What are the precautions for welding and electric welding operation

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Arc initiation: (1) Scratching method. First align the electrode with the weldment, and then gently scratch the electrode on the surface of the weldment like a match, igniting the arc, and then quickly lift the electrode 2 4mm and make it burn stably.

2) Percussion method. Align the end of the electrode with the weldment, then bend the wrist downward, make the electrode touch the weldment slightly, and then quickly lift the electrode 2 4mm, and then flatten the wrist after igniting the arc, so that the arc remains stable and burning.

Operating Procedures:

Use the welding machine in strict accordance with the data on the nameplate of the welding machine, and shall not be overloaded.

The current should be adjusted in the no-load state, and a long-term short circuit is not allowed when the welding machine is working.

Before using the welding machine, it should be checked that the wiring of the welding machine is correct, the current range meets the requirements, the shell is grounded reliably, and there are no foreign objects in the welding machine before it can be closed.

When working, there should be no strong vibration in the core of the welding machine, and the screws that compress the core should be tightened. The temperature of the welding machine and the current regulator should not exceed 60°C.

Strengthen maintenance work, keep the inside and outside of the welding machine clean, ensure that the welding machine and welding flexible wire are well insulated, and repair it immediately if there is damage or burns.

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It introduces the joint form and groove form of the weldment; as well as commonly used transportation methods; Flat welding, vertical welding, horizontal and vertical welding, pipe welding and other professional knowledge. There are also various precautions.

Specific content includes:

1. Basic concepts and related knowledge of welding.

2. Welding arc, equipment, tools and maintenance.

3. Manual arc welding process.

Fourth, the welding of commonly used metal materials.

5. Welding materials and welding metallurgical foundation.

6. Welding stress deformation and welding defect generation and prevention.

7. Gas welding and gas cutting.

8. Manual tungsten argon arc welding.

9. Welding and cutting safety technology.

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Electric welding is a special operation, and welders must be certified to work; Automatic switches should be used for power control, and manual switches are not allowed; The first and secondary lines must be equipped with anti-electric shock protection devices; The length of the primary line does not exceed 5m, and the floor cannot be mopped; The length of the secondary wire should be less than 30m, the wiring should be crimped firmly, and a protective cover should be installed; The welding tongs should use special cables, double wires in place, no joints, no damage, no insulation; Do not borrow metal scaffolding, track and structural steel bars as circuit ground wires.

The matters that should be paid attention to when welding include the welding speed, the length of the arc, the order to be considered in the selection of welding wire, and the key points of welding wire selection.

1. Welding speed.

The appropriate welding speed is based on the diameter of the welding rod, the type of coating, the welding current, the heat capacity of the welded object, the beginning of the structure and other conditions, and there are corresponding changes, and the standard cannot be stipulated. Maintain the right welding speed, and the slag can cover the molten pool well.

All kinds of impurities and gases in the molten pool have sufficient time to float out, so as to avoid the formation of slag inclusions and porosity of the weld. If the speed of the rod is too fast during welding, the shrinkage stress will increase when the welding part is cooled, causing cracks in the weld.

Second, the length of the arc.

The length of the arc is related to the type of electrode coating and the thickness of the coating. However, short arcs should be taken as much as possible, especially low-hydrogen electrodes. Long arcs can cause stomatosis.

The short arc can avoid harmful gases such as O2 and N2 in the atmosphere from invading the weld metal and forming undesirable impurities such as oxides and affecting the quality of the weld.

Third, the order to be considered in the selection of ruler fluttering ear welding wire.

1. Select the welding wire according to the steel type of the welded structureFor carbon steel and low-alloy high-strength steel, the welding wire that meets the mechanical property requirements is mainly selected according to the principle of "equal strength matching".

2. According to the quality requirements of the welded parts (especially the impact toughness), the selection of welding wire is related to the welding conditions, groove shape, shielding gas mixing ratio and other process conditions, and the welding materials that achieve large welding efficiency and reduce welding costs should be selected under the premise of ensuring the performance of welded joints.

3. Select the diameter of the welding wire according to the on-site welding position corresponding to the thickness of the welded workpiece, determine the current value used, refer to the product introduction information and use experience of each manufacturer, and select the welding wire grade suitable for the welding position and current used.

Fourth, the key points of welding wire selection.

The selection of welding wire should be based on the type of steel to be welded, the quality requirements of the welded parts, the welding construction conditions (plate thickness, groove shape, welding position, welding conditions, post-welding heat treatment and welding operation waiting), cost, etc.

Welders must be equipped with safety equipment such as masks with suitable light filters, dry canvas overalls, gloves, rubber insulation, and white light glasses for slag removal. Prevent burns and fires from splashed metal or red-hot weldments. Prevent the harm of arc light radiation to the human body.

Prevent poisoning by certain harmful gases. When working at height, wear a seat belt and a helmet. When repairing and welding pressure vessels that have been filled with combustible substances, they can only be welded after they are disposed of according to the regulations, and welding accidents should be prevented.

Welding of load-bearing structures without reinforcement measures is not permitted. In welding in a humid environment, necessary measures should be taken to avoid electric shock accidents. In terms of welding operations:

Welding is carried out according to the process requirements of the drawing. The electrode should meet the design requirements and be dried according to the requirements. The form and size of the weld should meet the requirements of the drawings to ensure the quality of welding.

Precautions:

1. In strict accordance with the number of the welding machine nameplate on the mark, Qingfeng uses the welding machine according to the number and shall not be overloaded;

2. Before using the welding machine, check whether the wiring of the welding machine is correct, whether the current range meets the requirements, whether the shell grounding is reliable, and whether there are foreign objects in the welding machine;

3. Regularly check the condition of the circuit of the welding machine and the insulation performance of the bright rock in all parts of the welding machine, and eliminate any problems in time;

4. The welding and cutting operation should be isolated below, and a careful and meticulous inspection should be done after the operation is completed, and the scene can only be left after confirming that there is no fire hazard;

5. Strengthen testing, pay attention to guardianship, and have strict safety organization measures.