Tank and Pressure Vessel Skirt Thermal Ratcheting Prevention Device

Abstract

A Tank and Pressure Vessel Skirt Ratchet Prevention Device for the reduction or elimination of relative deflection of a tank or vessel ( 29 ) skirt ( 25 ) is presented. In vertical tank or vessel ( 29 ) design where the tank shell ( 23 ) and the tank or vessel ( 29 ) bottom ( 22 ) are connected together by a knuckle ( 24 ) it is common to place a skirt ( 25 ) and skirt base plate ( 26 ) under the shell. The skirt ( 25 ) and skirt base plate ( 26 ) support the tank or vessel ( 29 ) structure, product and transmit these and environmental loads and anything on tank shell ( 23 ) into the foundation ( 21 ). Cyclic loads change the diameter of the skirt, ( 25 ) the tank shell ( 23 ) and skirt base plate ( 26 ). The addition of a ratchet prevention member ( 27 ) or an anti-friction device ( 30 ) reduces relative deflection and fatigue at these locations.

I claim:  
     
         1 . A jacket ratchet prevention device with one edge contiguous to a storage tank shell comprising at least one structural element; so that one edge of said jacket is contiguous to the tank shell; such that the motion of the other edge of said jacket is slidably impeded due to friction; such that an axial and a horizontal force are urging said jacket; such that deflection of the jacket is prevented; such that the two jacket edge diameters are prevented from becoming unequal; such that said storage tank shell is the pressure boundary membrane of a containment device; whereby ratcheting of the jacket ends are prevented; whereby urging the jacket base plate end; such that said jacket edge diameters are equal; thereby reducing stresses in said jacket and said storage tank shell. 
     
     
         2 . The device in  claim 1 , wherein said forces are from the weight of the tank structure, a product contained in the tank shell, or from an environmental load. 
     
     
         3 . The device in  claim 1 , wherein an unattached edge of said jacket ratchet prevention device is contiguous to a jacket. 
     
     
         4 . The device in  claim 1 , wherein said jacket is a pressure vessel or tank skirt. 
     
     
         5 . The device in  claim 1 , wherein the shell to the ratchet prevention device connection is disposed near a transition from a cylindrical to a conical section. 
     
     
         6 . The device in  claim 1 , wherein the shell to the ratchet prevention device connection is disposed near a transition from a cylindrical section to a portion of a head. 
     
     
         7 . The device in  claim 1 , wherein said horizontal forces are a result of cyclic thermal expansion. 
     
     
         8 . The device in  claim 1 , wherein an unattached edge of said jacket ratchet prevention device is contiguous to the skirt base plate. 
     
     
         9 . A jacket ratchet prevention device contiguous to a storage tank skirt base plate comprising at least one antifriction device; so that one edge of said jacket is contiguous to the tank shell; such that the motion of the other edge of said jacket is slidably impeded due to friction; such that an axial and a horizontal force are urging said jacket; such that deflection of the jacket is reduced; such that said storage tank shell is the pressure boundary membrane of a containment device; whereby reducing the difference of the two jacket edge diameters; whereby ratcheting of the jacket ends is reduced; whereby reducing the resisting force urging the sliding end of the jacket; such that said jacket edge diameters are closer; thereby reducing stresses in said jacket and said shell. 
     
     
         10 . The device in  claim 9 , wherein said forces are from the weight of the tank structure, a product contained in the tank shell, or from an environmental load. 
     
     
         11 . The device in  claim 9 , wherein said horizontal forces are a result of cyclic thermal expansion. 
     
     
         12 . A tank drift device so as to prevent a tank or vessel from sliding due to lateral urging comprising:
 a. a structure contiguous to the underside of the bottom of the tank; such that said tank drift device is disposed near the center of the tank and   b. a reinforcing structure to effectively transmit urging forces from said structure to the tank and   c. an adequately reinforced, keyed recess in a tank foundation; such that said tank drift device structure fits into the keyed foundation,   whereby, movement of the tank at the perimeter is greatly reduced.   
     
     
         13 . The device of  claim 12 , wherein said tank drift device is a bottom sump. 
     
     
         14 . The device of  claim 12 , wherein said tank drift device is a conical bottom.