STEEL STAND-PIPES AND ELEVATED TANKS ON TOWERS. CHAP. XI. 



Details of Construction. 14. The plates forming the sides of cylindrical tanks shall be of 

 different diameters, so that the courses shall lap over each other, inside and outside, alternately. 



15. The joints for the horizontal seams, and for the radial seams in spherical bottoms, shall 

 preferably be lap joints. 



16. For vertical seams double-riveted lap joints shall be used for |, &, and f in. plates. Triple 

 lap joints shall be used for ^ and f in. plates; double-riveted butt joints shall be used for $, f, 

 H and f in. plates; and triple-riveted butt joints for jf, I. if and I in. plates. 



17. Rivets f in. in diameter shall be used for | in. plates; rivets f in. in diameter shall be 

 used for ^s m - plates; rivets I in. in diameter shall be used for f to f in. plates, inclusive. Rivets 

 I in. in diameter shall be used for j| in. and I in. plates. 



Rivets shall be spaced so as to make the most economical seams (70 to 75 per cent efficiency). 

 A table of riveted joints is given in Table Ila. 



1 8. In no case shall the spacing between rivets along the caulked edges of plates be more 

 than ten times the thickness of the plates. All rivets shall be entered from the inside of the 

 tank, and shall be driven from the outside, that is, new heads on rivets shall always be formed from 

 the opposite side of the plate on which the caulking is done. 



19. Plates f in. thick, and not more than f in. thick, shall be sub-punched with a punch ^ in. 

 smaller in diameter than the nominal size of the rivets, and shall be reamed to a finished diameter 

 not more than YS m - larger than the rivet. Plates thicker than | in. shall be drilled. 



20. The minimum thickness of the plates for the cylindrical part shall be f in. The thick- 

 ness of the plates in spherical bottoms shall never be less than that of the lower course in the 

 cylindrical part of the tank. 



21. The facilities at the plant where the material is to be fabricated will be investigated 

 before the material is ordered. 



22. All plates shall be sheared or planed to a proper bevel along the edges for caulking. 



23. All plates shall be caulked along the beveled edges from the inside of the tank, and with a 

 round-nosed tool. The use of foreign material for caulking, such as lead, copper, filings, cement, 

 etc., will not be permitted. 



24. The plates in tanks for the storage of oil shall be beveled on both sides for outside and 

 inside caulking. 



25. The radial sections of spherical bottoms shall be made in multiples of the number of 

 columns supporting the tank, and shall be reinforced at the lower parts, where holes are made 

 for piping. 



26. When the center of the spherical bottom is above the point of connection with the cylin- 

 drical part of the tank, there shall be provided a girder at said point of connection to take the hori- 

 zontal thrust. The horizontal girder may be made in connection with a balcony. This also 

 applies where the tank is supported by inclined columns. 



27. The balcony around the tank shall be 3 ft. wide, and shall have a floor-plate J in. thick, 

 which shall be punched for drainage. The balcony shall be provided with a suitable railing, 

 3 ft. 6 in. high. 



28. The upper parts of spherical bottom plates shall always be connected on the inside of the 

 cylindrical section of the tank. 



29. In order to avoid eccentric loading on the tower columns, and local stresses in spherical 

 bottoms, the connections between the columns and the sides of the tank shall be made in such a 

 manner that the center of gravity of the column section intersects the center of connection between 

 the spherical bottom and the sides of the tank. Enough rivets shall be provided above this inter- 

 section to transmit the total column load. 



30. If the tank is supported on columns riveted directly to the sides, additional material shall 

 be provided in -the tank plates riveted directly to the columns to take the shear. The shear may 

 be taken by providing thicker tank plates, or by reinforcement plates at the column connections, 

 while bending moments shall be taken by upper and lower flange angles. Connections to columns 

 shall be made in such a manner that the efficiency of the tank plates shall not be less than that 

 of the vertical seams. 



31. For high towers, the columns shall have a batter of I to 12. The height of the tower 

 shall be the distance from the top of the masonry to the connection of the spherical bottom, or 

 the flat bottom, with the cylindrical part of the tank. 



32. Near the top of the tank there shall be provided one Z-bar to act as a support for the 

 painter's trolley, and for stiffening the tank. Its section modulus shall not be less than Z? 2 / 2 5O, 

 where D is the diameter of the tank in feet. If the upper part of the tank is thoroughly held by 

 the roof construction, this may be reduced. 



33. On large tanks, circular stiffening angles shall be provided in order to prevent the plates 

 from buckling during wind storms. The distance between the angles shall be determined by the 

 formula: 



d = 900 t*/D, 



