ORIGINAL: furloughed ual
what actually is a pipe collapse (besides the obvious)......what causes it? Does the metal burn through, does it become annealed and too soft to maintain shape, never seen one.......
A collapse usually occurs post a hot start (or starts). The direct flame weakens the metal, this is usually evidenced by strong bluing/purple or worse yet wrinkeling. Going against what you would think the pipe fails due to negative pressure. The front part of the pipe is a negative pressure area due to the venturi effect of the exhaust stream, so the pipe looses integrity and collapses. Scotty