N.A.T.O. The defensive military alliance formed in 1949 by ten european countries. WARSAW PACT A military alliance formed in 1955 by the Soviet Union Netherlands. Norway.
Tank Rings. Tank rings filled with gravel lift the tank above the surrounding grade. This keeps the tank out of standing water and increases the life of the tank bottom.
By Doug Stelling. The annular plate-to-shell junction is one of the most critical areas in an API 650 Tank, and is one of the most difficult areas in which to assess corrosion. The annular plate typically rests on a crushed stone or concrete ring wall, and joins the highly stressed shell of the tank to the bottom plates. The bottom plates are for the most part supported by the tank pad or foundation, and are lowly stressed.