118-foot pressure vessel stress relief

Brief illustration. Cooper Heat builds a 118-foot box furnace on rails around an oil-refinery pressure vessel for site stress relief. Used to make the point that there is no vessel so large it can't be put in a furnace, only vessels too expensive to do so.

So stress relieving is not too bad on something the size of this table. But what about a pressure vessel the size of this room? It's a bit of a problem unless you have the furnace. Some of the pressure vessel shops do — there are heat treatment furnaces at a pressure vessel shop that could be 20 foot square by 30 feet long. If you go to Cooper Heat — Cooper Heat has been purchased by something else, but for many years they were a big company around the world doing this — they had a picture of a 118-foot long pressure vessel that would be stood up as part of an oil refinery. Probably 3 or 4 inch thick steel, probably going to have 100 atmospheres of gas in it, 1100 degrees or so. It's thick-walled, all welded construction, and you're going to have all kinds of residual stresses. If you don't do something about the residual stresses, you have problems. You can have fatigue problems because the fatigue's already got a head start — you might apply some other stress in service, but you've already kind of given it a head start with tensile residual stresses in some locations.