thick wall big rectangular and square tubes 1. max wall thickness 40mm 2. max OD ... lenghth 15meters 5. special sized can be ordered1. square Steel Tubes min size: 30*30mm, thickness: 2-6mm, lenghth: ... 15 meters.\material: Q235B, Q345B, 20#, 16Mn, and alloy material. 2. Rectangular Steel Tubes Min size: 30*40mm, thickness: 2-6, ... , Length: 15 meters.material: Q235B, Q345B, 20#, 16Mn, and alloy material.