ASME Section VIII div 2 2010. ASME Boiler and Pressure Vessel Code. Alternative Rules

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2010 SECTION VIII, DIVISION 2

5-39

()

aTR

stress amplitude from the applicable design fatigue curve (see Annex 3.F, paragraph 3.F.1.2)

evaluated at

cycles.

elastically calculated bending stress at the point under evaluation for the

k cycle at the m

point.

elastically calculated bending stress at the point under evaluation for the

k cycle at the n

point.

von Mises stress.

,ek

von Mises stress for the

k loading condition.

are the principal stress components.

,ij k

stress tensor at the point under evaluation for the

k cycle at the m point.

ij k

stress tensor at the point under evaluation for the

k cycle at the m point.

ij k

stress tensor at the point under evaluation for the

k cycle at the n point.

ij k

stress tensor due to local thermal stress at the location and time point under evaluation for

the

k cycle.

elastically calculated membrane stress at the point under evaluation for the

cycle at the m

point.

elastically calculated membrane stress at the point under evaluation for the

k cycle at the n

point.

max,k

maximum stress in the

k cycle.

mean,k

mean stress in the

k cycle.

min,k

minimum stress in the

k cycle.

principal stress in the 1-direction.

principal stress in the 2-direction.

principal stress in the 3-direction.

1,k

principal stress in the 1-direction for the

k loading condition.

2,k

principal stress in the 2-direction for the

k loading condition.

3,k

principal stress in the 3-direction for the

k loading condition.

t minimum wall thickness in the region under consideration, or the thickness of the vessel, as

applicable.

ess

t structural stress effective thickness.

t minimum wall thickness associated with

elastically calculated bending component of shear stress distribution at the point under

evaluation for the

cycle at the m point.

elastically calculated bending component of shear stress distribution at the point under

evaluation for the

cycle at the n point.

2010 SECTION VIII, DIVISION 2

5-40

elastically calculated membrane component of shear stress distribution at the point under

evaluation for the

k cycle at the m point.

elastically calculated membrane component of shear stress distribution at the point under

evaluation for the

k cycle at the n point.

UTS minimum specified ultimate tensile strength at room temperature.

w required with of attachment.

maximum general primary membrane stress divided by the yield strength.

minimum specified yield strength at room temperature.

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2010 SECTION VIII, DIVISION 2

5-41

5.14 Tables

Table 5.1 – Loads And Load Cases To Be Considered In A Design

Loading Condition Design Loads

Pressure Testing

1. Dead load of component plus insulation, fireproofing, installed

internals, platforms and other equipment supported from the

component in the installed position.

2. Piping loads including pressure thrust

3. Applicable live loads excluding vibration and maintenance live loads.

4. Pressure and fluid loads (water) for testing and flushing equipment

and piping unless a pneumatic test is specified.

5. Wind loads

Normal Operation

1. Dead load of component plus insulation, refractory, fireproofing,

installed internals, catalyst, packing, platforms and other equipment

supported from the component in the installed position.

2. Piping loads including pressure thrust

3. Applicable live loads.

4. Pressure and fluid loading during normal operation.

5. Thermal loads.

Normal Operation plus

Occasional (note: occasional

loads are usually governed by

wind and earthquake;

however, other load types

such as snow and ice loads

may govern, see ASCE-7)

1. Dead load of component plus insulation, refractory, fireproofing,

installed internals, catalyst, packing, platforms and other equipment

supported from the component in the installed position.

2. Piping loads including pressure thrust

3. Applicable live loads.

4. Pressure and fluid loading during normal operation.

5. Thermal loads.

6. Wind, earthquake or other occasional loads, whichever is greater.

7. Loads due to wave action

Abnormal or Start-up

Operation plus Occasional

(see note above)

1. Dead load of component plus insulation, refractory, fireproofing,

installed internals, catalyst, packing, platforms and other equipment

supported from the component in the installed position.

2. Piping loads including pressure thrust

3. Applicable live loads.

4. Pressure and fluid loading associated with the abnormal or start-up

conditions.

5. Thermal loads.

6. Wind loads.

2010 SECTION VIII, DIVISION 2

5-42

Table 5.2 – Load Descriptions

Design Load Parameter Description

Internal and external specified design pressure

Static head from liquid or bulk materials (e.g. catalyst)

Dead weight of the vessel, contents, and appurtenances at the location of

interest, including the following:

• Weight of vessel including internals, supports (e.g. skirts, lugs, saddles,

and legs), and appurtenances (e.g. platforms, ladders, etc.)

• Weight of vessel contents under operating and test conditions

• Refractory linings, insulation

• Static reactions from the weight of attached equipment, such as motors,

machinery, other vessels, and piping

• Appurtenance Live loading

• Effects of fluid momentum, steady state and transient

Earthquake loads (see ASCE 7 for the specific definition of the earthquake

load, as applicable)

Wind Loads

Is the pressure test wind load case. The design wind speed for this case shall

be specified by the Owner-User.

Snow Loads

Is the self-restraining load case (i.e. thermal loads, applied displacements).

This load case does not typically affect the collapse load, but should be

considered in cases where elastic follow-up causes stresses that do not relax

sufficiently to redistribute the load without excessive deformation.

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2010 SECTION VIII, DIVISION 2

5-43

Table 5.3 – Load Case Combinations and Allowable Stresses for an Elastic Analysis

Design Load Combination (1) Allowable Stress

PP D++

Determined based on the Stress

Category shown in Figure 5.1

PP DL+++

PP DLT++++

PP DS+++

()

0.6 0.7DWor E+ (2)

()

0.9 0.7

PP D Wor E+++

()

0.9 0.75 0.75

PP D LT S+++ + +

()

0.9 0.75 0.7 0.75 0.75

PP D Wor E L S+++ + +

Notes

1) The parameters used in the Design Load Combination column are defined in Table 5.2.

2) This load combination addresses an overturning condition. If anchorage is included in the design,

consideration of this load combination is not required

3) Loads listed herein shall be considered to act in the combinations described above; whichever

produces the most unfavorable effect in the component being considered. Effects of one or more loads

not acting shall be considered.

2010 SECTION VIII, DIVISION 2

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Table 5.4 – Load Case Combinations and Load Factors for a Limit Load Analysis

Design Conditions

Criteria Required Factored Load Combinations

Global Criteria

()

1.5

PP D++

()

1.3 1.7 0.54

PP DT L S+++ + +

()

(

)

1.3 1.7 1.1 0.86

PP D S Lor W++ + +

()

1.3 1.7 1.1 0.54

PP D W L S++ + + +

()

1.3 1.1 1.1 0.21

PP D E L S++ + + +

Local Criteria Per Table 5.5

Serviceability Criteria Per User’s Design Specification, if applicable, see Table 5.5

Hydrostatic Test Conditions

Global Criteria

()

max 1.43, 1.25 2.6

PP D W

⎡⎤

⎛⎞

⋅++ +

⎜⎟

⎢⎥

⎝⎠

⎣⎦

Serviceability Criteria Per User’s Design Specification, if applicable.

Pneumatic Test Conditions

Global Criteria

()

1.15 2.6

PP D W

⎛⎞

⋅++ +

⎜⎟

⎝⎠

Serviceability Criteria Per User’s Design Specification, if applicable.

Notes:

1) The parameters used in the Design Load Combination column are defined in Table 5.2.

2) See paragraph 5.2.3.4 for descriptions of global and serviceability criteria.

S is the allowable membrane stress at the design temperature.

S is the allowable membrane stress at the pressure test temperature.

5) Loads listed herein shall be considered to act in the combinations described above; whichever

produces the most unfavorable effect in the component being considered. Effects of one or more

loads not acting shall be considered.

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2010 SECTION VIII, DIVISION 2

5-45

Table 5.5 – Load Case Combinations and Load Factors for an Elastic-Plastic Analysis

Design Conditions

Criteria Required Factored Load Combinations

Global Criteria

(

)

2.4

PP D++

(

)

2.1 2.7 0.86

PP DT L S+++ + +

(

)

(

)

2.1 2.7 1.7 1.4

PP D S Lor W++ + +

(

)

2.1 2.7 1.7 0.86

PP D W L S++ + + +

(

)

2.1 1.7 1.7 0.34

PP D E L S++ + + +

Local Criteria

()

1.7

PP D++

Serviceability Criteria Per User’s Design Specification, if applicable, see paragraph 5.2.4.3.b.

Hydrostatic Test Conditions

Global and Local Criteria

()

max 2.3, 2.0

PP D W

⎡⎤

⎛⎞

⋅++ +

⎜⎟

⎢⎥

⎝⎠

⎣⎦

Serviceability Criteria Per User’s Design Specification, if applicable.

Pneumatic Test Conditions

Global and Local Criteria

()

1.8

PP D W

⎛⎞

⋅++ +

⎜⎟

⎝⎠

Serviceability Criteria Per User’s Design Specification, if applicable.

Notes:

1) The parameters used in the Design Load Combination column are defined in Table 5.2.

2) See paragraph 5.2.4.3 for descriptions of global and serviceability criteria.

S is the allowable membrane stress at the design temperature.

S is the allowable membrane stress at the pressure test temperature.

5) Loads listed herein shall be considered to act in the combinations described above; whichever

produces the most unfavorable effect in the component being considered. Effects of one or more

loads not acting shall be considered.

2010 SECTION VIII, DIVISION 2

5-46

Table 5.6 – Examples Of Stress Classification

Vessel Component Location Origin of Stress Type of Stress Classification

Any shell including

cylinders, cones,

spheres and formed

heads

Shell plate remote

from discontinuities

Internal pressure General membrane

Gradient through

plate thickness

Axial thermal

gradient

Membrane

Bending

Near nozzle or other

opening

Net-section axial

force and/or bending

moment applied to

the nozzle, and/or

internal pressure

Local membrane

Bending

Peak (fillet or corner)

Any location Temperature

difference between

shell and head

Membrane

Bending

Shell distortions

such as out-of-

roundness and

dents

Internal pressure

Membrane

Bending

Cylindrical or conical

shell

Any section across

entire vessel

Net-section axial

force, bending

moment applied to

the cylinder or cone,

and/or internal

pressure

Membrane stress

averaged through

the thickness,

remote from

discontinuities;

stress component

perpendicular to

cross section

Bending stress

through the

thickness; stress

component

perpendicular to

cross section

Junction with head

or flange

Internal pressure

Membrane

Bending

Dished head or

conical head

Crown Internal pressure

Membrane

Bending

Knuckle or junction

to shell

Internal pressure

Membrane

Bending

[note (1)]

Flat head Center region Internal pressure

Membrane

Bending

Junction to shell Internal pressure

Membrane

Bending

Q [note (2)]

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2010 SECTION VIII, DIVISION 2

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Table 5.6 – Examples Of Stress Classification

Vessel Component Location Origin of Stress Type of Stress Classification

Perforated head or

shell

Typical ligament in a

uniform pattern

Pressure Membrane

(averaged through

cross section)

Bending (averaged

through width of

ligament., but

gradient through

plate)

Peak

Isolated or atypical

ligament

Pressure

Membrane

Bending

Peak

Nozzle

(see paragraph 5.6)

Within the limits of

reinforcement given

by paragraph 4.5

Pressure and

external loads and

moments including

those attributable to

restrained free end

displacements of

attached piping

General membrane

Bending (other than

gross structural

discontinuity

stresses) averaged

through nozzle

thickness

Outside the limits of

reinforcement given

by paragraph 4.5

Pressure and

external axial, shear,

and torsional loads

including those

attributable to

restrained free end

displacements of

attached piping

General Membrane

Pressure and

external loads and

moments, excluding

those attributable to

restrained free end

displacements of

attached piping

Membrane

Bending

Pressure and all

external loads and

moments

Membrane

Bending

Peak

Nozzle wall Gross structural

discontinuities

Membrane

Bending

Peak

Differential

expansion

Membrane

Bending

Peak

Cladding Any Differential

expansion

Membrane

Bending

Any Any Radial temperature

distribution [note (3)]

Equivalent linear

stress [note (4)]

2010 SECTION VIII, DIVISION 2

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Table 5.6 – Examples Of Stress Classification

Vessel Component Location Origin of Stress Type of Stress Classification

Nonlinear portion of

stress distribution

Any Any Any Stress concentration

(notch effect)

Notes:

1. Consideration shall be given to the possibility of wrinkling and excessive deformation in vessels with

large diameter-to-thickness ratio.

2. If the bending moment at the edge is required to maintain the bending stress in the center region

within acceptable limits, the edge bending is classified as

P ; otherwise, it is classified as Q .

3. Consider possibility of thermal stress ratchet.

4. Equivalent linear stress is defined as the linear stress distribution that has the same net bending

moment as the actual stress distribution.

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