Naked Science Forum
General Discussion & Feedback => Radio Show & Podcast Feedback => Topic started by: Eric A. Taylor on 13/04/2011 09:09:16
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Loved the kitchen science this week! The question was asked "Can this be done with other things?" Well as a welder I can tell you it's done all the time.
There is a welding job that might seem completely crazy to anyone not familiar with how this works. Oil refineries have a lot of pipes that transport highly flammable things under very high pressers. These pipes tend to wear from the inside out so you could have a pipe that looks fine but has become extremely thin. It can be very very expensive to take the pipe out of service to replace it so a temporary fix has been developed. You take a section of pipe that has an inside diameter equal to the outside diameter of the pipe to be treated. You cut the pipe in half then place the two halves over the old pipe and weld it up. But here's the thing. This treatment must be welded "to code" (very important rules that say how the pipe must be welded and inspected to insure it doesn't fail) as if it were a new pipe. The seam of the new pipe (the two halves) must be welded to the old pipe, which may already be very thin.
If the product in the pipe is stationary this would be a problem. As you heat the metal it gets weaker (like in the Twin Towers) which would cause a failure (almost always fatal to the welder, and IF survived he or she will wish they hadn't). But if the product is flowing then that product will carry away excess heat so the pipe will not fail.
I have won camping bets by saying I could boil water in a paper cup in the camp fire. You take a paper cup and carefully place it DIRECTLY into the flames. The paper in the cup will burn to the water level, then the cup will very slowly burn down as the water boils away. This will NOT work with a polystyrene cup as the polystyrene insulates very well. Also once the water is boiling do not attempt to remove the cup. It will be filled to the very top with boiling water. If your fire burns long enough the water will boil away and burn the cup. If you extinguish the fire before the water is gone just knock the cup over.