16Mn无缝钢管按照生产牌号可以划分为五个等级；具体分为Q345A/Q345B/Q345C/Q345D/Q345E；
牌号 C碳 Si硅 Mn锰 P磷 S硫 V钒 Nb铌 Al Ti钛 尊龙国际
Q345A 0.20 ≤0.55 ≤1.70 ≤0.045 ≤0.045 0.02-0.15 0.015-0.060 - 0.02-0.20
Q345B ≤0.20 ≤0.55 ≤1.70 ≤0.040 0.040 0.02-0.15 0.015-0.060 - 0.02-0.20
Q345C ≤0.20 ≤0.55 ≤1.70 ≤0.035 ≤0.035 0.02-0.15 0.015-0.060 ≥0.015 0.02-0.20
Q345D 0.18 ≤0.55 ≤1.80 ≤0.030 ≤0.030 0.02-0.15 0.015-0.060 ≥0.015 0.02-0.20
Q345E ≤0.18 ≤0.55 ≤1.80 ≤0.025 ≤0.025 0.02-0.15 0.015-0.060 ≥0.015 0.02-0.20