为了保证生产和生活的需要，需要在不拆保冷层的条件下对LNG(液化天然气)管道剩余壁厚进行在役检测。以LNG保冷管道为例，分析了切向射线检测技术的基本原理，并用所开发的切向射线检测试验装置对一段LNG管道进行了检测试验，然后对其检测精度与千分尺测量结果进行了对比分析，最后对某条在役LNG管道进行了剩余壁厚检测，并结合Gumbel极值分布方法预测了整条LNG管道的最小剩余壁厚。试验结果表明，切向射线检测方法可以有效地对带保冷层LNG管道壁厚进行检测，可以预测整条LNG管道的最小剩余壁厚，且LNG管道的最小剩余壁厚符合Gumbel极值分布。

In order to ensure the needs of production and life, LNG (liquefied natural gas) pipelines need to be in-service inspected of the remaining wall thickness of the pipeline without removing the cold insulation layer. Taking the LNG cold preservation pipeline as an example, the article analyzes the basic principles of tangential ray detection technology, and uses the developed tangential ray detection test device to test a section of LNG pipeline, and then compares its detection accuracy with the micrometer measurement results. Following the analysis, the remaining wall thickness of an in-service LNG pipeline was tested and combined with the Gumbel extreme value distribution method to predict the minimum remaining wall thickness of the entire LNG pipeline. The test results show that the tangential ray detection method can be effectively applied to the wall thickness detection of LNG pipelines with cold insulation and can predict the minimum remaining wall of the entire LNG pipeline, and the minimum remaining wall thickness of the LNG pipeline conforms to the Gumbel extreme value distribution.