Standard For Rail Damage

1. The wear of the rail head exceeds one of the listed limits.

2. The length of rust penetration on the lower jaw of the rail head shall not exceed 30mm.

3. Lowering of steel rails (including tread pressure and wear at the rail end): Lines with allowable speeds exceeding 160km/h exceed 1mm, lines with allowable speeds exceeding 120km/h exceed 1.5mm, and other lines exceed 3mm.

4. There are peeling off blocks on the rail end, rail top surface, quenching layer or welding repair layer, with a length exceeding 15mm. The depth of the line with an allowable speed exceeding 120km/h exceeds 3mm, and the depth of other lines exceeds 4mm.

5. Scratches on the top surface of the steel rail, with a depth of 0.5-1.0mm for lines with allowable speeds greater than 120km/h, 1-2mm for other lines, and a wavy wear valley depth exceeding 0.3mm for lines with allowable speeds greater than 120km/h, and 0.5mm for other lines:

6. Steel rails that are deemed damaged by rail inspection personnel or track maintenance workers.

1. The wear of the rail head exceeds one of the listed limits.

2. The steel rail has cracks in any part (but welding cracks should be determined after identification).

3. The length of rust penetration on the lower jaw of the rail head exceeds 30mm.

4. Lowering of steel rails (including rail end tread pressure and wear): For lines with a permissible speed exceeding 160km/h, the permissible speed exceeds 1.5mm; for lines with a permissible speed exceeding 120km/h, the permissible speed exceeds 2.5mm; and for other lines, the permissible speed exceeds 3.5mm.

5. The rail end, rail top surface, quenching layer or welding repair layer have peeling off blocks. For lines with a permissible speed exceeding 120km/h, the length exceeds 25mm and the depth exceeds 3mm. For other lines, the length exceeds 30mm and the depth exceeds 8mm.

6. Scratches on the top surface of the steel rail, with a permissible speed greater than 120km/h on tracks and a depth of 1-2mm, and exceeding 2mm on other tracks.

7. If the steel rail deforms in any part (such as widening of the rail head, twisting of the rail waist, or bulging), it is confirmed through judgment that there are hidden cracks inside.

8. After removing rust from the steel rails, for lines with a permissible speed greater than 120km/h, the thickness of the rail base should be less than 8mm (measured at the edge of the rail base) or the thickness of the rail waist should be less than 14mm. For other lines, the thickness of the rail base should be less than 5ram (measured at the edge of the rail base) or the thickness of the rail waist should be less than 8mm.

9. Other defects (including black and white nuclei) that are believed by rail inspection personnel or track maintenance foremen to affect driving safety.

According to the railway industry standard BT/T1632-91 "Technical Conditions for Rail Welding Joints":

1. The rail welding head shall not have harmful defects such as incomplete penetration, overburning, cracks, porosity, slag inclusion, etc.

2. A small amount of gray spots are allowed on the fracture surface of the rail welding head. The area of a single gray spot shall not exceed 10mm ². The total area of gray spots shall not exceed 20mm ². When the distance between adjacent gray spots is smaller than the size of the smaller gray spot, the middle area is merged with the two gray spots to calculate the area. If gray spots appear, the gray spot area should be doubled for calculation.

3. A small amount of light spots are allowed on the fracture surface of the pressure welding head except for the rail bottom angle. For now, the maximum area of a single light spot is 8mm ², and there is no limit to the number of light spots, but the total area must not exceed 50mm ². If a light spot appears, the area of the light spot should be doubled for calculation.

The above standards 2 and 3 are the allowable defect areas on the fracture surface of drop hammer, static bending or fatigue specimens in welding tests. In ultrasonic testing, most defects found under general sensitivity conditions are larger than the allowable defect area. Therefore, if defects are found during the non-destructive testing of the rail bottom of the weld seam, they will be judged as serious injuries. The rail head and rail waist can be handled according to the above standards as appropriate.