thick wall big rectangular and square tubes 1. max wall thickness 40mm 2. max OD ... -40 mm, length: 15 meters.\material: Q235B, Q345B, 20#, 16Mn, and alloy material. 2. Rectangular Steel Tubes Min size: 30*40mm ... : 6-40mm, Length: 15 meters.material: Q235B, Q345B, 20#, 16Mn, and alloy material.