Abstract: Disclosed is a device by which a defective product is removed from a path through which products are continually fed. The device has a feeder feeding products, a sensor detecting defective products, and a remover taking the defective products from the path. The sensor outputs a signal denoting a defect in either the trailing half of a first product or the leading half of an adjacent second product. The remover has a function for obtaining the number which is a quotient obtained by dividing the distance between the sensor and the remover by the length of a normal product. The remover takes out the defective and the adjacent product when the number of products passing the remover is equal to the quotient obtained by the above calculation.

Abstract: A heat exchanger such as a radiator for an automotive engine is produced by fixing lengths of flattened tubes and corrugated fins to each other by brazing within a furnace. The flattened tube is formed by bending a strip and welding the opposing edges of the bent strip to each other to form a tube of a substantially circular cross-section, and applying pressure to the tube along the weld line to form the flattened tube while depressing the tube wall along the weld line to form an elongated recess or groove along the weld line. Then, a brazing material is applied to the outer surfaces of the flattened tube to cover and fill up any minute weld defects which may exist in the flattened tube whereby the weld defects are repaired.