A technique has been introduced for the inspection of high-pressure air storage vessels at the Arnold Air Force Base Aerodynamic and Propulsion Test Unit (APTU). This is intended to cut costs and reduce facility downtime.
High-pressure acoustic emissions testing is being used to inspect the large bottles at APTU for cracks, said Adam Fanning, Air Force asset manager for the von Kármán Gas Dynamics Facility. “We haven’t done this at Arnold before, but the inspection technique has been used since the 1970s at other places,” Fanning commented.
The technique has been identified as a replacement for volumetric testing and also prevents the bottles from being taken physically out of the system. It is estimated that the cost savings of using this technique are more than US$300,000.
“There is less downtime, because previously you’d have to take the 90 bottles and x-ray them,” Fanning said. “With this, you pump the bottles to 105-110% pressure and listen for a flaw or crack growth.
“We used the JM3 compressors to pump the bottles to their max pressure capacity to stress them and see if there were any cracks or flaws. Whenever a crack grows, a sensor sounds letting us know there’s something there.”
The process took several hours and the weather conditions had to be just right. “We couldn’t do it in the rain because it’s so sensitive to any noise outside,” Fanning added.
October 26, 2017