1. Precautions for Operating a Welding Machine
1. Before use, check and ensure the correct connection of the primary and secondary electrode wires, and that the input voltage complies with the specifications on the welding machine’s nameplate. After turning on the power, strictly avoid contact with live parts of the primary circuit.
2. The secondary tapping connections to the copper plate should be securely tightened, and the terminal posts should have washers. Before closing the circuit, thoroughly inspect the connection nuts, bolts, and other components.
3. When multiple welding machines are used together, they should be connected to a three-phase power supply network to achieve balanced three-phase loads. The grounding devices of each welding machine should have separate connections and must not be connected in series.
4. When moving the welding machine, disconnect the power supply and do not drag the machine using the welding cables.
5. During field operations, the welding machine should be placed in a sheltered area with good ventilation.
6. It is not allowed to use iron plates instead of the welding machine’s work clamp during welding.
7. The welding machine’s casing must have proper grounding and zero protection, and any dismantling or installation of other power sources should be carried out by an electrician. The insulation resistance between the primary and secondary windings of the welding machine, between the windings and the iron core, and between the windings, leads, and the casing must not be less than 0.5 megohms.
8. The welding machine should be placed in a rainproof and well-ventilated area. Flammable and explosive materials are prohibited from being stored at the welding site, and protective equipment must be worn for spot welding.
9. The length of the primary power cable for AC arc welding machines should not exceed 5 meters, and the length of the secondary cable should not exceed 30 meters.
10. The welding clamp and electrode holder must have good insulation and secure connections. Gloves should be worn when replacing welding rods. When working in damp areas, stand on insulating rubber or wooden boards.
11. Welding on pressurized containers or pipelines is strictly prohibited. Welding equipment that is energized must be disconnected from the power source first.
12. The welding work area should be equipped with light shielding to prevent arc light from harming people’s eyes. Flammable and explosive materials are not allowed to be stored within 5 meters of the work area. Oxygen cylinders are not allowed to be stored within 10 meters.
13. Hot workpieces after welding or cutting are not allowed to be placed on electrical wires, oxygen rubber hoses, or safety passages. They should be placed in designated or safe areas. When moving the welding machine, it is not allowed to bundle the cables with hands or other wires.
14. The welding machine must have reliable grounding and zero lines. The welding return cable must not be placed on flammable or explosive pipes, and the welding clamp and return cable must be in good condition.
2. Operating Procedures for Welding Machine
1. Purpose
Standardize the operation of personnel for welding machines to ensure their safety.
2. Applicable Scope
This procedure applies to the operation of welding machines owned by China Gas (Holdings) Co., Ltd.
3. Operating Guidelines
3.1 Pre-welding Preparation
3.1.1 Check if the power supply voltage matches the rated voltage for welding, ensure all connections of generators and motors are correct, inspect the insulation performance, grounding wire for the casing, reliability and correctness of the welding circuit. The grounding resistance should not be less than 1 MΩ (megohm).
3.1.2 For new or unused welding machines that have been idle for a long time, insulation resistance should be measured before use, and the value should not be lower than 0.5 megohm.
3.1.3 Check the condition of the commutator and brushes.
3.1.4 Ensure there are no flammable or explosive materials within ten meters of the welding area. The welding machine should be placed in a clean, dry, and well-ventilated location.
3.1.5 Connections between the welding machine, cables, and welding tongs should be secured with bolts or nuts.
3.1.6 Properly wear protective equipment, keep gloves and work shoes dry, and ensure the face shield is intact.
3.1.7 Before starting the welding machine, check the position of the Y/Δ starter handle. It should be in the “Y” position during startup and switched to the “Δ” position after starting. The contact of the Y/Δ starter should be reliable without any looseness, and ensure that the rotation direction of the welding machine matches the direction indicated on the machine label.
3.1.8 After the welding machine is started, observe its operation to confirm there are no abnormal sounds before preparing for welding.
3.2 Safety Operations During Welding
3.2.1 Before striking an arc, give a warning to the personnel present to avoid arc flash injuries.
3.2.2 When turning on the power switch, push it into position once, then switch on the welding machine. When shutting down, turn off the welding machine first, then the power switch. When moving the welding machine, it should be shut down and disconnected from power first.
3.2.3 When changing the work site or moving the cables, cut off the power and avoid climbing ladders while holding the cables.
3.2.4 In the event of a sudden power failure during welding, immediately shut down the welding machine. Do not throw the welding rod randomly; place it in the designated safe location.
3.2.5 Adjustment of Welding Current:
3.2.5.1 The adjustment of welding current includes coarse adjustment and fine adjustment. The current ranges are 50-150 amperes and 120-375 amperes, respectively. They can be uniformly and precisely adjusted by rotating the handwheel and moving the brush position.
3.2.5.2 Based on the diameter of the welding rod and the required welding current, use the coarse adjustment switch to select the coarse adjustment of welding current. Then, rotate the handwheel to the desired welding current position for a trial weld. After the trial weld, fine-tune the handwheel position based on the welder’s personal experience to achieve optimal welding current.
3.2.6 During operation, pay attention to inspecting the welding machine and regulator. If the temperature exceeds 60°C, it should be cooled down.
3.2.7 In case of malfunctions, wire damage, or repeated fuse burnouts, stop the machine for maintenance or replacement.
3.2.8 The secondary voltage during welding should not deviate from 60-80 volts.
3.2.9 During use, if any abnormalities are found with the commutator, brushes, brush mechanism, or rolling bearings, stop the machine immediately for inspection. Under normal operating conditions, regularly inspect and maintain the cleanliness and replacement of the commutator and brushes.
3.3 Post-Welding Operation
3.3.1 After completing welding work, cut off the welding machine’s power supply and organize the cable and flexible wire. Move the welding machine to a safe location or cover it to protect it from rainwater.
3.3.2 Thoroughly inspect and clean the construction site, and only leave after confirming there are no hidden hazards.
3.4 Other Safety Precautions
3.4.1 Only personnel with operating certificates are allowed to operate the welding machine.
3.4.2 It is strictly prohibited to connect to lighting sockets or circuits. Wiring should be done below the corresponding capacity-matching switch.
3.4.3 Generally, it is not allowed to connect with other wires in parallel, as this often leads to switch burnout due to failure to tighten the screws during dismantling.
3.4.4 Welding is strictly prohibited in areas with high dust levels or volatile chemicals to prevent accidents.
3.4.5 When working in damp areas, wear insulated rubber boots or take other insulation measures.
3.4.6 In poorly ventilated environments where harmful gases are not easily exhausted, forced ventilation measures should be taken.
3.4.7 When welding in small pits or poorly ventilated trenches, there must be someone supervising.
3.4.8 When welding at the joint of a gas pipeline or repairing pipelines and equipment, safety measures must be developed and approved by the competent authority. A dedicated safety officer must be present for supervision before welding can be carried out.
3.4.9 When welding in flammable, explosive, or hazardous areas, approval must be obtained from the relevant authorities, and effective preventive measures should be taken.
3.4.10 When welding non-ferrous metals or objects coated with oil, the working area should have good ventilation, and personnel should position themselves upwind.
3.4.11 If the welding machine is not used for a long period, it should be stored in a dry and well-ventilated place with a relative humidity not exceeding 85%, a temperature not exceeding 40°C, and not lower than 0°C. The commutator should be wrapped in oil paper, and the non-painted non-conductive parts should be coated with grease.
