API 653 Calculation Tests

document.xls

Tank 1 info

Random Tank 1A Crude Oil Storage Tank is inspected.

SN CMP Manufacturer

1982 Year of Manufacture

API 650 Manufacturing Specification

( D ) 150 ft Tank Diameter

12 ft Liquid Fill Height

( G ) 0.80 Specific Gravity of Product

A662-B Shell material

( Y ) ? Minimum Yield Strength

( T ) ? Ultimate Tensile Strength

( S ) ? Max Allowable Stress

( E ) ? Joint Efficiency

Butt Welds Joint Type

Spot Rt Radiography Done

6ft x 3ft

0.590 inch

0.453 inch 2nd course thickness

0.315 inch 3rd course thickness

0.315 inch

Plate dimensions (All courses)

1st course thickness (Bottom)

4th course thickness (Top)

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Tank 1 info

Random Tank 1

Tank Survey History

1-Jan-90

Second course plate measured 0.460".

22-Feb-00


6-Jan-04


13-Jan-09

where paint failed some years ago. 1ft above the circumferential weld. (Locally thinned area)

The depth of the corrosion was measured by placing a straight edge over the corroded

area and measuring the corrosion depth with a vernier at equally spaced increments over the length L.

0.370 inch Depth Measurement (Top)

0.347 inch Depth Measurement




0.327 inch Depth Measurement (Bottom)

a)

? Least Minimum Thickness in the corroded section.

b)shell.

( L ) ? Critical Length of corroded section.

c)

? Average thickness of corroded section.

d)

( S ) ? Maximum allowable stress.

e)recommendation.

? Minimum acceptable thickness for the corroded area.

f)

? Long Term Corrosion Rate.

g)

? Short Term Corrosion Rate.

h)

? Remaining life.

i)

External Corrosion was found on the second course plate (0.453 inch) on the east side of the tank

Corroded area is at 8 ft below the Maximum fill height of the tank.

Determine the Least Minimum Thickness on the corroded part of a tank.

( t2 )

Calculate the Critical Length for thickness measurement on the corroded part of a tank

Calculate the Average Thickness of the corroded section.

( t1 )

Calculate the Maximum Allowable Stress for the corroded section.

Calculate the Minimum Acceptable Thickness for this corroded area and furnish a

( tmin )

Calculate the Long Term Corrosion Rate.

Calculate the Short Term Corrosion Rate.

Calculate the Remaining Life for the Tank.

Calculate the Hydrostatic Test Height.

document.xls

Tank 1 info

? Height from the bottom of corroded area to the Hydostatic test height.

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Tank 2 info

Random Tank 2

No Info Manufacturer


? Manufacturing Specification


( H ) 35 ft Liquid Height


No Info Shell material






Spot Radiography Done

19.7 x 4.92 ft

0.276 inch



0.276 inch 4th course thickness


0.276 inch

A Crude Oil Storage Tank is inspected. (T1202)




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Tank 2 info

Random Tank 2

The following remaining thicknesses in the corroded area were obtained by ultrasonic equipment, and were

taken over the critical length in equal increments.








a)


b)shell.


c)


d)


e)recommendation.


f)


g)


h)

? Remaining life.

i)


Internal Corrosion was found on the first course plate (.276 inch) on the east side of the tank.

2ft above the annular plate which is 33 ft below the liquid level. (Locally thinned area)


( t2 )



( t1 )



( tmin )





document.xls

Tank 3 info

Random Tank 3

Tissot & Cie Manufacturer






? Shell material




( E ) 0.85 Joint Efficiency


? Radiography Done

23.56 x 6.67 ft

0.610 inch





0.250 inch





document.xls

Tank 3 info

Random Tank 3










a)


b)shell.


c)


d)


e)recommendation.


f)


g)


h)

? Remaining life.

i)



Internal Corrosion was found on the third course plate (0.394 inch) on the south side of the tank.

24 ft below the liquid level. (Locally thinned area)


( t2 )



( t1 )



( tmin )





document.xls

Tank 4 info

Random Tank 4

Tissot & Cie Manufacturer






? Shell material







23.56 x 6.67 ft

0.610 inch





0.250 inch





document.xls

Tank 4 info

Random Tank 4









a)


b)shell.


c)


d)


e)recommendation.


f)


g)


h)

? Remaining life.

i)



Internal Corrosion was found on the second course plate (0.512 inch) on the north side of the tank.

Corosion is on the bottom weld of the 2nd course and above.



( t2 )



( t1 )



( tmin )





document.xls

Tank 5 info

Random Tank 5A Crude Oil Storage Tank is inspected. T1501

SN CMP Manufacturer


BS2654 Manufacturing Specification




Shell material







12.0 x 8.0 ft

0.944 inch





0.314 inch




document.xls

Tank 5 info

T1501A Crude Oil Storage Tank is inspected.









a)


b)shell.


c)


d)


e)recommendation.


f)


g)


h)

? Remaining life.

i)


Internal Corrosion was found on the third course plate (0.590 inch) on the north side of the tank.

Corosion is on the bottom weld of the 3rd course and above.



( t2 )



( t1 )



( tmin )





document.xls

Tank 6 info

Random Tank 6A Crude Oil Storage Tank is inspected. T3501

SN CMP Manufacturer


BS2654 Manufacturing Specification




Shell material







12.0 x 8.0 ft

0.944 inch





0.314 inch




document.xls

Tank 6 info

T1501A Crude Oil Storage Tank is inspected. T3501

-------- ft below the liquid level. (Locally thinned area)









a)


b)shell.


c)


d)


e)recommendation.


f)


g)


h)

? Remaining life.

i)


Internal Corrosion was found on the fourth course plate (-------- inch) on the north side of the tank.

Corosion is on the bottom weld of the 3rd course and above.


( t2 )



( t1 )



( tmin )





document.xls

Solution 1

Random Tank 1

a) Determine the Least Minimum Thickness on the corroded part of a tank.

0.315" Least Minimum Thickness in the corroded section.

b) Calculate the Critical Length for thickness measurement on the corroded part of a tankshell.

( L ) 25.43" Critical Length of corroded section.

c) Calculate the average thickness of the corroded section.

0.352" Average thickness of corroded section.

d) Calculate the maximum allowable stress for the corroded section.

( S ) Maximum allowable stress.

e) Calculate the minimum acceptable thickness for this corroded area and furnish arecommendation.

0.1" Minimum acceptable thickness for the corroded area.

f) Calculate the long term Corrosion Rate.

0.0076 inch/year Long Term Corrosion Rate.

g) Calculate the most recent short term Corrosion Rate.

0.0152 inch/year Short Term Corrosion Rate.

h) Calculate the Remaining Life for the Tank.

14 years Remaining life.

( t2 )

( t1 )

27 885 lbf/in2

( tmin )

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Solution 2

Random Tank 2


Least Minimum Thickness in the corroded section.


( L ) Critical Length of corroded section.


Average thickness of corroded section.




Minimum acceptable thickness for the corroded area.


Long Term Corrosion Rate.


Short Term Corrosion Rate.


Remaining life.

( t2 )

( t1 )

( tmin )

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Solution 3

Random Tank 3
















Remaining life.

( t2 )

( t1 )

( tmin )

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Solution 4

Random Tank 4
















Remaining life.

( t2 )

( t1 )

( tmin )

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Solution 5

Random Tank 5
















Remaining life.

( t2 )

( t1 )

( tmin )

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Solution 6

Random Tank 6
















Remaining life.

( t2 )

( t1 )

( tmin )

API 653 Calculation Tests

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