Ultrasonic Testing as an Alternative to Radiography
By Rebecca Gurk on Tuesday, June 8th, 2010
The Navy Joining Center (NJC) operated by Edison Welding Institute is working on three U.S. Navy ManTech development projects that address inspection and cladding for surface combatants and advanced weld development for the Expeditionary Fighting Vehicle (EFV). One of the projects involves uses ultrasonic testing as an alternative to radiography.
Radiographic testing (RT) has been used for weld inspection for many years and has proven very successful at detecting volumetric flaws such as porosity and slag. However, planar flaws such as cracks and lack of fusion that are not in direct alignment with the radiation beam can be missed when using RT. Additionally, RT cannot readily determine flaw depth, making precise flaw excavation difficult when repairs are required. These factors, combined with radiation safety concerns and environmental issues associated with the disposal of film processing chemicals have caused industry to look for alternative inspection methods. Consequently, ultrasonic testing (UT) has been steadily replacing RT as the primary nondestructive inspection method for many critical applications.
The objective of the project is to develop and implement ultrasonic inspection procedures and acceptance criteria as an alternative to radiographic inspection as required by the current specification for Naval piping, pressure vessel, and machinery welds. This project is focused on selected materials and weld geometries to encompass the largest percentage of welds. Implementation is scheduled for 2011.