Tony Bigsby, pipefitter in the Model and Machine Shop at Arnold Air Force Base, welds a pipe for one of the test cells on base. Bigsby is one of about 40 craft workers in the Model Shop certified to perform welding. The welders support general operations at Arnold, including the repair of existing infrastructure, and testing, including the fabrication of piping for test cells. They also perform various types of welding on a variety of metals. (U.S. Air Force photo by Bradley Hicks) (This image was altered by obscuring badges for security purposes)