What Should Be Done Before We Start To Weld？

Welding is a technical operation with certain risks, and sufficient preparation before welding is the key to ensuring welding safety, improving welding quality and efficiency. The following will detail the matters that need to be paid attention to before starting welding from multiple aspects.​
1. Check welding equipment​
The normal operation of welding equipment is the basis for smooth welding work, so a comprehensive inspection of the equipment must be carried out before welding.​
First, check the welding machine. For AC and DC welding machines, check whether the power connection is firm and whether there is any damage to the power cord. If the power cord is cracked or the plug is loose, it may cause electric shock or equipment failure, so it must be replaced or repaired in time. At the same time, check whether the switches, knobs and meters of the welding machine are working normally. For example, the current and voltage adjustment knobs should be able to rotate flexibly, and the meter pointers should be able to return to zero normally to ensure that the parameters can be accurately set during welding.​
Then, check the welding torch and cable. The welding torch is in direct contact with the welding area, and its performance directly affects the welding effect. Check whether the welding torch nozzle is blocked, whether the contact tip is worn or loose. If there is blockage, it should be cleaned in time; if there is wear or looseness, it should be replaced to avoid affecting the arc stability. The welding cable should also be inspected for damage, such as cracks, breaks or aging. If there is any damage, it should be wrapped or replaced to prevent short circuits or electric shocks. In addition, check whether the connection between the cable and the welding machine and the welding torch is firm to avoid poor contact, which may cause excessive heating or arc instability.​
In addition, for equipment that uses shielding gas, such as TIG welding machines, check the gas cylinder. Ensure that the gas cylinder is filled with sufficient shielding gas, and check whether the gas pressure gauge and flowmeter are working normally. At the same time, check the gas pipeline for leaks. You can apply soapy water to the connection parts. If bubbles are generated, it indicates a leak and needs to be tightened or replaced in time to avoid affecting the welding quality due to insufficient shielding gas.​
2. Prepare welding materials​
Welding materials include welding rods, welding wires, base metals, etc., and their quality and state have an important impact on welding quality.​
First, select the appropriate welding materials according to the welding requirements. Different base metals and welding methods require matching welding rods or welding wires. For example, when welding carbon steel, choose carbon steel welding rods; when welding stainless steel, choose stainless steel welding rods. At the same time, the diameter of the welding rod or welding wire should be selected according to the thickness of the base metal and the welding current to ensure that the welding can obtain sufficient penetration and good forming.​
Then, check the quality of the welding materials. Check whether the welding rods are damp, rusted or cracked. Damp welding rods will cause pores, slag inclusion and other defects in the weld, so they need to be dried according to the specified temperature and time before use. For example, low-hydrogen type welding rods usually need to be dried at 350 - 400 °C for 1 - 2 hours. Welding wires should be kept clean, free of oil, rust and other impurities. If there are impurities, they should be cleaned with a wire brush or solvent before use.​
In addition, prepare the base metal. Before welding, the surface of the base metal in the welding area must be cleaned. Remove rust, oil, paint, oxide scale and other impurities with a wire brush, sandpaper or a grinding wheel. This can ensure good fusion between the weld and the base metal and avoid defects such as pores and slag inclusion. For thicker base metals, beveling should be carried out according to the welding requirements to ensure sufficient penetration. At the same time, check whether the base metal has cracks, defects, etc. If there are defects, they should be repaired first.​
3. Ensure the welding environment is safe and suitable​
A safe and suitable welding environment is crucial to the safety of welders and the quality of welding.​
First, check the ventilation of the welding site. Welding will produce harmful gases and fumes, such as carbon monoxide, nitrogen oxides and ozone. If the ventilation is poor, these harmful substances will accumulate, endangering the health of welders. Therefore, the welding site should be well-ventilated. If it is an indoor operation, exhaust fans or ventilation ducts can be installed; if it is an outdoor operation, it should be carried out in a place with good air circulation. In addition, for welding operations that produce a lot of fumes, such as stainless steel welding, a fume extractor can be used to reduce the concentration of fumes.​
Then, check the fire safety of the site. Welding operations are accompanied by open flames and sparks, which are easy to cause fires. Therefore, flammable and explosive materials, such as gasoline, diesel, paint and gas cylinders, must be kept away from the welding site, and the safe distance should generally not be less than 10 meters. At the same time, prepare fire-fighting equipment, such as fire extinguishers, sand buckets, etc., and ensure that they are in good condition and can be used normally. Before welding, clean up flammable substances around the welding site, such as sawdust, cotton yarn, etc.​
In addition, check the lighting and working space of the welding site. Sufficient lighting can ensure that welders can clearly observe the welding pool and the formation of the weld, which is conducive to controlling the welding process. The working space should be spacious enough to facilitate the movement of welders and the placement of equipment and materials. At the same time, keep the site clean and tidy to avoid tripping accidents.​
4. Prepare personal protective equipment​
Welders must wear appropriate personal protective equipment to prevent burns, electric shocks, eye injuries and other hazards.​
First, wear a welding helmet. The welding helmet can protect the eyes and face from arc radiation, sparks and spatter. Choose a helmet with a suitable lens shade. The shade number should be selected according to the welding current. Generally, for low-current welding, a shade 8 - 10 lens is suitable; for high-current welding, a shade 12 - 14 lens is required. At the same time, check whether the helmet is in good condition, such as whether the lens is cracked or blurred.​
Then, wear welding gloves. Welding gloves are made of flame-retardant materials, which can protect hands from high temperatures, sparks and electric shocks. Choose gloves that fit the hand size, ensuring flexibility during operation. Check whether the gloves are worn, damaged or have holes, and replace them in time if any.​
In addition, wear welding clothing. Welding clothing should be made of flame-retardant materials, such as cotton or leather. It can protect the body from burns caused by sparks and spatter. The cuffs and hem of the clothes should be tight to prevent sparks from entering. Do not wear synthetic fiber clothes, because they are easy to melt and burn when exposed to high temperatures, causing more serious burns.​
In addition, wear safety shoes. Safety shoes have anti-smashing and anti-slip functions, which can protect feet from being hit by falling objects and slipping. Choose shoes with steel toes and non-slip soles.​
5. Formulate welding process and conduct pre-welding test​
Before formal welding, it is necessary to formulate a reasonable welding process and conduct a pre-welding test to ensure that the welding parameters and methods are correct.​
First, formulate the welding process. According to the material, thickness, welding position and welding requirements of the base metal, determine the welding method, welding parameters (such as current, voltage, welding speed), welding sequence and other process parameters. For important welding parts, a welding process specification (WPS) should be formulated, which specifies the detailed requirements of the welding process to guide the welding operation.​
Then, conduct a pre-welding test. On the test piece with the same material and thickness as the base metal, perform welding according to the formulated welding process parameters. After welding, check the appearance of the weld, such as whether there are cracks, pores, slag inclusion, undercut and other defects. If necessary, conduct non-destructive testing, such as X-ray testing or ultrasonic testing, to check the internal quality of the weld. If the test results do not meet the requirements, adjust the welding parameters or process methods and re-test until the qualified results are obtained.​
In conclusion, sufficient preparation before welding is essential for ensuring welding safety, quality and efficiency. Only by doing a good job in equipment inspection, material preparation, environmental guarantee, personal protection and process formulation can we lay a solid foundation for smooth welding work.