Joe beat me to it. Today, and for as long as I can remember, tanks permanently mounted in a hull, have had a label that has a number of items listed, including a pressure rating. Since the tanks are often quite large, the pressure ratings are very low. We have a special device made up, that attaches to the vent fitting of a tank, and can use regulated shop air, to test the tanks. Generally, it is no more than 4 PSI, and even at that, the noises the tanks make under that pressure is scary.
I have horrible memories of trying to get at and remove some of these tanks for sure.
