Seamless steel pipe to ASTM A106, GR.B, in 5.8M length.Sch 404.0 m/tons of 1/2"3.0 m/tons of 1" 2.5 m/tons of 1.1/2" 5.0 m/tons of 2" 4.0 m/tons of 1/2"4.0 m/tons of 1/2"下边的4.0 m/tons of 1/2"是什么意思?是说1/2"的数量是4吨吗?