1. When using the acoustic emission method, it should be remembered that each tested object has its own unique properties. To ensure greater reliability of the data obtained at the testing at each site, it is necessary to carry out measurements of the propagation velocity of waves, the attenuation coefficient, and take into account other properties characteristic of the object.
2. Selecting a frequency filter is one of the most important decisions when setting up an acoustic emission system. Filters used in systems:
- 30 - 500 kHz - universal for all tasks;
- 30 - 100 kHz - for leak monitoring;
- 100 - 300 (400) kHz - for testing welded joints and the base metal of steel structures.
3. Selection of time parameters
- Hit definition time SCETO:
- 500 μs for vessels and tank walls;
- 1000 μs - for process pipelines;
- 2000 μs - for main pipelines;
- Dead Time - half of SCETO.
- Max. Duration is always 65535 μs.
4. An important parameter when tuning in an object is the propagation velocity of waves in the object. The velocity depends on the material of the object, its filling, insulation, thickness, type of AE sensor, operating frequency band, threshold, distance between the sensors, etc. When monitoring and adjusting the location, it is very important to make preliminary measurements of the wave propagation velocity. This operation is provided by the software and can be read in detail in the manual. In practice, the following approximate velocity values are obtained:
- about 3000 m / s for vessels and pipelines with gas;
- about 5000 m / s for vessels and pipelines with liquid for a wave in a wall less than 50 mm thick;
- about 2900 m / s for vessels and pipelines with liquid for a wave in a wall thicker than 50 mm;
- about 1400 m / s for a wave of water in the pipeline;
- about 1200 m / s for a wave of oil in the pipeline.