Corrugated Transformer Tanks Welding Procedure detail state the Corrugated Fins Wall Welding and Transformer Tank Bottom and Frame Welding.
1 Overview of Corrugated Transformer Tanks Welding
This process specification describes the welding requirements and relevant regulations for corrugated tank of distribution transformer.
2. Corrugated Transformer Tanks Welding preparation
1) Drawing preparation and familiarity with drawing requirements.
2) Material preparation
Prepare welding materials according to drawings, including bottom, edge and Corrugated Fins Wall.(The corrugated fin wall is made by JTFY corrugated fins wall pressing machine, and fins seam weld by JTFY auto fin wall welding machine.)
Welding wire should be stored in a dry and well ventilated place and kept by a special person.
Welding wire, groove and groove should be kept clean in the range of 10-20 mm, and no foreign matter such as rust, oil, water and paint affecting welding quality should be avoided.
3) According to the size of corrugated plate, it is necessary to determine whether preheating, preheating specification and inter-layer temperature are needed.
4) Working conditions: When the wind speed exceeds 2 m/s, welding should be stopped or windproof measures should be taken. Relative humidity in the working area should be less than 90%. Open-air welding is prohibited in rainy and snowy weather.
3. Corrugated plate welding
The parts to be welded must be rusted and greased before welding.
1) After the corrugated sheet is pressed and formed, it is necessary to weld and strengthen the circular pipe. According to the requirements, each corrugated sheet is welded together with the pipe from the front.
At the same time, three corrugated plates are spot-welded from the reverse side, i.e., the two ends and the middle. The corrugated sheet that meets any of the following requirements shall be spot welded on the reverse side.
The height of corrugated plate reaches 700 mm
The width of corrugated plate reaches 500 mm.
4. Welding of corrugated fins walls and bottom/edge of transformer tank
1) On the outside surface of the bottom of the transformer tank, draw a horizontal straight line at 5 mm from the top edge of the bottom, then put the bottom of the tank into the corrugated plate box, and then use the C-type fixture to locate accurately.
After checking whether the horizontal straight line is level with the edge of the corrugated sheet tank, spot welding is carried out to fix it.
2) Start welding from one corner. The torch is inclined 45 degrees upward. The welding joint should be on the bottom of the tank but close to the corrugated plate tank.
The surfacing material in the welding process will make the two fuse together, and the heat generated during the welding process should be absorbed by the thick and thin workpiece in the proportion of about 70%/30%.
3) Continuous welding until a corrugated sheet is welded. When the corrugated sheet and bottom of the transformer tank are welded to the end, it is required to weld on the corrugated sheet until it exceeds the edge of the bottom of the tank by about 10-20 mm, and then weld back from outside to inside to the bottom of the tank.
Ensure that the next corrugated plate is welded after the weld seam is fully fused. Continue to weld all sides of tank bottom and corrugated plate in the same way.
4) If the welding stops halfway, the welding should start from the stop point, but it is necessary to ensure that the surfacing metal of the welding start point is fully melted. Experience shows that the welding start point is the most vulnerable to leakage.
5) Then turn over the welded tank edge and the corrugated plate part of the tank. After putting the edge of the tank into the corrugated plate, check the inside height of the tank and spot welding positioning. The whole welding procedure is the same as above.
6) When the transformer tank edge is welded to the corrugated fins wall, the corrugated plate and the bottom to the end of the tank are welded to ensure safety.
The method is similar, requiring welding on the corrugated sheet until it exceeds the box and goes down along the lower edge.About 10-20 mm, and then from the bottom to the top of the tank along the end edge.
7) After the tank is welded, the leak inspection can be prepared.
transformer tank leakage test
5.Corrugated Transformer Tanks Welding defects and preventive measures
1.Defects:Weld crack
Reasons: 1. Weld depth-width ratio is too large; 2. Too narrow bead; 3. Fast cooling at weld end
Preventive Measures:1. Increase welding arc voltage and reduce welding current; 2. Slow down welding speed; 3. Appropriate filling of arc pits
2.Defects:Inclusion
Reasons:1. Short-circuit arc with multi-pass welding; 2. High walking speed
Preventive Measures:1. Clean up the residue shell carefully; 2. Reduce walking speed and increase arc voltage;
3.Defects:Air Hole
Reasons:1. Insufficient protection gas coverage; 2. Insufficient purity of protective gas; 3. Inappropriate proportioning of protective gases; 4. Welding wire pollution or workpiece pollution; 5. too high arc voltage; 6. The distance between nozzle and workpiece is too far.; 7. Gas heater does not work properly
Preventive Measures:1. Increase gas flow rate, eliminate splash in nozzle and reduce the distance between workpiece and nozzle; 2. Improving the purity of protective gas and reducing the moisture content of gas; 3. The recommended gas ratio is 80% Ar + 20% CO2. 4. Remove lubricant on welding wire or oil rust on workpiece.; 6. Reduce Voltage; 7. Reducing the Extension Length of Welding Wire; 8. Ensure that the gas heater is in good condition
4.Defects:Undercut
Reasons:1. Welding speed is too high; 2. High arc voltage or current; 3. Insufficient Residence Time; 4. Incorrect torch angle
Preventive Measures:1. Slow down welding speed; 2. Reduce voltage or current; 3. Increase the residence time at the edge of molten pool; 4. Change the angle of welding torch to make arc force drive metal flow
5.Defects:Not fused
Reasons:1. There are oxide scales and rust in the weld zone.; 2. Insufficient heat input; 3. Welding pool is too big; 4. Low welding technology; 5. unreasonable joint design
Preventive Measures:1. There are oxide scales and rust in the weld zone; 2. Insufficient heat input; 3. Welding pool is too big; 4. Low welding technology; 5. unreasonable joint design
6.Defects:Incomplete penetration
Reasons:1. Incorrect groove processing; 2. Low welding technology; 3. Inappropriate heat input
Preventive Measures:1. Increase groove angle, reduce blunt edge size and increase clearance; 2. Adjusting walking angle; 3. Increase wire feeding speed to obtain larger welding current.Maintain proper distance between nozzle and workpiece
7.Defects:spatter
Reasons:1. Too low or too high voltage; 2. Poor cleaning of welding wire and workpiece; 3. Welding wire unevenness; 4. Conductive nozzle wear; 5. Inappropriate welding maneuver characteristics
Preventive Measures:1. Adjust the appropriate voltage according to the current; 2. Cleaning welding wire and workpiece; 3. Check the wire feeding wheel and hose; 4. Renewal of Conductive Nozzle; 5. Adjusting DC inductance
8.Defects:Hunting weld
Reasons:1. Welding wire stretching out too long; 2. Bad adjustment of wire correcting mechanism; 3. Conductive nozzle wear
Preventive Measures:1. Welding wire stretching out too long; 2. Bad adjustment of wire correcting mechanism; 3. Conductive nozzle wear
More information about our Corrugated Transformer Tanks Welding & Transformer Corrugated Fins Wall Folding & Welding Manufacturing, please feel free to contact with us ::+008615195010186 cnkylt@aliyun.com
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