Abstract: Based on the comparative analyses of the physiochemical properties of the steel plates and the steel tubes as made separately by five domestic steel works,a study is conducted on the physiochemical properties of the Φ1 422 mm×38.5 mm X80 LSAW steel pipes as used for the natural gas pipeline projects of Class Four areas,and thus the property level of the said tubes is systematically mastered.The study result shows the test data of the tube,i.e.,the tube body yield strength:555~674 MPa;tensile strength:625~711 MPa;average impact energy at -10℃:376.4 J;and the average DWTT shear area value at -5℃:91%.All the property indexes of the tube have been up to the applicable technical requirements as specified for the said tube to service in Class Four areas with 12 MPa pressure,which means that the domestic steel tube industry has had the capacity to engage in industrialized massive production of the large-sized,ultra heavy-wall LSAW pipe.