The materials of spiral steel pipes are: Q235A, Q235B, 20 #, Q345 (16Mn), L245 (B), L290 (X42), L320 (X46), L360 (X52), L390 (X56), L415 (X60), L450 (X65), L485 (X70), L555 (X80), L290NB / MB (X42N / M), L360NB / MB (X52N / M), L390NB / MB (X56N / M), L415NB / MB (X60N / M), L450MB (X65), L485MB (X70), L555MB (X80).

       Q235B is composed of Q + number + quality grade symbol + deoxygenation method symbol. Its steel number is preceded by "Q", which represents the yield point of the steel, and the numbers behind it indicate the yield point value. The unit is MPa. For example, Q235 means carbon structural steel with a yield point (σs) of 235 MPa.

       Q345 is a steel material. It is low alloy steel, "Q" means yield strength, Q345 means that the yield strength of this steel is 345MPa. Q345 will decrease its yield value as the thickness of the material increases. And the domestic production may be less than 345, so the strength must be less than 345 during mechanical design, otherwise there will be problems.