When the steel structure is constructed in winter, the winter construction plan should be formulated according to the requirements of the winter construction of the steel structure, and the corresponding requirements should be adopted for the use of materials and personnel.
1.due to the influence of the thermal expansion and contraction performance of the material during winter construction, the construction should fully consider the reduction of the component caused by temperature, and adopt the method of adjusting the deviation in the construction. It is better to reserve a shortening margin when the component is fed, and the amount of welding shortening and compression deformation should be coordinated with the amount of shortening deformation occurring below zero degrees Celsius of the steel.
2. The electrode used at negative temperature shall not be exposed for more than 2 hours, and shall be re-baked for more than 2 hours, and the number of baking of the electrode shall not exceed 3 times.
3.when the ambient temperature is below 0 ° C, the coating used in the steel structure shall not be water-based coating, and the coating process test shall be carried out before the coating anticorrosive coating, and the rust, oil, burr and other things on the surface of the component must be cleaned up when the coating is applied, and the appearance must be dry. Do not paint on snowy days or when there is thin ice on the structure.
4. When assembling components, the rust, burrs, soil, oil, snow and other debris remaining in the joint 50mm should be removed, and the joint should be dry and no residual moisture.
5.below zero degrees Celsius for more than 9mm steel plate welding should be selected multi-layer welding, weld from the bottom up layer by layer welding, each weld once welded, such as welding interruption, before welding again to remove welding defects. It is strictly forbidden to initiate arc on the welded base material.
6.steel structure field installation, such as snow or wind speed above 6m/s, set up a protective shed.
7. the winter transport, stacking steel structure to adopt non-slip methods, component stacking site is smooth and solid without puddles, the ground without ice. When the same type of component is stacked, the component should adhere to the level, the pad iron is placed on the same straight line, and the component is prevented from slipping.
8. When the high-strength bolt joint device is installed, the conflict surface of the component shall not have snow and ice, and shall not contact the dirt, oil and other stolen goods.
9. winter welding, pre-welding preheating should expand the heating range to 2 times the plate thickness (1.5 times the plate thickness at room temperature); The heating method should be preferred to use electric heating method to ensure that the preheating area is heated evenly and avoid local overheating of the base metal. Preheat with 2 ~ 4 gas drying gun baking, preheating area on both sides of the weld, each side width should be greater than 2 times the thickness of the solder, and should not be less than 100 mm. The preheating temperature is measured at 50 mm from the center of the weld with a temperature measuring pen, and the welding operation can be carried out when the specified degree is reached.
10. formulate a reasonable post-heating system, for the plate thickness t < 40 mm to take post-welding emergency thermal insulation and slow cooling measures, for t≥40 mm to take post-welding emergency thermal insulation and slow cooling measures, after the heat temperature of 200~300℃. This measure can slow down the cooling rate of the weld and help diffuse the escape of hydrogen
