China is one of the largest country which produce concentrated nitric acid in the world. The main structural material is high silicon cast iron pipe. High silicon cast iron in high and low temperature concentrated dilute nitric acid have good corrosion resistance, but the fragility, weight, poor welding performance, difficult operation (to strictly control the heating and cooling rate) and poor thermal conductivity, they have brought great inconvenience to normal production. Yinhuan produced the C4, C5, C8 steel seamless tubes, (equivalent to KY704 / KY705 / KY706,) which have overcome these disadvantages of high silicon cast iron, it has a very broad market space with light weight, easy welding, thermal conductivity.