Common problems with steel structures

1、 Blanking:

1. The docking of web and wing plates does not meet the specification requirements (web splicing length ≥ 600mm, wing splicing length ≥ twice the plate width)

2. Uneven cutting edges with large local gaps

3. The cutting size deviation is significant and does not comply with the specification standards (allowable deviation of wing and web width ± 3mm)

4. Insufficient slag cleaning

5. Excessive cutting allowance (allowable allowance for constant cross-section H-shaped steel ± 20mm, allowable allowance for variable cross-section ± 30mm, and no allowance for crane beams)

2、 Assembly

1. Uneven connection at one end of H-shaped steel

2. Excessive gap between web and wing plates

3. The verticality of the wing plate does not meet the standard specifications (allowable deviation for verticality: wing plate width b ÷ 100, and not more than 3mm)

4. The eccentricity of the web plate does not meet the standard (allowable deviation of eccentricity is 2mm)

5. The spacing length of positioning welding is different, and the size of welding points is inconsistent

6. Connecting H-shaped steel with section greater than 500mm is not braced

3、 Submerged arc welding

1. Improper operation during lifting and flipping components, resulting in component deformation

2. There are many pores. (No pores allowed)

3. Repair welding, inadequate polishing, poor polishing appearance, not smooth, and most of the excavation and grinding

4. Inconsistent size of welding legs and deviation of welding beads

4、 Accessory

1. The auxiliary parts were not drilled according to the drawings, mainly consisting of supporting plates with different specifications

2. Poor cutting appearance (the cutting angle of the ear plate should use arc angle)

3. The specifications of the triangle plate are inconsistent

4. When placing components, they are not neatly stacked and not classified according to each item

5、 Correction

1. Lifting more than 2 components with a single hook at a time

2. Forcibly using a crane to lift components during correction, resulting in deformation of the components

3. The verticality of the wing plate does not meet the standard specifications (allowable deviation for verticality: wing plate width b ÷ 100, and not more than 3mm)

4. Web plate deformation

5. The deformation of components caused by the machine, and the operator did not provide timely feedback for warranty

6、 Assembly

1. Inconsistent cutting groove angle, poor appearance, and uncleaned welding slag

2. The angle between the end plate and wing plate does not match the drawing

3. Excessive gap between weld beads, affecting the formation of secondary welding

4. Misuse of components with similar specifications

5. The overall size, diagonal, component size, direction, and verticality of the component do not meet the requirements of the drawing, or the deviation is too large

6. Failure to familiarize oneself with the drawings in a timely manner before assembly often leads to errors, low qualification rates, and even batch errors

7、 Gas shielded welding

1. Do not use support rods when welding large cross-section components

2. Use manual force to forcefully push down large cross-section and long components when flipping over

3. Inconsistent size of welding legs

4. Poor appearance molding: defects such as pores, slag inclusions, arc pits, undercuts, flowing, welding overlap, missed welding, excessive splashing, unevenness, etc

5. The butt weld seam is uneven in height and size, not in a straight line

8、 Improve

1. Lifting components from the gas shielded welding area with a one-time quantity exceeding 6 or exceeding the weight limit

2. Inadequate handling of cutting edges

3. Inadequate cleaning, polishing, and filling of defects, especially the polishing of butt welds

4. Component deformation and inadequate flame correction for side bending

5. Weld gas