API 5L SSAW Welded Large Diameter Spiral Steel tube

　　The 16Mn including Q345A, Q345B, Q345C, Q345D, Q345E this is the distinction between the quality level, from A to E in turn increased, mainly due to phosphorus and sulfur and other micro-element content of the impact of different temperature difference, The chemical composition of different mechanical properties.

　　API 5L SSAW Welded Large Diameter Spiral Steel tube of a material. Q represents the yield of this material, the back of the 345, is the yield value of this material, in 345 or so. And the yield value decreases as the thickness of the material increases.