The 'panel splicing'  process in steel structure production is a crucial step in assembling steel plates into components of the required dimensions through splicing and welding. Because steel plates from steel mills are often limited in length and width, they cannot directly meet the cutting dimensions of large H-beams, box columns, and other components. Therefore, flange plates and web plates must be butt-welded in the workshop to form a complete base material. The quality of panel splicing directly affects the overall strength, installation accuracy, and structural safety of the components, making it one of the core processes that must be strictly controlled in steel structure fabrication.

Panel Splicing Types

In steel structure panel splicing, there are mainly two types: flange plate splicing and web plate splicing. Since there are two load-bearing fillet welds at the connection between the flange plate and the web plate, specifications require that longitudinal splicing seams are not allowed for flange plates; splicing is only permitted along the length direction. Web plates, however, can be spliced in both length and width directions, and the splicing seams can be cross-shaped or T-shaped depending on the panel arrangement requirements. Clearly understanding the different splicing rules for these two types of components is a prerequisite for reasonable panel arrangement and avoiding stress concentration.

 Panel Splicing Operations

Plate assembly primarily utilizes submerged arc welding for efficient butt jointing. Before welding, oil, rust, and other impurities must be thoroughly cleaned from the bevel and the area within 30mm on both sides to ensure that the assembly gap and bevel dimensions meet process specifications. Simultaneously, appropriate welding current, arc voltage, and welding speed are selected based on the plate thickness. For medium-thick plates, a hybrid process is often used, employing CO₂ gas shielded welding for the root pass, submerged arc welding for the fill pass on the front side, and high-current submerged arc welding for the final weld bead to ensure full penetration and good weld formation.

 Key Points for Plate Assembly

There are three key points to consider when assembling panels:

First, control the position of the splice joints. The splice joints of the flanges and webs should be staggered by more than 200mm to avoid weld intersections and concentrations.

Second, control welding deformation. During assembly, use clamps to firmly hold the steel plates in place, and employ symmetrical segmented welding or skip welding in sequence. Long components also require leveling with a guideline.

Third, allowance should be made for welding shrinkage during layout. Typically, 20-30mm of shrinkage should be allowed for each weld, and 2-3mm for cut seams, to ensure that the final component dimensions meet design requirements.

1. For steel plates ≤16mm thick, no beveling is required; direct submerged arc welding is used.

For plates >16mm thick, beveling is required; gas shielded welding is used for the root pass, by submerged arc welding for the fill and cover passes.

2. Install an arc-starting and extinguishing plate. The weldability should be no less than that of the base metal. The beveling should be the same as that of the base metal, with a length ≥50mm.

3. Preheating should be performed according to the material being welded and the ambient temperature. The minimum preheating temperature for commonly used steels is shown in the table below.

Ambient temperature: -10°C to 0°C, preheat to above 20°C; if the minimum preheating temperature is above 20°C, use the higher preheating temperature.

Scope: Welding area ≥ 2t (t plate thickness) and > 100mm.

Panel Assembly Inspection

After assembly, a rigorous inspection is required. Visual inspection mainly checks for weld reinforcement, undercut, porosity, and surface cracks. During visual inspection, the distance between the eyes and the inspected surface should not exceed 600mm, and the lighting brightness should not be less than 160lx. Internal quality is assessed using ultrasonic testing for non-destructive testing. All Class I and Class II welds must be inspected. Testing operations and defect assessment should comply with GB/T 11345 standards to ensure that the welds are free of defects such as incomplete fusion, incomplete penetration, and cracks.

 Panel assembly is a fundamental process in steel structure fabrication, and its technological level directly determines the starting point for the quality of subsequent assembly and welding. Only through meticulous control at four levels panel arrangement rules, work specifications, process key points, and inspection standards can the load-bearing capacity and service life of steel components be guaranteed from the source, thus building a solid first line of defense for the overall structural safety.

For more information needed or any inquiry,please feel free to contact Yumisteel team.