X射线周向曝光技术因为一次可以完成360°周向曝光，拍片效率高，横向裂纹检出率高，所以在压力容器、锅炉、管道环缝射线检测的应用越来越广泛。但随着焦距增大射线入射强度显著下降，在保证相同曝光量条件下如何选择发射管电压和曝光时间成为大焦距周向射线探伤的难点。以某空分装置两台低温储罐为例介绍了大焦距(F=10 m)周向X射线探伤技术的应用情况。

Circumferential exposure technology of X-ray detection is increasingly applied to pressure vessel, boiler and pipeline radiographic inspection because of its 360°exposure one-time, high exposure efficiency and high crack detection rate. With the increment of focal length of the ray incident, the ray intensity decreased significantly. When it is under the same exposure conditions, how to choose the X-ray tube voltage and exposure time becomes a difficulty of the long focal distance circumferential exposure technology. In this paper, the application of the long focal distance(F=10 m) circumferential exposure technology in two low-temperature storage tanks was introduced as an example.