As an engineer, sometimes you have a feeling about how your steam plant is running just by the sound. One night as we were steaming west, I toured my steam plant and was hearing a high pitched sound I had never heard before. I looked and looked, but did not find aything unsual. But, we snipes just know sometimes that this is not the normal operating sound. I turned the watch over to my Senior Chief at midnight, describing what I had heard and he said they would continue to investigate and I went to hit the sack.
I showered and crawled in my skid at about 1 am. I slept hard for an hour or so and I can't explain why I woke up. I just did. As I woke up, I had a strange feeling, like I was helpless. Like I had to do something, but I didn't know what. Then I remembered, I had heard an unusual noise in my plant, so I threw on my coveralls and headed back down to the plant. As I got to the bottom of the ladder, No. 1 ship's service turbine generator (supplies 2500 KW electrical power to the ship) tripped offline. I hauled down to the lower level where the TG was and there was steam shooting from the inlet side of the throttle valve. The lower levelman could not get to the isolation valve from where he was standing because of the steam leak. The Senior Chief was screaming over the plant communication curcuit "lowerlevelman, what's going on down there" I was standing where I could isolate the leak and I shut the isolation valve, and the leak slowly stopped. The lowerlevelman explained to Senior Chief what happened and we were able to keep the plant online only because I was able to secure the generator isolation valve in time. The entire engine room would have filled with steam in a matter of minutes and it would have been a major casualty if I had not been able to secure the valve.
I can never explain why I went back down there. I guess I was still bothered and consumed by the strange noise I had heard. It turned out that steam began leaking slowly between the gasket and seating surface of the flange on the inlet to the throttle valve and it was cutting the seating surface. That's what caused the whistle I heard. Once it started, it progessively got worse until it blew. We should have found it. It should never have gotten to the point it did. But, I guess it happens for a reason.
I'm retired now and I will never forget that night.