[en] A novel and practical tangential radiography testing method which can be directly applied for internal and external corrosion evaluation of insulated pipes using their external diameters was described. Also , this method can make the task of measuring the pipe's remaining wall thickness much simpler and easier. Application of this method, on especially designed insulated steel pipe of 100 mm diameter, has proved 98 % accuracy in determining the pipe wall thickness and 96 % accuracy in determining the pipe wall thickness reduction at the areas of internal and external machined slots. (author)