An example of weld-joint testing of a new pressure vessel made of stainless steel is considered. The main methods of testing were the method of radiography and the method of acoustic emission. Dangerous defects in the refinery column were detected before running began as a result of the joint application of these methods. This example demonstrates the effectiveness of using such the properties of acoustic emission method, as the integral nature of testing, high sensitivity and the ability to record developing (the most hazardous) defects in the application to the diagnosis of the industrial pressure vessels state. Also, the results of metallographic examination of the specimen of column shell with detected defects are presented. The question of the sequence of application of different methods of non-destructive testing for optimization of the procedure for inspection of large-sized equipment is discussed.