API SPEC 12D:2008 pdf download

API SPEC 12D:2008 pdf download.Specification for Field Welded Tanks for Storage of Production Liquids.
single-welded lap joint
A joint between two overlapping members, in which the overlapped edge of one member is welded with a fillet weld. tack weld
A weld made to hold parts of a weldment in proper alignment until the final welds are made.
4 Material
4.1 General
Materials listed in this section have been selected to provide adequate strength and reasonable service life. Other matenals having mechanical properties equal to or greater than those listed may be used by agreement between the purchaser and the manufacturer Where higher strength materials are used, the minimum thickness called for in this specification shall not be reduced.
4.2 Plates
Plates shall conform to the latest ektion of one of the folkwing ASTM standards: ASTM A36, ASTM A283 (Grade C or D) and ASTM A285 (Grade C).
Shell plates for which minimum thicknesses have been fixed for practical reasons (greater than required by computation) and which will not under run the required computed thickness by more than 0.01 in.. as well as aN roof and bottom plates, may be purchased on a weight basis, The plate thicknesses or weights, as stipulated herein, are minimums: thicker or heavier material may be required on the order at the option of the purchaser.
4.3 Sheets
Sheets shall conform to the latest revision of ASrM A 1011, Grade C or D. open-hearth process and basic oxygen process. Sheets may be ordered on a weight or thickness basis, at the option of the tank manufacturer
4.4 Welding Electrodes
Manual arc-welding electrodes shall conform to the E60 and E70 Series of Classification (suitable for the electric current ctiaractenstics, the position of welding, and other conditions of intended use) in the latest edition of AWS AS. 1.
4.5 Structural Shapes
Structural shapes shall be of open-hearth, electric-fumace. or basic oxygen process and shall conform to the latest edition of ASTM A36.
4.6 PipIng
Pipe shall conform to Grade A or B of the latest edition of API 5L, ASTM A53, orASTM A106.
4.7 Flanges
Hub slip-on weldmg and welding-neck flanges shall conform to the material requwements for forged carbon steel flanges as specified in ASME 816.5.
4.8 Couplings
Couplings for threaded connections may be supplied with or without recess, complying with the dimensional physical and chemical requirements of the latest edition of API 5L, Grade B. Alternatively, couplings may comply with the latest edition of ASME B16i1.
4.9 Bolting
Tank bolting 1/2 m. in diameter to and iriduding 1 1/2 ii, in length shall conform to the requirements given in Annex A. All other bolting shall conform to the latest revision of ASTM A307. Grade A or B. Unless otherwise specified on the purchase order, black-finish bolts and nuts shall be furnished. When specified to be galvanized, bolts and nuts shall be zinc-coated Ii accordanco with Annex A or the applicable ASTM specification. Alternative materials and/or fwiish conforming to recognized standards for bolting may be furnished by agreement between the purchaser and the manufacturer.
5 Design
5.1 General
Tanks covered by this specification have been designed using established engineering calculations to determine minimum metal thickness and bolting specifications for each size tank filled with water (62.37 lb/ft3 at 60’F) and at the internal pressure specified ii Table 1, Column 2. In order to assure structural stability and Integrity, additional metal thickness has been added to that determined by calculation. The minimum metal thickness specified in this specification shall in no case be decreased.
5.2 Joint Design Definitions
Definitions in Section 3 shall apply to tank-joint designs.
5.3 SIze of Weld
The size of a weld shall be based on the following dimensions:
a) groove weld: the joint penetration (depth of chamfering plus the root penetration when specified);
b) fillet weld: for equal leg fillet welds, the leg length of the largest isosceles right-iriangle which can be Inscribed within the fillet-weld cross-section; while for unequal leg fillet welds, the leg lengths of the largest right-triangle which can be inscribed within the fillet-weld cross-section.