... . Material: ASTM A53,A106,A210,A283;ST33, ST37,ST52;S235, S355 etc A very specialized rectangular pipe & square pipemanufacturer in China ... ,ST33, ST37-2,ST52, DIN1626,DIN1629,STPY41,G3452,G3457, S235,S355, Q195-Q235,Q345,20#, alloy steel etc7. Technology:Seamless; Or ...