Process requirements and quality control points for the manufacture and installation of cold-rolled steel plate air ducts

1. Process requirements

1) The outer diameter or outer length of the air duct shall prevail, and shall be welded;

2) The weld seam of the welded air duct should be flat, and there should be no cracks, protrusions, penetrating slag inclusions, air holes and other defects. The deformation of the plate after welding should be corrected, and the welding slag and spatter should be removed;

3) The surface of the air duct should be flat, and the unevenness should not be greater than 8mm;

4) The allowable deviation of the outer diameter or the length of the outer side of the air duct is a negative deviation. When the length of the large side of the air duct is less than or equal to 630mm, it is -1mm; when it is greater than 630mm, it is -2mm;

5) The allowable deviation of the flatness of the nozzle is 1mm, and the difference between the lengths of the two diagonals of the rectangular duct should not be greater than 2mm;

6) Reinforcement measures should be taken for rectangular air ducts with a side length greater than 630mm, thermal insulation ducts with a side length greater than 800mm, pipe section lengths greater than 1250mm, or low-pressure air ducts with a single side area greater than 1.2㎡, and medium and high-pressure air ducts greater than 1.0㎡;

7) The inner and outer surfaces of ordinary thin steel air ducts without heat preservation are coated with red lead antirust paint twice, and the outer surface is coated with topcoat twice. For the smoke exhaust duct, after the red lead antirust primer is applied, the inner and outer surfaces are coated with heat-resistant paint twice. . The color of the finish paint is black if there is no special requirement for the decoration profession; for the air duct with heat preservation, the inner and outer surfaces of the heat preservation should be coated with anti-rust primer twice.

2. Key points of quality control

1) It is strictly forbidden to have defects such as burn-through, missing welding and cracks in the weld seam of the air duct, and the longitudinal weld seam must be staggered, and there must be no cross-shaped seam;

2) When the air duct and the flange are connected by welding, the end face of the air duct shall not be higher than the plane of the flange interface; when the connection is fixed by spot welding, the solder joints shall be well fused, and the distance shall not be greater than 100mm;

3) The flange and the air duct should be close to each other, and there should be no gaps or holes that penetrate.

4) During the anti-corrosion treatment of the air duct, the next anti-corrosion treatment should be carried out after each paint is dried;

5) It is strictly forbidden for unlicensed personnel to work on the job;

3. Finished product protection measures

1) The semi-finished and finished products of the air duct must be neatly placed on the square wood, and each layer should not exceed 1.2m. Multi-layer stacking is strictly prohibited to cause deformation of the air duct;

2) Do not mix with other materials, equipment, etc., and have measures to prevent rain and snow;

3) When the finished air duct is stacked for a long time, it should be covered with plastic film to keep the surface of the steel plate clean and avoid dust accumulation;

4) When stacking, it should be numbered according to the system, neat and reasonable, and easy to ship;

5) Handling and loading and unloading should be handled with care to prevent damage to the finished product.

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