保温层下腐蚀是压力管道中经常发生且难以避免的一种损伤，脉冲涡流和超声导波等方法对该损伤的检测精度较低，无法满足管道定期精确测厚的要求。采用数字射线边界法对带保温层管道的壁厚进行检测，对检测误差进行了理论分析。结果表明，数字射线边界法检测精度较高，可用于工程实际。

Corrosion under the insulation layer is a kind of damage that often occurs and is difficult to be avoided in pressure pipeline. The detection accuracy of pulse eddy current and ultrasonic guided wave is low, which can not meet the requirements of regular and accurate thickness measurement of pipeline. The digital ray boundary method is used to measure the wall thickness of insulated pipeline, and the measurement error is analyzed theoretically. The results show that the digital ray boundary method has high detection accuracy and can be used in engineering practice.