Ship pipeline efficient combination welding method

Abstract

The invention provides an efficient combination welding method for ship pipelines. The efficient combination welding method comprises the following steps of preparation before welding, polishing and cleaning of rust and greasy dirt in a pipe groove and a welding area within the range of 20 mm, pipe assembling and tackling and welding flux baking. Two sections of pipes to be welded are placed on the roller carrier, and the distance between the two sections of pipes is adjusted to prepare for welding; the roller carrier can drive the pipe to rotate around the central axis of the pipe; welding is conducted on the pipe, CO2 gas shielded welding is conducted on the bottom layer through solid welding wires, and automatic submerged arc welding is conducted on the filling cover face layer. The welding efficiency can be improved by more than two times, and the welding quality is remarkably improved; labor intensity is greatly reduced, and arc light radiation and welding smoke do not exist in the submerged automatic arc welding process.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a high-efficiency combined welding method for ship pipelines. Background Art

[0002] At present, the straight pipe butt welding production adopts the method of GTAW (bottom layer tungsten inert gas welding) + FCAW (filling cover layer CO2 flux-cored welding wire). The welding production efficiency needs to be improved, the labor intensity is high, the arc radiation and smoke are large during the welding process, and the welding quality is greatly affected by factors such as the welder's skill level and the working environment temperature. Summary of the invention

[0003] In order to solve the technical problems existing in the prior art, the present invention provides a ship pipeline high-efficiency combined welding method, comprising the following steps:

[0004] Preparation before welding: prefabricate the pipe groove, clean the rust and oil stains within 20mm of the pipe groove and welding area, and bake the flux;

[0005] Place the two sections of pipe to be welded on the roller frame, adjust the distance between the two sections of pipe, and prepare for welding; the roller frame can drive the pipe to rotate around its own central axis;

[0006] Welding of pipes, including the base CO 2 Gas shielded welding with solid wire and filling and covering layer with submerged arc automatic welding.

[0007] Furthermore, the bottom layer CO 2 When welding with gas shielded solid wire, the single-sided welding and double-sided forming method is adopted. The positioning welding is directly spot-welded at four places in the front groove of the pipe. The positioning welding requires the root to be fully welded and the back to be well formed. Welding defects beyond the allowable specifications are not allowed, and both ends are polished into a slope shape.

[0008] Arc welding starts at the tack weld, the roller frame drives the pipe to rotate, and the welding position is fixed at the downhill welding position;

[0009] During welding, the welder swings left and right in a small zigzag shape to achieve a smooth front weld and good fusion of the back weld.

[0010] Furthermore, the process parameters of the CO2 gas shielded welding solid wire for the base layer include:

[0011] Welding current 105~125A, arc voltage 21~22V, welding speed 108mm / min.

[0012] Furthermore, CO 2 Gas shielded welding machine adopts DC reverse connection, CO 2Gas flow rate 15 ~ 25L / min, solid wire grade GML-56, wire diameter The wire extension is 10 to 15 mm.

[0013] Furthermore, the root assembly reserved gap d = 3 ~ 4mm, in order to achieve the purpose of efficient welding, the gap assembly requirement as far as possible to meet the lower limit value, reducing the amount of weld metal deposition.

[0014] Furthermore, the filling and capping layer is welded by submerged arc automatic welding. Before welding, the submerged arc welding trolley is fixed on the mobile platform, the welding wire and the infrared guide light are aligned on the same straight line, and the welding wire is at the center of the weld during welding;

[0015] When welding on the pipe annular seam, it is impossible to set arc-starting plate and arc-ending plate. Arc-starting and arc-ending can only be performed on the formal weld. When arc-starting, the arc is ignited first, and then the roller frame is started to drive the pipe cylinder to rotate. When arc-ending, the arc is welded 10mm to 20mm past the arc-starting end. When the arc-starting section weld is completely melted through, the arc can be ended and welding can be stopped.

[0016] Adjust the welding process parameters based on the thickness of the previous weld and the thickness of the weld to be welded.

[0017] Furthermore, the filling and covering layers in the weld are filling layer 1, filling layer 2, and filling layer 3 from bottom to top, and the outermost side of the weld is the parallel covering layer 1 and the covering layer 2.

[0018] Furthermore, the welding process of the submerged arc automatic welding of the filling and covering layer includes:

[0019] Filling layer 1: welding current 400-420A, arc voltage 25-26V, welding speed 517mm / min;

[0020] Filling layer 2: welding current 525-545A, arc voltage 26-27V, welding speed 498mm / min;

[0021] Filling layer 3: welding current 540-560A, arc voltage 26-27V, welding speed 526mm / min;

[0022] Cover layer 1: welding current 570-580A, arc voltage 26-28V, welding speed 522mm / min;

[0023] Cover layer 2: welding current 500-520A, arc voltage 25-26V, welding speed 550mm / min.

[0024] Furthermore, the DC reverse connection of the submerged arc automatic welding machine, the welding wire diameter The welding current range is 400~580A, the arc voltage range is 25~27V, and the welding speed is 517mm / min~550mm / min.

[0025] Furthermore, when welding the outer seam of the pipe, the welding wire is in a downhill position and deviates from the vertical center line of the pipe by 15 to 30 mm. The appropriate offset distance should be adjusted according to the welding speed.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The welding efficiency of the present invention can be increased by more than 2 times, and the welding quality can be significantly improved; the labor intensity is reduced to a great extent, and there is no arc radiation and welding smoke in the submerged arc automatic welding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the welding wire position during welding of the present invention;

[0029] Figure 2 It is a schematic diagram of the weld position of the submerged arc welding of the filling cover layer of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0031] The efficient combined welding method for ship pipelines proposed in this application comprises the following steps:

[0032] 1. Preparation before welding

[0033] Preparation before welding includes grinding and cleaning the groove of the pipe joint and the rust and oil stains within 20mm of the welding area, fixing the pipe assemblies, and baking the flux.

[0034] 2. Roller rack

[0035] The roller frame is a necessary equipment for pipe girth welding. The motor drives the active roller through the reducer. The active roller rotates the pipe barrel by friction. The roller frame can adjust the roller speed, which can change the pipe barrel speed, that is, change the welding speed. The distance between the two rollers can be adjusted to meet the needs of pipes of different diameters.

[0036] 3. Wire position (wire offset distance) (see Figure 1 )

[0037] When submerged arc welding is performed in a flat welding position, the molten pool cools and solidifies in a horizontal position, and the weld is well formed. When submerged arc welding is performed in a circumferential seam, the molten pool is formed from the beginning to solidification. Because the roller frame is constantly rotating, the spatial position is also constantly changing. If the welding wire is at the highest point of the weld, the faster welding speed will cause the molten metal formed by the molten pool to solidify from a horizontal position to an inclined position, which will result in poor weld formation. Therefore, when welding the circumferential seam, the correct welding wire position is that the molten pool rotates with the pipe to a horizontal position to solidify, and the weld is best formed. When welding the outer seam of the pipe, the welding wire should be in a downhill position offset from the vertical center line of the pipe by 15 to 30 mm. The appropriate offset distance should be adjusted according to the speed of the welding. If the offset distance is too large, the molten pool will cool and solidify before reaching the horizontal position; if the offset distance is too small, the molten pool will cool and solidify after passing the horizontal position. Both situations will result in poor weld formation.

[0038] The following are the processes and parameters of a specific embodiment of this application:

[0039] The pipe material is 20# seamless steel pipe, with a diameter of 508mm, a wall thickness of 13mm, a single-side groove angle of 30°, and a welding position of 1G (achieved by rotating the roller frame). The CO2 gas shielded welding machine adopts DC reverse connection, CO2 gas flow rate of 15-25L / min, solid wire brand GML-56, wire diameter The wire extension is 10-15mm. The root assembly reserved gap d = 3-4mm. In order to achieve the purpose of efficient welding, the gap assembly requirement should meet the lower limit as much as possible to reduce the amount of weld metal deposition. The welding current range is 400-580A, the arc voltage range is 25-27V, and the welding speed is 517mm / min-550mm / min (the welding speed = the rotation speed of the roller frame).

[0040] 1. GMAW (base CO2 gas shielded welding solid wire) welding

[0041] When GMAW (base CO2 gas shielded welding solid wire) is welded, a single-sided welding and double-sided forming method is adopted. The tack welding is directly spot-welded at four places in the front groove of the pipe. The tack welding requires the root to be fully welded and the back side to be well formed. Welding defects beyond the specification are not allowed. The tack welding length is about 30mm, and both ends are polished into a slope shape so that the formal weld joint is well fused. Arc welding starts at the tack welding point, the roller frame drives the pipe to rotate, and the welding position is fixed at the downhill welding position (clock 1 to 2 o'clock position). Compared with other welding positions, better back side forming and good welding efficiency can be obtained (the flat welding position is prone to weld penetration and weld nodules, and the vertical welding position has a long welding time and low efficiency). During welding, a small amplitude zigzag swing can be made left and right to achieve the requirements of flat front weld and good back weld fusion. The welding current and arc voltage must be fully matched to obtain a stable welding arc and good welding quality.

[0042] Reference range of welding process parameters:

[0043] Welding current 105~125A arc voltage 21~22V welding speed 108mm / min.

[0044] 2.SAW (submerged arc automatic welding of filling and covering layer) welding

[0045] Before welding, fix the submerged arc welding trolley on the mobile platform, calibrate the welding wire and the infrared guide light on the same line, and the welding wire should be in the center of the weld during welding. It is impossible to set arc starting plate and arc ending plate when welding on the pipe circumferential seam. Arc starting and arc ending can only be performed on the formal weld. When starting the arc, ignite the arc first, then start the roller frame to drive the pipe cylinder to rotate. When ending the arc, weld about 10mm to 20mm past the arc starting end and completely melt the arc starting section weld before ending the arc and stopping welding. In order to improve welding efficiency, the arc starting section weld and the interlayers of each weld do not need to be polished or carbon planed. After welding, the RT non-destructive testing welding quality fully meets the requirements, and there are no excessive welding defects. Adjust the welding process parameters based on the thickness of the previous weld and the thickness of the next weld to be welded. For the layout of the filling and covering layer, refer to Figure 2 Each weld of the filling layer is stacked layer by layer from bottom to top (1-4), and each weld of the cover layer is arranged in parallel according to the width of the weld (5-6).

[0046] In one embodiment, there are three filling layers and one cover layer with two layers. The specific reference range of welding process parameters is:

[0047] Filling layer 1: welding current 400~420A arc voltage 25~26V welding speed 517mm / min

[0048] Filling layer 2: welding current 525~545A arc voltage 26~27V welding speed 498mm / min

[0049] Filling layer 3: welding current 540~560A arc voltage 26~27V welding speed 526mm / min

[0050] Cover layer 1: welding current 570~580A arc voltage 26~28V welding speed 522mm / min

[0051] Cover layer 2: welding current 500~520A arc voltage 25~26V welding speed 550mm / min.

[0052] In summary, the above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. All equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification are within the scope covered by the patent of the present invention.

Claims

1. A ship pipeline high-efficiency combined welding method, characterized in that: The following steps are involved: Preparation before welding: prefabricate the pipe groove, clean the rust and oil stains within 20mm of the pipe groove and welding area, and bake the flux; Place the two sections of pipe to be welded on the roller frame, adjust the distance between the two sections of pipe, and prepare for welding; the roller frame can drive the pipe to rotate around its own central axis; The pipes are welded, including the base layer CO2 gas shielded welding solid wire welding, and the filling and covering layer submerged arc automatic welding.

2. The method according to claim 1, characterized in that: When welding the bottom layer with CO2 gas shielded welding solid wire, the single-sided welding and double-sided forming method is adopted. The positioning welding is directly spot-welded at four places in the front groove of the pipe. The positioning welding requires the root to be fully welded and the back to be well formed. Welding defects beyond the allowable specifications are not allowed, and both ends are ground into a slope shape. Arc welding starts at the tack weld, the roller frame drives the pipe to rotate, and the welding position is fixed at the downhill welding position; During welding, the welder swings left and right in a small zigzag shape to achieve a smooth front weld and good fusion of the back weld.

3. The method according to claim 2, characterized in that The process parameters of CO2 gas shielded welding solid wire welding for base layer include: Welding current 105~125A, arc voltage 21~22V, welding speed 108mm / min.

4. The method according to claim 3, characterized in that: The CO2 gas shielded welding machine adopts DC reverse connection, CO2 gas flow rate 15 ~ 25L / min, solid wire brand GML-56, wire diameter The wire extension is 10 to 15 mm.

5. The method according to claim 4, characterized in that: The root assembly reserved gap d = 3 ~ 4mm. In order to achieve the purpose of efficient welding, the gap assembly requirement should meet the lower limit as much as possible to reduce the amount of weld metal deposition.

6. The method according to claim 1, characterized in that: Fill the cover layer with submerged arc automatic welding. Before welding, fix the submerged arc welding trolley on the mobile platform, align the welding wire and the infrared guide light on the same straight line, and keep the welding wire at the center of the weld during welding. When welding on the pipe annular seam, it is impossible to set arc-starting plate and arc-ending plate. Arc-starting and arc-ending can only be performed on the formal weld. When arc-starting, the arc is ignited first, and then the roller frame is started to drive the pipe cylinder to rotate. When arc-ending, the arc is welded 10mm to 20mm past the arc-starting end. When the arc-starting section weld is completely melted through, the arc can be ended and welding can be stopped. Adjust the welding process parameters based on the thickness of the previous weld and the thickness of the weld to be welded.

7. The method according to claim 6, characterized in that: The filling and covering layers in the weld are filling layer 1, filling layer 2, and filling layer 3 from bottom to top, and the outermost side of the weld is the parallel covering layer 1 and covering layer 2.

8. The method according to claim 7, characterized in that The welding process of submerged arc automatic welding of filling and covering layer includes: Filling layer 1: welding current 400-420A, arc voltage 25-26V, welding speed 517mm / min; Filling layer 2: welding current 525-545A, arc voltage 26-27V, welding speed 498mm / min; Filling layer 3: welding current 540-560A, arc voltage 26-27V, welding speed 526mm / min; Covering layer 1: welding current 570-580A, arc voltage 26-28V, welding speed 522mm / min; Cover layer 2: welding current 500-520A, arc voltage 25-26V, welding speed 550mm / min.

9. The method according to claim 8, characterized in that: Submerged arc automatic welding machine DC reverse connection, welding wire diameter The welding current range is 400~580A, the arc voltage range is 25~27V, and the welding speed is 517mm / min~550mm / min.

10. The method according to claim 1, characterized in that: When welding the outer seam of the pipe, the welding wire is in a downhill position and offset from the vertical center line of the pipe by 15 to 30 mm. The appropriate offset distance should be adjusted according to the welding speed.

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