Keep these winter welding precautions in mind!

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Once winter sets in, the ambient temperature is low; without appropriate protective measures when welding steel components, this can have a significant impact on the quality of the welds. Welding at low temperatures can make the steel more brittle, and it also accelerates the cooling rate of the weld zone and the heat-affected area of the base metal, facilitating the formation of hardened structures and increasing brittleness. This poses a significant risk to the welding of low-alloy steels, which are commonly used in building steel structures. Therefore, welding work in winter must be carried out strictly in accordance with the process requirements; blind welding is not allowed. 01 Welding material requirements: Strict management of the welding material inventory is required; electrodes must be dried in accordance with standards, the number of drying cycles shall not exceed 2, and the exposure time to air shall not exceed 2 hours. If there is no oven on site, an application must be made promptly to obtain one, and a dedicated person should be assigned to carry out the drying process and distribute the items. The welder retrieves the welding rods from the insulated container; the amount taken at one time shall not exceed what is needed for half a day’s work ； During the welding process, the insulation tank lid must be kept closed, and the tank must remain powered on ； Only 1 rod can be used at a time during tack welding ； No more than 3 pieces should be taken at a time during welding. It is strictly prohibited for welding materials to be exposed to moisture; if moisture is detected on the welding materials, they must not be used again. If the welding wire is not used up within four hours, it should be returned to the primary storage area for welding materials; it must not remain on the wire feed reel. For gas shielded welding, the carbon dioxide used should have a purity of not less than 99.9% (on a volume basis), with a water content of no more than 0.005% (on a weight basis). When using gas in a new bottle, it must be inverted for 24 hours before the valve is opened to drain all the water, in order to prevent freezing. Use should be stopped when the pressure of the gas inside the bottle is below 1 MPa. Before welding, check the reading on the gas pressure gauge, then check the gas flow meter and adjust the gas flow. When in use, the bottle opening must be connected to a heating device. Gas cylinders must be stored in an environment with a temperature above 0°C. When using bottled gas, use should be stopped when the gas pressure inside the bottle falls below 1 N/mm2. When using it below zero degrees, check whether the nozzle is blocked by ice. 02 General pre-welding requirements: Remove water, scale, rust, and oil from the surface of the steel to be welded. The relative humidity in the welding area shall not exceed 90%. When the surface of the welded parts is wet or covered with ice and snow, heating measures should be taken to remove moisture. At both ends of the main welds of T-joints, cross joints, corner joints, and butt joints, arc starting plates and lead plates must be used; their material should be the same as that of the base metal to be welded, and the groove shape should be identical to that of the weld to be formed. It is prohibited to use materials of other types as arc starting plates and lead plates. The lead length of welds in manual arc welding and gas shielded arc welding should be greater than 25 mm. The width of its arc-starting plate and lead-out plate should be greater than 50 mm; the length should be 1.5 times the thickness of the plate and not less than 30 mm, while the thickness should be not less than 6 mm ； The lead length of welds in non-glass shielded arc welding should be greater than 80 mm. The width of its arc-starting plate and lead-out plate should be greater than 80 mm; the length should be twice the thickness of the plate and not less than 100 mm, while the thickness should be not less than 10 mm. After welding is completed, the arc starting plate and the lead-out plate should be removed using flame cutting, and then polished smooth. Do not use a hammer to knock down the arc starting plate and the lead-out plate. 03 Welding measures in winter ① Install a shelter: When working outdoors and the ambient temperature is below -5°C, it is necessary to set up a shelter in the welding area to raise the temperature there and protect it from wind and rain. ②Preheating before welding: The weld area should be preheated prior to welding. The preheating zone should be located on both sides of the welding groove; if necessary, a method that involves simultaneous preheating can be used to ensure the appropriate preheating temperature and interpass temperature. The heating temperature is 80~150°C, and the preheating zone extends 1.5t (where t is the plate thickness) on each side of the weld, with a minimum width of 100 mm. Infrared thermometers are used for temperature measurement, with the measurement points located 75 mm from the edge of the groove, on two lines parallel to the center of the weld. ③Welding speed and weld bead arrangement: For manual arc welding in the flat, horizontal, and vertical positions, the welding speed is determined by the specified length of weld to be produced per electrode ； In gas shielded welding, swaying is not allowed for single-pass welding; the thickness of the weld layer should be controlled between 5 and 6 mm, and the angle between the electrode (torch) and the workpiece must be at least 30°. Maximum swing width allowed for vertical welding: 15mm–20mm. ⑥Post-weld slow cooling: After welding thick steel plates at temperatures below zero, heating and cooling measures should be taken within a range of 2 to 3 times the plate thickness on both sides of the weld, to allow the weld to cool slowly; the cooling rate should not exceed 10°C/min.