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    Shell Minimum Thickness Calculations: D (FT) G E Fill Height (FT)

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    trijaya landscape
    The document contains calculations to determine the minimum required thickness (tmin) of tank shell courses based on parameters like height, diameter, material properties, and stress allowances. It also contains calculations to determine the remaining corrosion allowance (Ca) and corrosion rate (Cr) based on current (tact) and previous (tprev) thickness measurements in order to estimate the remaining life (RL) of each shell course. Sample calculations are provided for a tank with a 25 foot diameter using A36 and A285M C steel for the first and second courses respectively.

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    Shell Minimum Thickness Calculations: D (FT) G E Fill Height (FT)

    Uploaded by

    trijaya landscape
    95 views2 pages
    The document contains calculations to determine the minimum required thickness (tmin) of tank shell courses based on parameters like height, diameter, material properties, and stress allowances. It also contains calculations to determine the remaining corrosion allowance (Ca) and corrosion rate (Cr) based on current (tact) and previous (tprev) thickness measurements in order to estimate the remaining life (RL) of each shell course. Sample calculations are provided for a tank with a 25 foot diameter using A36 and A285M C steel for the first and second courses respectively.

    Original Description:

    shell calculations

    Original Title

    Shell Calculations

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    The document contains calculations to determine the minimum required thickness (tmin) of tank shell courses based on parameters like height, diameter, material properties, and stress allowances. It also contains calculations to determine the remaining corrosion allowance (Ca) and corrosion rate (Cr) based on current (tact) and previous (tprev) thickness measurements in order to estimate the remaining life (RL) of each shell course. Sample calculations are provided for a tank with a 25 foot diameter using A36 and A285M C steel for the first and second courses respectively.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    95 views2 pages

    Shell Minimum Thickness Calculations: D (FT) G E Fill Height (FT)

    Uploaded by

    trijaya landscape
    The document contains calculations to determine the minimum required thickness (tmin) of tank shell courses based on parameters like height, diameter, material properties, and stress allowances. It also contains calculations to determine the remaining corrosion allowance (Ca) and corrosion rate (Cr) based on current (tact) and previous (tprev) thickness measurements in order to estimate the remaining life (RL) of each shell course. Sample calculations are provided for a tank with a 25 foot diameter using A36 and A285M C steel for the first and second courses respectively.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
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    Tank Shell Minimum Thickness and Remaining Life Calculations Date

    File No. Report No. Client Tank No. Temp. (degF) Initials
    300200 test 50

    SHELL MINIMUM THICKNESS CALCULATIONS

    tmin = 2.6(H-1)DG
    SE
    Where:

    H = The height above the bottom of the course of study to the maximum liquid level height
    of the product, in ft. For corroded or pitted areas, H = the height from the bottom of the
    corroded or pitted area to the maximum liquid level height of the product, in ft.

    tmin = The calculated minimum acceptable shell thickness, in inch (cannot be less than
    0.10 inch for any course). The minimum acceptable shell thickness allowed by API-653 and
    STI-SP001 for tank size, in inch .

    D = Nominal diameter of tank, in ft.

    G = Highest specific gravity of the contents (including test water if tank will, or may, be
    tested in the future).

    S = Maximum allowable stress, in psi. For welded tanks; use the smaller of 0.80Y of 0.429T
    for bottom and second course or the smaller of 0.88Y or 0.472T for all other courses. For
    riveted tanks; S = 21000 psi. For STI Tank Inspections S = 26000 psi (E = 1)

    Y = Specified minimum yield strength of the plate, in psi; use 30000 psi if not known (N/A
    for riveted tanks).

    T = The smaller of the specified minimum tensile strength of the plate or 80000 psi; use
    55000 psi if not known (N/A for riveted tanks).

    E = Original joint efficiency for the tank. For welded tanks; use API-653, Table 2-1 ; use E =
    1.0 when evaluating the retirement thickness in a corroded plate, when away from welds or
    joints by at least the greater of one inch or twice the plate thickness. For riveted tanks; use
    E = 1.0 for shell plates greater than 1 inch away from rivets; use the value of E from API-
    653 Table 2-1 when within 1 inch of rivets. For STI Tank Inspections E = 1 where S = 26000
    psi.

    D (ft) 25 G 1.03 E 1.00 Fill Height (ft) 200.0

    Material Crs H (ft) H (ft) S (psi) tmin (inch)


    Course 1 A 36 200.0 24900 0.535
    Course 2 A 285M C 23600 0.100
    Tank Shell Minimum Thickness and Remaining Life Calculations Date
    File No. Report No. Client Tank No. Temp. (degF) Initials
    300200 test 50

    SHELL REMAINING LIFE CALCULATIONS

    Ca = tact-tmin = Remaining Corrosion Allowance (inch)


    Cr = tprev-tact / Y = Corrosion Rate (inch/Yr)
    RL = Ca / Cr = Remaining Life (year)
    Y= 20 = Tank age (year)
    Where:

    Ca = Remaining corrosion allowance of the shell course under consideration, in inch.

    Cr = Corrosion rate of the shell course under consideration, in inch per year.

    FHc = Calculated fill Height = (SEtact/2.6DG+1) + (product height below course of interest),
    in ft.

    tact = Minimum thickness measurement of the shell course under consideration, as


    recorded at the time of inspection, in inch.

    tmin = minimum required thickness of shell course, at the maximum allowable fill height,
    in inch.

    tprev = previous thickness measurement of shell course under consideration, as recorded


    at last inspection or nominal thickness if no previous thickness measurements, in inch.

    RL = Estimated remaining life of the shell course under consideration, in year.

    Y = Time span between thickness readings or age of the tank if nominal thickness is used
    for tprev, in year.

    tprev tact tmin Ca Cr RL FHc


    Course 1 0.535
    Course 2 0.100

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