-It's called initiating explosive device, and its principle is that it expands with heat and contracts with cold. For example, a floor section is heated to a certain extent on the ribs with a baking gun, and then cooled, so that the board surface can be tightened and leveled to achieve the effect of correction and leveling. The initiating explosive device is very difficult, and people who have never done it generally find it very simple. The highest level of initiating explosive device is to deal with the nose and driving building. The ship's nose has the largest linear shape and the thickest plate, which is generally needed.