Classification of Tanks

• Atmospheric Tanks (API 650) Pressure varies from atmospheric up to 2.5

psi above atmospheric. • Low Pressure Tanks (API 620) These tanks are designed to operate from

atmospheric up to 15 psig.

Scope

Establishes minimum requirements for material, design, fabrication, erection, and testing for Vertical, Cylindrical, Aboveground, closed- and open-top, welded carbon or stainless steel storage tanks in various sizes and capacities for internal pressures approximating atmospheric pressure

Scope

• Applies only to tanks whose entire bottom is uniformly supported.

• Tanks in non-refrigerated service that have a

maximum design temperature of 93°C (200°F) or less.

Status of Appendices

Design

Tank Capacity

Special Considerations

• Foundation

– The adequacy of the foundation is the responsibility of the Purchaser

• Corrosion Allowance

– Guidance to the Purchaser for considering corrosion allowance

• Service Conditions – The Purchaser specify any special requirements as

required by anticipated service conditions

Tank Bottoms

Tank Bottoms

Bottom Design — Design to, permit complete draw-off, minimize product contact and to utilize max. tank capacity and prevention of corrosion of bottom plate. Two types of tank bottom: • Cone down bottom (Bottom down) • Cone up bottom (Bottom up)

Annular Plate

Annular Plate

• Annular bottom plates shall have a radial width that provides at least 600 mm (24 in.) between the inside of the shell and any lap-welded joint in the remainder of the bottom.

• Annular bottom plate projection outside the shell shall meet the requirements of 5.4.2 (at least 50 mm)

• A greater radial width of annular plate is required when calculated as follows : 215*tb/(H*G)0.5

Materials

Material Group

Selection

Materials

Materials

• ASTM A 36 ≦ 40 mm. • ASTM A 283, Grade C ≦ 25 mm. • ASTM A 285, Grade C ≦ 25 mm. • ASTM A 516 Grades 55, 60, 65, and 70 ≦ 40 mm (insert plates and

flanges to a maximum thickness of 100 mm). • ASTM A 537, Class 1 and Class 2 ≦ 45 mm (insert plates to a maximum

thickness of 100 mm). • ASTM A 573, Grades 58, 65, and 70 ≦ 40 mm.

Shell Design

• Shell Design

– Shell designed on the basis that the tank is filled to level H with a specific gravity (SG) product value furnished by the customer.

– Manufacturer must furnish a drawing that lists: • Required shell t (include CA) for both product and

hydro-test • Nominal thickness used • Material specification • Allowable stresses

Shell Design

Sd and St is selected from the table of permissible materials and allowable stresses is API Std 650

Shell Design

Not allowed for shells with diameters greater than 60m (200 ft).

td = 4.9*D*(H-0.3)*G/Sd + CA tt = 4.9*D*(H-0.3)/St

td = design shell thickness, in mm, tt = hydrostatic test shell thickness, in mm, D = nominal tank diameter, in m, H = design liquid level, in m, G = design specific gravity of the liquid to be stored CA = corrosion allowance, in mm, as specified by the Purchaser (see 5.3.2), Sd = allowable stress for the design condition, in MPa (see 5.6.2.1), St = allowable stress for the hydrostatic test condition, in MPa (see 5.6.2.2)

Shell Design

• Shells with diameters greater than 60 m.

– Variable Design-Point

• See Appendix K

– Elastic Analysis (Finite Element Method Analysis)

L/H ≦ 1000/6, L = (500*D*t)0.5

Materials

• The calculated stress for each shell course shall not be greater than the stress permitted for the particular material used for the course.

• When the allowable stress for an upper shell course is lower than the allowable stress of the next lower shell course, then either a or b shall be satisfied. a. The lower shell course thickness shall be no less than the

thickness required of the upper shell course for product and hydro-static test loads.

b. The thickness of all shell courses shall be that determined from an elastic analysis per 5.6.5 using final plate thicknesses.

Shell Design

Diameter

Minimum Thickness

≤ 15m (50')

5mm (3/16 in)

15m < D ≤ 36m

50' < D < 120'

6mm (1/4 in)

36m < D ≤ 60m

120' < D ≤ 200'

8mm (5/16 in)

> 60m (200')

10mm (3/8 in)

Thermal Stress Relief

5.7.4.2 When the shell material is Group I, II, III, or IIIA, all opening connections NPS 12 or larger in nominal diameter in a shell plate or thickened insert plate more than 25 mm (1 in.) thick shall be prefabricated into the shell plate or thickened insert plate, and the prefabricated assembly shall be thermally stress-relieved within a temperature range of 600°C – 650°C (1100°F – 1200°F) for 1 hour per 25 mm (1 in.) of thickness prior to installation.

5.7.4.3 When the shell material is Group IV, IVA, V, or VI, all opening connections requiring reinforcement in a shell plate or thickened insert plate more than 13 mm (1/2 in.) thick shall be prefabricated into the shell plate or thickened insert plate, and the prefabricated assembly shall be thermally stress relieved within a temperature range of 600°C – 650°C (1100°F – 1200°F) for 1 hour per 25 mm (1 in.) of thickness prior to installation.

Wind Girders

Z = 1/17*D2H2 (V/190)2

der

Intermediate Wind Girders

Where

H1 = vertical distance (ft) between intermediate wind

girder and top angle or top wind gir

t = as ordered thickness (in) of the top shell course

D = nominal tank diameter (ft)

If the Transformed shell height is > H1 then an intermediate wind girder is required.

H1 = 9.47*t*(t/D)3/2*(190/V)2

Wtr = W (tuniform/tactual) (5/2)

Shell Openings

Roof Design

• Roofs

– Fixed roofs

• Roofs and structure designed support load combinations in Appendix R.

• Roof Plates minimum of 5mm

Fixed Roof Design

Cone Roof

Fixed Roof Design

Cone Roof Design

Cone Roof Design

Cone Roof Design

Truss Supported Cone Roof

Dome Roof

Umbrella Roof

Appendix R

Top Angle

Top Angle

Frangible Roof

a. For tanks 15 m (50 ft) in diameter or greater, the tank shall meet all of the following: 1. The slope of the roof at the top angle attachment does not exceed 2:12. 2. The roof support members shall not be attached to the roof plate. 3. The roof is attached to the top angle with a single continuous fillet weld on the

top side (only) that does not exceed 5 mm(3/16 in.). No underside welding of roof to top angle (including seal welding) is permitted.

4. The roof-to-top angle compression ring is limited to details a - e in Figure F-2. 5. All members in the region of the roof-to-shell joint, including insulation rings, are

considered as contributing to the roof-to-shell joint cross-sectional area (A) and this area is less than the limit shown below:

A = DLs/(2* π *Fy*tan(θ))

Frangible Roof

b. For self-anchored tanks with a diameter greater than or equal to 9 m (30 ft) but less than 15 m (50 ft), the tank shall meet all of the following: 1. The tank height is 9 m (30 ft) or greater. 2. The tank shall meet the requirements of 5.10.2.6.a.2-5 3. The slope of the roof at the top angle attachment does not exceed 3/4:12. 4. Attachments (including nozzles and manholes) to the tank shall be designed to

accommodate at least 100 mm (4 in.) of vertical shell movement without rupture. 5. The bottom is butt-welded.

Wind Load

Hydro-static Testing

7.3.5 Testing of the Shell If water is available for testing the shell, the tank shall be filled with water as

follows: (1) to the maximum design liquid level, H; (2) for a tank with a tight roof, to 50 mm (2 in.) above the weld connecting the

roof plate or compression bar to the top angle or shell; (3) to a level lower than that specified in Subitem 1 or 2 when restricted by

overflows, an internal floating roof, or other freeboard by agreement between the Purchaser and the Manufacturer,

(4) to a level of seawater producing a bottom of shell hoop stress equal to that produced by a full-height fresh water test.

F.4.4 When the entire tank is completed, it shall be filled with water to the top angle or the design liquid level, and the design internal air pressure shall be applied to the enclosed space above the water level.

F.7.6 After the tank is filled with water, the shell and the anchorage shall be visually inspected for tightness. Air pressure of 1.25 times the design pressure shall be applied to the tank filled with water to the design liquid height

Anchor Bolt Uplifting

Marking

Appendix A

• Optional Design Basis for Small Tanks

–

–

–

–

–

Maximum shell thickness of 13mm (1/2”)

Only applicable to lower strength materials

Design equations are simplified

Inspection requirements can be reduced

Provides a table of typical sizes,

capacities, and shell plate thicknesses

Appendix J

Shop Assembled Storage Tanks

a. For tanks with a diameter less than or equal to 3.2 m (10.5 ft) – 4.8 mm (3/16 in.).

b. For tanks with a diameter greater than 3.2 m (10.5 ft) – 6 mm (0.236 in.).

317L.

Appendix S

• Stainless Steel Tanks • This appendix covers materials, design,

fabrication, erection, and testing requirements for austenitic stainless steel storage tanks constructed of material grades 304, 304L, 316, 316L, 317, and 317L

Appendix AL

• Aluminum Tanks

– Imported from ASME B96.1 Welded Aluminum Alloy Storage Tanks

– ASME B96.1 has been withdrawn

Appendix C

External Floating Roofs

Appendix C

• Type of EFR - Single Deck Pontoon Type - Double Deck Pontoon Type

C.3.4 PONTOON DESIGN C.3.4.1 Floating roofs shall have sufficient buoyancy to remain afloat on liquid with a specific gravity of the lower of the product specific gravity or 0.7 and with primary drains inoperative for the following conditions:

a. 250 mm (10 in.) of rainfall in a 24-hour period over the full horizontal tank area rainfall.

b. Single-deck and any two adjacent pontoon compartments punctured and flooded in single-deck pontoon roofs and any two adjacent compartments punctured and flooded in double-deck roofs, both roof types with no water or live load.

Appendix C

External Floating Roofs

Appendix C

External Floating Roofs

Appendix C

External Floating Roofs

Appendix C

The floating roof has mechanical seal attached to its full perimeter . The rim seal covers the space between the floating roof and the tank shell (side wall)

Appendix H

Internal Floating Roofs

Appendix H

a. All internal floating roof design calculations shall be based on

the lower of the product specific gravity or 0.7.

b. All internal floating roofs shall include buoyancy required to

support at least twice its dead weight.

c. All internal floating roofs with multiple flotation compartments

shall be capable of floating without additional damage after any

two compartments are punctured and flooded.

d. To safely support at least two men walking anywhere on the

roof while it is floating without damaging the floating roof. One

applied load of 2.2 kN (500 lbf) over 0.1 m2 (1 ft2) applied

anywhere on the roof addresses two men walking.

Appendix H

Appendix H

Appendix H

Internal Floating Roofs

Appendix H

Appendix H

Appendix H

roofs

Appendix H

Cable suspended

floating

Appendix G

Aluminum Domes

Appendix G

Aluminum Domes

• With integral tension ring

– Dome resists all forces

– Supports slide radial direction

Without tension ring

– Tank resists all forces

– Dome is fixed to the tank

•

Seismic Design

Sloshing

•Any motion of the free liquid surface inside its containers.

•Depending on the type of disturbance and container shape, the free liquid surface can experience different types of motion; simple planar, non-planar, rotational, irregular beating, symmetric, asymmetric.

Sloshing

Damage to the Oil Storage Tanks due to Liquid Sloshing in the Past Earthquakes

• 1964 Niigata Earthquake • Nihonkai-chubu Earthqukae (1983) • 2003 Tokachi-oki Earthquake

Sloshing

Sloshing

Liquid sloshing in cylindrical tank

Sloshing

• Resonance between liquid (oil) and ground motion • Larger diameter – longer sloshing period • Higher liquid height – shorter sloshing period

D=100 m T=13 s

D=50 m T=8 s

D=10 m T=3 s

Appendix E

Appendix E – Hoop Stress

Appendix E - Overturning

Appendix E - Freeboard

Appendix M

Requirements for Tanks Operating at Elevated Temperatures 260°C (500°F)

Appendix V

• Design for external pressure

– Applicable to

pressures up to 6.9 KPa (1.0 PSI)

Appendix F

• Design for Internal Pressures

– Covers from Atmospheric up

to 18 KPa (2.5 PSI)

Appendix F