W. CONSHOHOCKEN, PA--ASTM International Committee E07 on nondestructive testing has developed a new standard for recertifying gas-filled pressure vessels used aboard aircraft for fire suppression. The new standard, ASTM E2863, Practice for Acoustic Emission Examination of Welded Steel Sphere Vessels Using Thermal Pressurization, is under the jurisdiction of Subcommittee E07.04 on Acoustic Emission Method.

According to James Mitchell, president, Structural Diagnostic Services Inc., and vice chairman of E07.04, the impetus for developing the standard was the search for a less costly and faster means to recertify Halon bottles that are sealed and have no opening. The U.S. Department of Transportation requires periodic recertification of the bottles.

Mitchell says that the acoustic emission method requires the application of stress to induce signals from flaws in the test object.

"In the case of pressure vessels, the stress is generally from an external source, such as a pump," says Mitchell. "The new standard uses an external heat source to increase the gas pressure inside the pressure vessel to achieve the added pressurization. ASTM E2863 is of particular interest for pressure vessels that are sealed and cannot be pressurized in any other way."

ASTM E2863 will allow the large number of Halon bottles found on aircraft and used for fire suppression to be recertified at a maintenance facility and immediately returned to the aircraft.

E07.04 is continuing to work on numerous applications for acoustic emission from metallic and composite structures and welcomes participation, particularly from users of ASTM E2863.