(1) Specifications: The specifications for spiral steel bars must be detailed in import/export contracts. Generally, these include the standard grade (type code), nominal diameter, nominal weight (mass), specified length, and the permissible tolerances for these parameters. Chinese standards recommend a series of spiral steel bars with nominal diameters of 8, 10, 12, 16, 20, and 40 mm. Supply lengths are categorized into fixed lengths and multiple lengths. The range of fixed lengths for Chinese-exported deformed steel bars is 6–12 m, whereas for Japanese-produced bars, it is 3.5–10 m.
(2) Appearance Quality:
① Surface quality. Relevant standards stipulate requirements for the surface quality of deformed steel bars, mandating that ends be cut straight and square, and that the surface be free from cracks, scabs, folds, and other defects detrimental to usage;
② Permissible dimensional deviations. Relevant standards specify requirements regarding the curvature and geometric shape of the bars. For instance, Chinese standards stipulate that the curvature of straight bars must not exceed 6 mm/m, and the total curvature must not exceed 0.6% of the bar's total length.
