EVERYTHING HAS A NAME
'(<a href="http://www.j-archive.com/media/2005-02-15_DJ_06.jpg" target="_blank">Jimmy of the Clue Crew reports.</a>)  Possibly related to the word "flank", it's a rim or collar, like <a href="http://www.j-archive.com/media/2005-02-15_DJ_06a.jpg" target="_blank">this</a> one on a pipe'
a flange