DOT pressures vessels (tubes) require periodic inspections to evaluate the integrity and safety of each vessel. After years of use over land and sea, it is important that authorized holders of Requalification Identification Numbers (RIN) conduct a thorough examination of each vessel. There are several non-destructive test methods used for requalification, including hydrostatic (volumetric expansion), ultrasonic, and acoustic emission testing.
Acoustic emission testing (AET) is a unique method that offers several advantages to equipment operators. For example, the equipment required for AET is relatively small and can be shipped directly to the location of a trailer or skid container (MEGC). No other method allows for such portable testing of tubes. Unlike hydrostatic testing, acoustic emission testing does not introduce water or other contaminants into the vessel during a test.
When disassembly is not required to examine neck threads, the test procedure allows for AET to occur with the unit assembled. A unit can come directly from service to a test center and be tested within a few hours. For trailers in certain gas services, the unit can be tested with the same gas it is in service for. When a unit only requires AET, the scope of work and time required for inspection is minimal, thus keeping the cost down.
When disassembly is not required to examine neck threads, the test procedure allows for AET to occur with the unit assembled. A unit can come directly from service to a test center and be tested within a few hours.
AET has been used on pressure vessels for over 30 years without incident and complies with requalification requirements of the US Department of Transportation (DOT). AET is also recognized by ISO and CGA standards and other national regulatory bodies.
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