IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 14, Issue 1 Ver. VII (Jan. - Feb. 2017), PP 43-49 www.iosrjournals.org DOI: 10.9790/1684-1401074349 www.iosrjournals.org 43 | Page Geotechnical Aspects of Storage Tank Foundation Types Amin Moradi 1 *, Amir Mahmoudzadeh 2 , Yahya Rahim Safavi 3 1 Master of Technology in Civil Engineering Ph.D Scholar In Reserch Institute Of Shakhes Pajouh Esfahan, Iran 2 Master of Technology in Civil Engineering Head of Department & Chancellor In Reserch Institute Of Shakhes Pajouh Esfahan ,Iran 3 Professor of Political geography Abstract: Storage tanks are available in many shapes: vertical and horizontal cylindrical; open top and closed top; flat bottom, cone bottom, slope bottom and dish bottom. Large tanks tend to be vertical cylindrical, or to have rounded corners transition from vertical side wall to bottom profile, to easier withstand hydraulic hydrostatically induced pressure of contained liquid. Most container tanks for handling liquids during transportation are designed to handle varying degrees of pressure. Keywords: pressure; tanks; shapes; flat bottom; cone bottom; hydraulic hydrostatically I. Introduction How Tanks Are Welded: Four basic welding processes are used in fabricating steel tanks and pressure vessels. Each of the four processes (whether manual or automated) will repeatedly produce quality weldments. But they each have strengths and weaknesses. Prospective tank buyers should be aware of the different processes. In general, the best fabricators focus intensely on assuring outstanding fit-up. Many combine that dedication with the use of automatic weld processes which typically leads to high-quality welds. II. Leak Testing Once a tank is completely welded, the tank will be visually inspected and checked for leaks. Most cylindrical atmospheric tanks are tested at 5 psi. Tank openings are sealed, and compressed air is applied to the tank until the necessary test pressure is achieved. It is important to consider the volume of air applied to the tank when pressurizing. While the test pressure is not that great, the volume of air is significant and, in the event of an accident, can cause severe injury to nearby personnel. Fabricators are required to have a safety relief device on the tank to prevent overpressurization. Once the test pressure is achieved, a soap solution is applied over the welds to identify leaks. Bubbles are created when air leaks through the weld and are readily identified by the tester. Leaks are then repaired before the welds are retested to ensure the tank’s integrity.Testing of tanks should be performed in a well -lit area. All gages, relief valves, and testing equipment should be in good working condition. Soap testing solution should be protected from contaminants. The tank welds should be free of slag, spatter, or foreign materials that prohibit testing.Most double-wall tanks will, in addition to the bubble test, have a vacuum applied to the interstitial space. Comparing a vacuum to the bubble test is like comparing apples to oranges. The vacuum is much more sensitive to leaks than the bubble test, and is most effective at proving simultaneously that both the primary and secondary tanks are tight. III. Surface Preparation Tanks that have coatings or laminates applied directly to the exterior steel shell should be prepared by abrasive blasting, which will remove mill scale and roughen the surface to improve adhesion of the paint or coating. Typically the resultant profile left on the steel is between 1.5 and 3.5 mils deep. The blast medium used is often coal slag, silica sand, or recycled grit. The profile depth depends upon the size, type, and hardness of the blast media; particle velocity; angle of impact; surface hardness; and maintenance of the working mixture. The coal slag and grit tend to give a deeper profile versus the sand. However, the sand tends to remove mill scale easier from the surface. Under most circumstances shot or wet blast should not be used for surface preparation on steel tanks. Prior to coating, the tank should be free of abrasives, oil, grease, or other contaminants. Most fabricators will apply the coating to the tank as soon as possible after blast. The longer a blasted, uncoated tank is exposed to the environment, the greater the chance that rust-back will occur, especially in locations subject to high relative humidity. Should rust-back occur, the entire tank should be reblasted. IV. Coatings There are hundreds of different coatings on the market today designed to meet very specific applications. Years ago, many tank suppliers used a coal-tar coating. The coal tar was an excellent coating, and was relatively