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Atmospheric Storage Tanks design and characteristics

asked Jul 29, 2014 in Mechanical by lampanda (2,450 points)
Can anyone share the "Above Ground" Atmospheric Storage Tanks design and characteristics?

2 Answers

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answered Jul 29, 2014 by ekwuemesam (3,660 points)

The design, fabrication, erection, inspection and testing of above ground atmospheric storage tanks fabricated of carbon steel and austenitic stainless steel should be in accordance with API STD 650.

Tanks within the scope of API STD 650 Appendix A or Appendix J may be entirely designed, fabricated, erected, and inspected per API STD 650 except:

  • All horizontal shell joints shall be complete penetration and complete fusion welds
  • Pneumatic testing per API STD 650 Appendix J should be submitted to the requisition engineer for approval prior to execution
  • The gap between the bottom shell ring and the lap bottom plates at the radial weld location should be a maximum of 1/8"

For tanks with shell thickness greater than 1/2" and temperature less than 32°F, the lowest two shell courses and annular plates should be constructed from fully killed carbon steels manufactured to fine grain practice and normalized or quenched and tempered.

The minimum corrosion allowance of 1/16" should be provided on carbon steel shells and bottom.

Carbon steel bolts for flanged connections should conform to ASTM A 193A 193M, Grade B as a minimum.  Bolts shall consist of regular unfinished machine bolts with one heavy semi-finished hex nut.  ASTM A 307, Grade B may be used for structure purposes only.

For heated tanks (160°F or higher), a bottom rainshield should be installed.

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answered Jul 30, 2014 by alsieg (2,780 points)

Other additional considerations when design storage tank include:

  • The minimum shell thickness for tanks larger than 250' in diameter should not be less than 7/16".
  • Attachments should be designed so that the primary bending stress plus the primary membrane stress is not greater than 1.5 times the shell allowable stress.
  • The wind girders for open top and floating roof tanks should be per API STD 650 except that wind girders specified to be used as walkways should be a minimum of 30" wide and should be located 3'6" below the top of the tank. Wind girders should be seal welded to the shell on their underside.