... 3. Material: ASTM A53,A106,A210,A283;ST33, ST37,ST52;S235, S355 etc A very specialized rectangular pipe & square pipemanufacturer in China ... with more than 9 years history and an annual output over ... ASTM A210,ASTM A283,ST33, ST37-2,ST52, DIN1626,DIN1629,STPY41,G3452,G3457, S235,S355, Q195-Q235,Q345,20#, alloy steel etc7 ...