Knowledge of thermit welding operation

Preparation:

When preparing for rail thermit welding, start from the rails on both sides of the weld, loosen 2-4 groups of fasteners on each side, then lock the rail fasteners within 50m at least according to the specifications, and mark the rails at the first locking fastener on both sides of the weld to observe whether the rails move, and then conduct thermit welding.

Rail end drying:

During rail thermit welding, the preheating gun shall be used to heat and dry the rail within 0.5m on both sides of the weld before sand mold installation, so as to fully remove the water on the rail surface.

Derusting and decontamination of rail end:

① Within 50mm from the rail end, install the steel wheel set with an angle grinder, grind and remove the dirt and rust on the end face, rail head, rail waist and rail foot of the welded rail, and then grind with an angle grinder equipped with a grinding wheel. Pay special attention to grinding and cleaning the rail bottom;

② After grinding, the edge of rail head end shall be chamfered 1mm × 45°。

Installation of preheating gun support for rail thermit welding:

② The preheating gun base shall be installed in the upwind direction to avoid flame burning of the preheating system caused by upwind installation;

② Adjust the preheating gun barrel to be parallel to the rail surface;

③ Set the preheating gun height with a multi-purpose feeler gauge, and the preheating gun head height is generally set to 30-40mm。

Control of preheating process of rail thermit welding:

Adjust the gas valve and control the flame shape to keep the length of blue flame core at 15 ~ 20mm Within the range, the flame is neutral at this time