Abstract: The paper involves a discussion about the basic elements responsible for steel tube geometric accuracy and the on-line gamma ray NDD inspection and control technique for steel tube O. D. and W. T. developed abroad in the recent years. Comparisions are made between different steel tube manufacture processes in terms of W. T. control chracteristics. No matter what kind ofProcess is employed,it is possible to improve geometric accuracy of the tube by means of optimized die design and process schedule