Each rail welded joint shall be ins

Each rail welded joint shall be inspected by ultrasonic inspection, and the temperature of the welded joint shall not be higher than 40 °C. When the temperature of the welded joint is higher than 40 °c, the surface temperature of the rail head should be lower than 250 °C. When the defect equivalent of the welded joint is greater than the specified value of the flaw detection sensitivity, it should be judged that the welded joint is not qualified, that is, when the following defects are found in the welded joint, it should be rejected: When the double probe is detected, the rail bottom angle is greater than or equal to 3 ~ 6DB flat bottom hole equivalent; The other parts are greater than or equal to 3 equivalent of flat bottom hole, the rail head and rail waist are greater than or equal to 3 equivalent of long horizontal hole, the rail bottom is greater than or equal to 4 equivalent of vertical hole, and the rail bottom angle is greater than or equal to 4ー6 db equivalent of vertical hole The defect equivalent is 3 DB lower than the defect defined by the sensitivity of flaw detection, but the elongation length is more than 6 mm. The flaw detection result must not have the harmful defects such as incomplete welding, over-burning, crack, blowhole, slag inclusion, etc. . Those unqualified in inspection should be sawed and re-welded.