumped storage power stations.

[0021]

[0022] The hydraulic strength blasting test was carried out on the pressure steel pipe model structure welded by Q355 steel plates with a thickness of 22 mm. The test results met the expectations of the plan, and the final blasting pressure was 15.8 MPa. Under the hydraulic blasting condition, the calculated blasting pressure was between 15.69 and 19.2 MPa, and the actual blasting value of 15.8 MPa had a small error. The blasting point of the hydraulic test was located between point 4 and point 5 in area D, and the blasting pressure value was 15.8 MPa, which was 0.11 MPa lower than the lowest estimated blasting pressure value of 15.69 MPa calculated by finite element analysis.

[0023] Test data show that the full-position automatic welding method meets the relevant welding technical requirements. The penstock installation ring seam adopts a single-sided full-position automatic welding process. The ring seam strength has sufficient safety margin to meet the requirements of special working conditions such as load shedding of pumped storage units. After review and appraisal, the results can be promoted and applied in engineering projects.

[0024] In summary, the construction method of full-position automatic welding of low-alloy pressure steel pipes with a bevel structure with a pad of the present invention controls the bevel form, welding process parameters, welding equipment, gas ratio, etc., adopts A-230 or MG-500plus full-position automatic welding equipment, the welding wire is JQ.YJ501-1M or CHT711M, and the diameter is φ1.2mm. The welding quality is verified by experiments and the product welding is reliable. It can reduce the requirements on the technical level of welders, reduce the labor intensity and safety risks of welders, greatly improve the working conditions of workers, improve welding efficiency, and appropriately reduce the excavation section of water transfer tunnels and the amount of concrete backfilling. At the same time, it provides automatic welding solutions and technical specifications for the installation of circumferential seam welding of pressure steel pipes in pumped storage power stations.

[0025] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A full-position automatic welding method for a low-alloy pressure steel pipe with a backing plate groove structure, characterized in that: The steps include: Step 1: Process the butt groove. The groove form is a V-shaped groove on the flow surface with a groove angle of 50°. After the groove is processed, the surface hardened layer and oxides are cleaned and polished in time until the metallic luster is exposed; Step 2: The gap between the two groups is evenly controlled at 5mm, and the outer wall is affixed with a ceramic pad or a steel pad; Step 3: Welding: Before welding, clean and polish the inner side of the groove and the edge position of 50mm. Use automatic welding equipment for full-position automatic welding. The mixed gas ratio used for welding is 80% Ar: 20% CO2.

2. The all-position automatic welding method for low alloy pressure steel pipe with backing plate groove structure according to claim 1 is characterized in that: In step 1, the groove angle is 50°, and the allowable deviation range is ±3°.

3. The all-position automatic welding method for low alloy pressure steel pipe with backing plate groove structure according to claim 1 is characterized in that: The welding equipment used is A-230 or MG-500plus full-position automatic welding equipment.

4. The all-position automatic welding method for low alloy pressure steel pipe with backing plate groove structure according to claim 3 is characterized in that: The welding equipment uses JQ.YJ501-1M welding wire with a diameter of φ1.2mm. The flat welding current of JQ.YJ501-1M welding material is 180A~240A, the welding voltage is 24V~28V, and the welding speed is 5~14cm / min. The vertical welding current is 180A~240A, the welding voltage is 24V~28V, and the welding speed is 5~14mm / min. The overhead welding current is 180A~240A, the welding voltage is 24V~28V, and the welding speed is 5~14mm / min.

5. The all-position automatic welding method for low alloy pressure steel pipe with backing plate groove structure according to claim 3 is characterized in that: The welding equipment uses CHT711M welding wire with a diameter of φ1.2mm. The flat welding current is 220A~280A, the welding voltage is 24V~28V, and the welding speed is 7~16cm / min. The vertical welding current is 220A~280A, the welding voltage is 24V~28V, and the welding speed is 7~16mm / min. The overhead welding current is 220A~280A, the welding voltage is 24V~28V, and the welding speed is 7~16mm / min.

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