The external execution standard of straight seam steel pipe of q345 is: gb709, and the internal execution standard is: gb/t1591-94. Due to the execution standard, such steel plate is allowed to be delivered with negative tolerance. The latest implementation standard is GB/T1591-2008.
Another: Q345 straight seam steel pipe latest standard GB/T1591-2008 Compared with the old standard, one of the most obvious changes is the change of Mn element content, corrected from the original 1.0-1.60 to ≤ 1.70, eliminating the minimum value of the limit.
With the discovery of modern industry, the continuous progress of science and technology, the application of various trace elements in steel plate is also more extensive, Mn content is no longer the only factor affecting the strength and mechanical properties of steel. Therefore, the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China and the China National Standardization Administration jointly issued and implemented the standard for low-alloy high-strength structural steel, eliminating the limit of Mn content interval and only specifying the maximum value.
For Q345 straight seam steel pipe steel testing, on the one hand, whether the elemental content of steel to meet the national standard requirements, the most important aspect is to test the mechanical properties of steel through professional institutions (yield strength, tensile Q345B steel pipe Q345A grade, is not to do impact; Q345B grade, is 20 degrees room temperature impact; Q345C grade, is 0 degrees impact; Q345D grade, is -20 degrees impact; Q345E grade, is -40 degrees impact. At different impact temperatures, the impact values are different. Q345A, Q345B, Q345C, Q345D, Q345E. This is the distinction of grade, which represents, mainly the impact temperature is different and carry on! decreases. Longitudinal steel pipe is a steel pipe with welded seams parallel to the longitudinal direction of the pipe. It is usually divided into metric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on. Longitudinal welded pipe production process is simple, high production efficiency, low cost, the development of faster. The strength of spiral welded pipe is generally higher than the straight seam welded pipe, can use a narrower billet to produce a larger diameter of welded pipe, but also the same width of the billet to produce a different diameter of welded pipe. But compared with the same length of straight seam pipe, the weld length increases by 30~100%, and the production speed is lower. (Test) whether the standard is met.