Have you ever done a double-take when looking at an inspection photograph? I certainly did when an engineer at a valve manufacturer sent me an inspection photograph and asked, “See anything wrong with this picture?” “Yeah,” I replied. Someone had installed two expansion relief valves back-to-back on the body bleed of a twin-seated plug valve used for isolation in our gasoline tank farm. The valve casting safety port was cracked because expansion flow was choked. “Dumb, really dumb,” I remarked. How did this get by?
