In most cases, butt fusion welding is not permitted for conductor steel conduit, nor is casing fusion welding permitted for galvanized steel conduit or thin-walled steel pipe. The thin-walled steel conduit refers to a steel conduit with a wall thickness less than or equal to 2mm, and a thick-walled steel conduit with a wall thickness greater than 2mm.
Reasons why steel conduits are not suitable for butt fusion welded connections:
Taking into account technical and economic reasons, the steel conduit is not suitable for fusion welding butt connection. Technically, fusion welding will cause burn-through and internal nodules, which will damage the insulation layer when threading the cable. Buried in concrete will seep into the slurry and cause the conduit to block. This phenomenon is obviously not allowed to occur; if high-quality welders are used, gas shielded welding method is used, and destructive sampling of welding joints is carried out, which is not necessary for building electrical piping, not only the construction process is cumbersome, and the construction efficiency is low. It's also not economical.
Bendable Metal Conduit and Metal Flexible Conduit:
Bendable metal conduits and metal flexible conduits are determined by their structural characteristics, and the installation and construction process cannot guarantee that the welded conduits will not be damaged, so they are not suitable for fusion welding.
Reasons why galvanized steel conduit is not suitable for butt joint and casing fusion welding connection:
The design uses galvanized materials for the reasons of good corrosion resistance and long service life. The zinc protective layer should not be damaged during construction. The protective layer is not only the outer surface but also the inner wall surface. If fusion welding is used, it will inevitably damage the inner surface. , The zinc protective layer on the outer surface, the outer surface can still be remedied by painting, but the inner surface cannot be painted, which obviously goes against the original intention of using galvanized materials in the design.
Thin Wall Steel Conduit:
Now there are many connection process standards for thin-walled steel conduits, such as threaded connections, tight connections, ferrule connections, etc., which are both technically feasible and economical. The process problem can be solved, this statement only does not allow the application of fusion welding process with too much safety risk.