When welding stainless steel air ducts, pay attention to the following safety matters:

First, welding environment preparation

1. Ensure that the welding site is well ventilated:

- Good ventilation can timely discharge the harmful gases and smoke produced in the welding process, such as ozone, carbon monoxide, metal smoke, etc., to reduce the harm to the welder's body. Install local ventilation equipment or weld in a well-ventilated open space to ensure that the air flow speed is not less than 0.5 meters per second.

- The welding site should be away from flammable and explosive materials, at least 10 meters away from the safety distance, to prevent welding sparks caused by fire or explosion accidents.

2. Clean the area around welding:

- Remove flammable materials such as paper, fabric, plastic, etc. around the welding points. Flammable materials that cannot be removed should be covered with a fireproof cloth.

- Ensure that the floor of the welding area is clean and clean, no water, oil, etc., to prevent the welder from slipping or affecting the stability of the welding operation.

Second, welding equipment inspection

1. Check the welding power supply:

- Before welding, check whether the grounding of the welding power supply is reliable. The grounding resistance should not be greater than 4 ohms. Ensure that the power lines are free from potential hazards such as damage or short circuit. Ensure that the power cables meet the power requirements of the welding equipment.

- Test whether the output current and voltage of the welding power supply are stable, and whether the adjustment knob is flexible and accurate. According to the thickness of stainless steel air duct and welding process requirements, the appropriate welding parameters are set in advance.

2. Check welding tools:

- Check the insulation performance of welding tools such as welding gun, electrode clamp and ground clamp to prevent electric shock. Use insulation resistance tester to test welding tools, insulation resistance should not be less than 1 megohm.

- Ensure that the nozzle and conductive nozzle of the welding gun are not blocked or damaged, and ensure the stability of the welding arc and the gas protection effect. Clean and replace worn parts regularly.

3. Personal Protective Equipment

1. Wear protective clothing:

- Welders should wear welding protective clothing that meets the standards, including fire and heat resistant overalls, work pants and work shoes. Protective clothing should have good insulation and heat insulation properties, can effectively prevent welding sparks and thermal radiation damage to the body.

- Work clothes should be kept clean, free of damage and oil, cuffs and necklines should be fastened to prevent sparks and smoke from entering the inside of the clothes.

2. Wear protective equipment:

- Wear a welding mask or protective glasses to protect your eyes from intense, ultraviolet and infrared radiation from welding arcs. The mask should have good shading performance and clarity, and can automatically adjust the shading degree.

- Wear ear plugs or earmuffs to reduce the damage to hearing caused by welding noise. Welding noise is generally more than 85 decibels, long-term exposure will lead to hearing loss, so effective hearing protection measures must be taken.

- Wear welding gloves, choose high temperature resistance, wear resistance, insulation glove materials, such as cowhide, asbestos, etc. Gloves should be the right size for easy handling of the torch and electrode.

4. Welding operation process

1. Correct arc initiation and extinguishing:

- When starting the arc, the correct arc starting method should be used, such as scratching method or direct hitting method, to avoid random arc starting on the surface of the air duct, to prevent damage to the passivation film on the stainless steel surface and affect the appearance quality of the air duct.

- When quenching, the arc should be slowly pulled to the quenching plate to extinguish, to avoid sudden arc breaking resulting in arc pits and cracks and other defects.

2. Control welding temperature and speed:

- Reasonably control welding temperature and welding speed according to the material and thickness of stainless steel air duct. High welding temperature will lead to coarse grain of stainless steel and reduce the mechanical properties and corrosion resistance of weld. If the welding speed is too fast, it will lead to defects such as non-fusion of the weld and porosity.

- Use equipment such as thermometer to monitor the welding temperature and ensure that the temperature during the welding process is within the appropriate range. According to experience, the interlayer temperature of stainless steel welding should generally be controlled below 150 ° C.

3. Pay attention to welding sequence and method:

- For the welding of large stainless steel air pipes, reasonable welding sequence and methods should be adopted, such as segmented welding, symmetrical welding, etc., to reduce welding deformation and residual stress.

- When welding, the Angle between the welding gun and the air duct surface and the welding speed should be kept uniform to ensure the quality and appearance of the weld. When multi-layer and multi-pass welding is used, the joints of each layer of weld should be staggered to avoid repeated welding in the same position.

5. Post-welding treatment

1. Check weld quality:

- After the welding is completed, the appearance of the weld should be inspected in time to check whether the surface of the weld is smooth and smooth, and whether there are cracks, pores, slag inclusion and other defects. Use weld inspection tools, such as magnifying glass, flaw detector, etc., to test the internal quality of the weld.

- The welding defects found should be repaired in time, and appropriate repair processes and methods should be adopted to ensure that the weld quality meets the requirements.

2. Clean the welding site:

- After the welding work is finished, the debris and residue on the welding site should be cleaned up in time, such as welding rod head, welding wire reel, protective equipment, etc. Keep welding equipment and tools in place.

- Clean and polish the welding area, remove welding slag and splash on the surface of the weld, and make the surface of the air duct smooth and flat. For stainless steel ducts, pickling passivation treatment can also be carried out to restore the corrosion resistance of the stainless steel surface.