Spiral steel pipe commonly used classification method
Spiral steel pipe commonly used classification methods are two: First, the geometric shape classification, according to the transverse rib cross-sectional shape and rib spacing different classification or type, such as the British Standard (BS4449), the rebar is divided into ?I type Type II. This classification mainly reflects the grip properties of the rebar. Second, in the performance classification (level), such as China's standard (G?B1499), the rebar is divided into three grades according to the strength level (yield point/tensile strength); Japanese Industrial Standard (JI?SG3112)? According to the comprehensive performance of rebar is divided into five types; British Standard (BS4461), also provides a number of grades of rebar performance test. In addition, rebar can be classified according to its purpose. For example, it can be divided into normal steel for reinforced concrete and heat-treated steel for prestressed concrete.
Specifications and appearance quality
(1) Specifications: The specifications of the spiral steel pipe should be listed in the import and export trade contract. Should generally include standard grades (categories code?), nominal diameters of steel bars, nominal weights (mass), specified lengths, and tolerance values of the above indicators
Items. China's standard recommended nominal diameter of 8,10,12,16,20,40mm spiral steel pipe series. The length of supply is divided into two types, length and size. China's export rebar length selection range of 6 ~ 12m, Japan rebar length range of 3.5 ~ 10m.
(2) Appearance quality: 1 Surface quality. The surface quality of the rebar has been stipulated in the relevant standards. It is required that the end should be cut straight, with no cracks, scabs and folds on the surface, no harmful defects in use, etc.; The requirements for bending and reinforcing bar geometry of rebar are specified in the relevant standards. As stipulated by our country's standards, the straightness bar steel bending is not more than 6mm/m, and the total bending degree is not more than 0.6% of the total bar length.