Hesse and rushton method
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HESSE AND RUSHTON METHOD. Pressure Vessels. SHELL THICKNESS. where t p = shell thickness (inch) P = Max allowable working pressure (psi) D = Inside diameter (inch) S = Max allowable tensile stress (psi) (Table 6-6) e = Efficiency of welded joint (Table 6-7)

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Pressure Vessels

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Hesse and rushton method

HESSE AND RUSHTON METHOD

Pressure Vessels


Shell thickness

SHELL THICKNESS

where

tp= shell thickness (inch)

P= Max allowable working pressure (psi)

D= Inside diameter (inch)

S= Max allowable tensile stress (psi) (Table 6-6)

e= Efficiency of welded joint (Table 6-7)

C= Corrosion allowance


Shell thickness1

SHELL THICKNESS

Applicable if:

1. tp< 0.10D

2. tp> tmin


Allowable stress estimation

Allowable Stress Estimation

S = Su x Fm x Fs x Fr x Fa

Where

Su= Minimum Specified Tensile Strength

Fm= Material Factor

Fm= 1 for Grade A material

Fm= 0.97 for Grade B material

Fm= 0.92 for Grade C material

Fs= Temperature Factor (Use Table 6-7)

Fr= Stress Relief (SR) Factor

Fr = 1.06 When SR is applied

Fa= Radiographing Factor

Fa= 1.12 when Radiographing is applied and subsequent repair of defects


Minimum specified tensile strength

Minimum Specified Tensile Strength


Temperature factor

Temperature Factor


Weld joint efficiency

Weld/Joint Efficiency


Stress relief factor

Stress Relief Factor

Stress relieving is mandatory for:

1. tp > 1¼”

2. (For thinner plates)

where D has a minimum value of 20 inches

3. ASTM A – 150

4. ASTM A – 149 (under certain conditions)


Radiographing factor

Radiographing Factor

Radiographingis mandatory for:

1. ASTM A – 150

2. ASTM A – 149 (under certain conditions)

3. Lethal gases application

4. Nuclear Reactor applications


Sample problem 1

Sample Problem 1

A 12 in diameter S-2 Grade A steel has a working pressure and temperature of 500 psi and 300F respectively. Determine the type of weld to be used and plate thickness using Hesse and Rushton method. Assume zero corrosion allowance.


Sample problem 2

Sample Problem 2

Grade A S2 steel, butt welded pressured vessel for lethal gas application has an inside diameter of 20 inches. If the working pressure is 900 psi and the working temperature is 250ºF, what is the shell thickness of the vessel? (Use minimum corrosion allowance and Hesse and Rushton method).


Head configurations

HEAD Configurations

  • Torispherical

    • most common type of head used and usually the most economical to form

    • The I.C.R = I.D of the head or less

      • between 90% to 95% of the I.D of the head

    • The I.K.R = 6% and 10% of the I.C.R of the head

    • The S.F = 10mm and 30mm


Head configurations1

HEAD Configurations

  • 2:1 Semi-Ellipsoidal

    • deeper and stronger than a torispherical head

    • more expensive to form than a torispherical head,

      • but may allow a reduction in material thickness as the strength is greater

    • The I.C.R is 0.8 of the O.D of the head

    • The I.K.R is 0.154 of the O.D of the head

    • The S.F =10mm and 30mm


Head configurations2

HEAD Configurations

  • Hemispherical

    • allow more pressure than any other head

    • most expensive to form

    • The depth of the head is half of the diameter.


Head configurations3

HEAD Configurations

  • Shallow Head

    • commonly used atmospheric tanks

    • not suitable for pressure vessels

    • I.C.R =1.5 to 2.0 times the I.D of the head

    • I.K.R = 32mm, 51mm or 76mm (depending on the diameter and customer requirements)

    • The S.F =10mm and 30mm


Head configurations4

HEAD Configurations

  • Cones for Pressure Vessels

    • The maximum internal apex angle for cones =120O

    • The I.K.R = 6% of the inside diameter of the vessel

    • The S.F =10mm and 30mm


Head configurations5

HEAD Configurations

  • Flat.

    • A flat end with a knuckled outer edge

    • used as bases on vertical atmospheric tanks and lids for smaller tanks

    • The I.K.R =25mm, 32mm and 51mm

    • The S.F. = 10mm and 30mm


Head configurations6

HEAD Configurations

  • Dish.

    • used for atmospheric tanks and vessels and for bulk heads or baffles inside horizontal tanks or tankers

    • Typically the I.C.R is equal to the diameter


Head thickness

HEAD THICKNESS

Standard Ellipsoidal

Hemispherical

Standard Dished

where

L = crown radius in inches = Do – 6

Kr= knuckle radius = 0.06 Do


Head thickness1

HEAD THICKNESS

Standard Dished

  • Values for W or dished heads

    Kr/LW

    0.061.8

    0.071.7

    0.081.65

    0.091.6

    0.101.55

    0.111.50

    0.121.47

    0.131.44

    0.141.41


Head thickness2

HEAD THICKNESS

Standard Dished

  • Values for W or dished heads

    Kr/LW

    0.151.40

    0.161.38

    0.171.37

    0.181.35

    0.191.32

    0.201.30

    0.251.25

    0.501.12

    1.01.0


Head thickness3

HEAD THICKNESS

Flat Heads

*Lap Welded w/ or w/o Plug Welds:

*Single or Double V Butt Welded

*Cut from Solid PlateStandardDished


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