Acoustic emission: METALogic tests more than 500 LPG tanks for Primagaz
Acoustic emission detects tank degradation
Underground tanks encounter various conditions that can weaken or degrade the tank:
Corrosive elements of the soil;
Mechanical stress on top or around the tank;
The gas pressure in the tank;
According to the Flemish legislation, an integrity test is strictly speaking not mandatory for LPG tanks with a volume of less than 13000 l.
Primagaz nevertheless chooses to test a number of their tanks preventatively every year. They follow the European standard EN 12817 that refers to acoustic emission as a possible requalification method.
A big advantage of acoustic emission is that it detects tank degradation at a very early stage and thus allows timely intervention.
Integrity testing through acoustic emission
Acoustic emission is a NDT (non-destructive testing) technique that we use to localize defects in a material.
First we attach sensors to the tank wall. Then we slightly increase the pressure with a mobile unit in a monitoring truck. Materials, and steel in particular, send out pulses of acoustic waves once they are brought under stress. The acoustic waves are registered by means of a measuring channel consisting of sensors, pre-amplifier, cable and measuring device. Through calculations with 2, 3 or more sensors the source of acoustic emission is localized.
Via post-analysis the found sources are typically classified into different categories according to their criticality. The testing of a tank takes about two hours.
Acoustic emission is suitable not only as an integrity test for tanks but also for:
larger LPG vessels (gas bullets, spheres, storage tanks) according to EN 12819;
gas cylinders for all kinds of gases and liquid;
Acoustic emission: safe, fast, non-invasive and non-destructive
The test is fully compliant to the European standards for the inspection of LPG tanks and is therefore the most ideal way to quickly and safely determine the integrity of an LPG tank.
Acoustic emission is also an NDT (non-destructive technique) test. NDT-tests cause no damage to the original material whatsoever
Last but not least, acoustic emission is non-invasive hence the tank does not need to be empty during the examination and can remain in service.