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

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2010 SECTION VIII, DIVISION 2

4-385

given by Equation (4.18.122).

()

(

)

61 *

sss os

sb s s s

sss

kaP ah

tEtEh

σβδ

⎡⎤

−

⎛⎞

⎢⎥

=++ +

⎜⎟

⎢⎥

⎝⎠

⎢⎥

⎣⎦

(4.18.230)

()

(

)

61 *

* 2

ccc oc

cb c c t

ccc

kaP ah

tEtEh

σβδ

⎡⎤

−

⎛⎞

⎢⎥

=+− +

⎜⎟

⎢⎥

⎝⎠

⎢⎥

⎣⎦

(4.18.231)

4.18.9.7 Calculation Procedure for Simply Supported Floating Tubesheets

4.18.9.7.1 Scope

This procedure describes how to use the rules of 4.18.9.4 when the effect of the stiffness of the integral

channel and/or shell is not considered.

4.18.9.7.2 Conditions of Applicability

This calculation applies only when the tubesheet is integral with the shell or channel (Configurations a,b, c, e,

f,and A.)

4.18.9.7.3 Calculation Procedure

The calculation procedure outlined in 4.18.9.4 shall be performed accounting for the following modifications;

a) Perform STEPs 1 through 9.

b) Perform STEP 10 except as follows:

1) The shell (Configuration a,b,and c) is not required to meet a minimum length requirement.

2) The channel (Configurations a, e, f,and A) is not required to meet a minimum length requirement.

3) Acceptance Criteria

i) Configuration a: If

PS s

≤

and

,cPSc

≤

, then the shell and channel are acceptable.

Otherwise increase the thickness of the overstressed component(s) (shell and/or channel)

and return to STEP 1.

ii) Configuration b and c : If

PS s

≤

then the shell is acceptable. Otherwise increase the

thickness of the shell and return to STEP 1.

iii) Configuration e, f and A: If

,cPSc

≤

, then the channel is acceptable. Otherwise increase

the thickness of the channel and return to STEP 1.

c) Do not perform STEP 11

d) Repeat STEPs 1 - 7 for loading cases 1 - 3, with the following changes to STEP 2 until the tubesheet

stress criteria have been met:

1) Configurations a, b, and c:

0, 0, 0, 0

ssss

λδ

===.

2) Configurations a, e, f, and A: 0, 0, 0, 0

cccc

λδ

===.

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4.18.10 Tube-to-Tubesheet Welds

4.18.10.1 Scope

These rules provide a basis for establishing weld sizes and allowable joint loads for full strength and partial

strength tube-to-tubesheet welds.

4.18.10.2 Definitions

a) Full Strength Weld – A full strength tube-to-tubesheet weld is one in which the design strength is equal

to or greater than the axial tube strength,

. When the weld in a tube-to-tubesheet joint meets the

requirements of paragraph 4.18.10.3, it is a full strength weld and the joint does not require qualification

by shear load testing. Such a weld also provides tube joint leak tightness.

b) Partial Strength Weld – A partial strength weld is one in which the design strength is based on the

mechanical and thermal axial tube loads (in either direction) that are determined from the actual design

conditions. The maximum allowable axial load of this weld may be determined in accordance paragraph

4.18.10.4 or Annex 4.C. When the weld in a tube-to-tubesheet joint meets the requirements of

paragraph 4.18.10.4, it is a partial strength weld and the joint does not require qualification by shear

load testing. Such a weld also provides tube joint leak tightness.

c) Seal Weld – A tube-to-tubesheet seal weld is one used to supplement an expanded tube joint to ensure

leak tightness. Its size has not been determined based on axial tube loading.

4.18.10.3 Full Strength Welds

Full strength welds shown in Figure 4.18.13 shall conform to the following requirements.

a) The size of a full strength weld shall be determined in accordance with paragraph 4.18.10.5.

b) The maximum allowable axial load in either direction on a tube-to-tubesheet joint with a full strength

weld shall be determined as follows.

1) For loads due to pressure-induced axial forces,

max t

2) For loads due to thermally-induced or pressure plus thermally-induced axial forces:

max t

LF= for welded tube-to-tubesheet joints where the thickness through the weld throat

is less than the nominal tube wall thickness

t .

ii)

max

LF= for welded tube-to-tubesheet joints where the thickness through the weld throat

is greater than or equal to the nominal tube wall thickness

t .

4.18.10.4 Partial Strength Welds

Partial strength welds shown in Figure 4.18.13 shall conform to the following requirements.

a) The size of a partial strength weld shall be determined in accordance with paragraph 4.18.10.5.

b) The maximum allowable axial load in either direction on a tube-to-tubesheet joint with a partial strength

weld shall be determined as follows.

1) For loads due to pressure-induced axial forces,

max

LFF

, but not greater than

F .

2) For loads due to thermally-induced or pressure plus thermally-induced axial forces:

max

LFF=+ but not greater than

F , for welded tube-to-tubesheet joints where the

thickness through the weld throat is less than the nominal tube wall thickness

t .

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ii)

()

max

LFF=+ but not greater than 2

F , for welded tube-to-tubesheet joints where the

thickness through the weld throat is greater than or equal to the nominal tube wall thickness

t .

4.18.10.5 Weld Size Design Equations

a) The size of tube-to-tubesheet strength welds shown in Figure 4.18.13 shall conform to the following

requirements

1) For fillet welds shown in Figure 4.18.13 Sketch (a):

i) Calculate the minimum required length of the fillet weld leg.

() ()

0.75 2.73 0.75

ro owdo

adtdtffd=+−− (4.18.232)

ii) For full strength welds,

[

]

max ,

aat≥ .

iii) For partial strength welds,

aa≥ .

2) For groove welds shown in Figure 4.18.13 Sketch (b):

i) Calculate the minimum required length of the groove weld leg.

() ()

0.75 1.76 0.75

ro owdo

adtdtffd=+−−

(4.18.233)

ii) For full strength welds,

[

]

max ,

aat≥ .

iii) For partial strength welds,

aa≥ .

3) For combined groove and fillet welds shown in Figure 4.18.13 Sketch (c) where

a is equal to

a :

i) Calculate the minimum required length of the combined weld legs.

() ()

2 0.75 1.07 0.75

roowdo

adtdtffd

⎡⎤

=+−−

⎢⎥

⎣⎦

(4.18.234)

ii) For full strength welds,

[

]

max ,

aat≥ .

iii) For partial strength welds,

aa≥ .

iv) Calculate

a and

a using the following equations.

a =

(4.18.235)

a =

(4.18.236)

4) For combined groove and fillet welds shown in Figure 4.18.13 Sketch (d) where

a is not equal to

a ,

a shall be determined as follows:

2010 SECTION VIII, DIVISION 2

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i) Choose

a and calculate the minimum required length of the fillet weld leg.

() ()

0.75 2.73 0.75

ro owdfo

adtdtfffd=+−− (4.18.237)

ii) For full strength welds

(

)

max ,

crg

aaat

⎡

⎤

≥+

⎣

⎦

iii) For partial strength welds

(

)

crg

aaa≥+.

iv) Calculate

a using the following equation.

aaa=− (4.18.238)

b) In weld strength factors used in subparagraph a) above shall be calculated using the following

equations.

1.0

for full strength welds= (4.18.239)

for partial strength welds

= (4.18.240)

=−

(4.18.241)

(4.18.242)

where

()

0.55 0.67

fo fw

FadaS

=+ (4.18.243)

()

0.85 0.67

go gw

FadaS

=+ (4.18.244)

()

toa

FtdtS

=− (4.18.245)

4.18.11 Bellows Expansion Joints

Bellows expansion joints shall be designed in accordance with paragraph 4.19.

4.18.12 Flanged-and-Flued or Flanged-Only Expansion Joints

4.18.12.1 Design

Flanged-and-Flued or Flanged-Only expansion joints shall be designed in accordance with Part 5. The

design considerations (i.e. load case combinations) in paragraph 4.18.8.3 shall be considered in the analysis.

4.18.12.2 Fabrication

The following requirements shall be met in the fabrication of expansion joint flexible elements.

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a) All welded joints shall comply with the requirements of Part 6.

b) All longitudinal and circumferential weld seams shall be butt-type full penetration welds; Type 1 welds in

accordance with paragraph 4.2.

c) Longitudinal welds shall be ground flush and smooth on both inside and outside surfaces prior to being

formed into expansion elements.

d) Other than the shell attachment welds and flange welds, no circumferential welds are permitted in the

fabrication of flexible elements, i.e., inner torus, annular plate, outer torus, unless the welds are ground

flush and fully radiographed.

e) Flexible elements shall be attached by full penetration circumferential welds.

f) Nozzles, backing strips, clips or other attachments shall not be located in highly stressed areas of the

expansion joint, i.e. inner torus, annular plate, and outer torus.

4.18.12.3 Examination

The following examinations are required to verify the integrity of expansion joints.

a) All expansion joint flexible elements shall be visually examined and found to be free of unacceptable

imperfections, such as notches, crevices, weld spatter, etc., which may serve as points of local stress

concentration. Suspect surface areas shall be further examined by liquid penetrant or magnetic particle

examination.

b) Longitudinal welds shall be fully radiographed in accordance with Part 7. All full penetration butt-type

welds shall be examined 100% on both sides by liquid penetrant or magnetic particle examination after

forming.

c) The circumferential welds within the expansion joint and attaching the expansion joint to the shell shall

be examined 100% on both sides, where accessible, by liquid penetrant or magnetic particle

examination. The accessibility of welds shall be subject to the acceptance of the Inspector.

4.18.12.4 Pressure Test Requirements

The pressure testing requirements for expansion joints shall be as follows.

a) The completed expansion joint shall be subject to a pressure test in accordance with paragraph 4.1.6.2

and Part 8. The pressure testing of an expansion joint may be performed as part of the final vessel

pressure test, provided the joint is accessible for inspection during pressure testing.

b) Expansion joint restraining elements shall also be pressure tested in accordance with paragraph 4.1.6.2

and Part 8 as a part of the initial expansion joint pressure test or as part of the final vessel pressure test

after installation of the joint.

c) In addition to inspecting the expansion joint for leaks during the pressure test, expansion joints shall be

inspected before, during, and after the pressure test for visible permanent distortion.

4.18.12.5 Marking and Reports

a) The expansion joint Manufacturer, whether the vessel Manufacturer or a parts Manufacturer, shall have

a valid ASME Code U2 Certificate of Authorization and shall complete the appropriate Data Report in

accordance with Part 2.

b) The Manufacturer responsible for the expansion joint design shall include the following additional data

and statements on the appropriate Data Report.

1) Axial movement (+ and -), associated design life in cycles, and associated loading condition, if

applicable;

2) Spring rate; and

3) The expansion joint has been constructed to the rules of this paragraph.

2010 SECTION VIII, DIVISION 2

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c) A parts Manufacturer shall identify the vessel for which the expansion joint is intended on the Partial

Data Report.

d) Markings shall not be stamped on the flexible elements of the expansion joint.

4.18.13 Pressure Test Requirements

The shell side and the tube side of the heat exchanger shall be subjected to a pressure test in accordance

with paragraph 4.1 and Part 8.

4.18.14 Heat Exchanger Marking and Reports

4.18.14.1 Required Marking

The marking of heat exchangers shall be in accordance with Annex 2.F using the specific requirements for

combination units (multi-chamber vessels). When the markings are grouped in one location and

abbreviations for each chamber are used, they shall be as follows:

a) The chambers shall be abbreviated SHELL for shell side and TUBES for tube side. This abbreviation

shall precede the appropriate design data. For example, use the following for the shell side maximum

allowable working pressure and for the tube side maximum allowable working pressure:

1) SHELL FV&2000 kPa (FV&300 psi) at 280°C (500°F)

2) TUBES 1000 kPa (150 psi) at 175°C (350°F)

b) When the markings are different for each chamber, the chambers shall be abbreviated with a S for shell

side and T for the tube side. For example, use “F-T” for forged construction on the tube side.

4.18.14.2 Supplemental Marking

A supplemental tag or marking shall be supplied on the heat exchanger to caution the user if there are any

restrictions on the design, testing, or operation of the heat exchanger. Supplemental marking shall be

required for, but not limited to, the following:

a) Common Elements – Shell-and-tube heat exchangers are combination units as defined in paragraph

4.1.8.1, and the tubes and tubesheets are common elements. The following marking is required when

the common elements are designed for conditions less severe than the design conditions for which its

adjacent chambers are stamped.

1) Differential Pressure Design – When common elements such as tubes and tubesheets are

designed for a differential design pressure, the heat exchanger shall be marked “Differential

Design” in addition to meeting the requirements of paragraph 4.1.8.1. If the tubes and tubesheets

are designed for a differential pressure of 150 psi, an example of the marking would be:

DIFFERENTIAL DESIGN: TUBES & TUBESHEETS 150 psi

2) Mean Metal Temperature Design – When common elements such as tubes and tubesheets are

designed for a maximum mean metal design temperature that is less than the maximum of the shell

side and tube side design temperatures, the heat exchanger shall be marked “Max Mean Metal

Temp” in addition to meeting the requirements of paragraph 4.1.8.1. If the tubes are designed for a

maximum mean metal temperature of 400˚F, an example of the marking would be:

MAX MEAN METAL TEMP: TUBES 400˚F

b) Fixed Tubesheet Heat Exchangers – Fixed tubesheet heat exchangers shall be marked with a caution

such as follows:

“The Code required pressures and temperatures marked on the heat exchanger relate to the basic

design conditions. The heat exchanger design has been evaluated for specific operating conditions and

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shall be re-evaluated before it is operated at different operating conditions.”

4.18.14.3 Manufacturer’s Data Reports

When common elements such as tubes and tubesheets are designed for a differential pressure or a mean

metal temperature or both, that is less severe than the design conditions for which its adjacent chambers are

stamped, the data for each common element that differs from the data for the corresponding chamber shall

be documented as required in paragraph 4.1.8.2 in the “Remarks” section of the Manufacturer’s Data Report.

4.18.15 Nomenclature

a) Nomenclature for tubesheet flanged extension (paragraph 4.18.5).

G diameter of gasket load reaction

G for U-tube tubesheet Configuration b

G for U-tube tubesheet Configuration e

G for fixed tubesheet Configuration b

G for stationary tubesheet Configuration b of a floating tubesheet exchanger

G for stationary tubesheet Configuration e of a floating tubesheet exchanger

G for floating tubesheet Configuration B of a floating tubesheet exchanger

G or

G for tubesheet Configuration d when applicable (eg. hydrotest)

h gasket moment arm, equal to the radial distance from the center line of the bolts to the line of

the gasket reaction (see paragraph 4.16).

h minimum required thickness of the tubesheet flanged extension.

allowable stress from Annex 3.A for the material of the tubesheet extension at design

temperature (operating condition) or atmospheric temperature (gasket seating), as may apply.

flange design bolt load.

W for gasket seating conditions.

W for operating conditions.

b) Nomenclature for determining tubesheet characteristics (see paragraph 4.18.6)

A total area of untubed lanes,

11 2 2

...

LLL LL LnLn

AUL UL UL

+++ (limited to

4Dp).

A total area enclosed by

C .

c tubesheet corrosion allowance on the tube side, 0

for the uncorroded condition.

C perimeter of the tube layout measured stepwise in increments of one tube pitch from the

center-to-center of the outer most tubes (see Figure 4.18.14).

D equivalent diameter of outer tube limit circle.

diameter of tube hole.

d nominal outside diameter of tubes.

d effective tube hole diameter.

E modulus of elasticity for tubesheet material at tubesheet design temperature.

E modulus of elasticity for tube material at tubesheet design temperature, T .

E effective modulus of elasticity of tubesheet in perforated region, T .

tubesheet thickness.

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h tube side pass partition groove depth.

h effective tube side pass partition groove depth.

, ,...

LL length(s) of untubed lane(s).

l expanded length of tube in tubesheet, 0

≤

≤ . An expanded tube-to-tubesheet joint is

produced by applying pressure inside the tube such that contact is established between the

tube and tubesheet. In selecting an appropriate value of expanded length, the designer shall

consider the degree of initial expansion, differences in thermal expansion, or other factors that

could result in loosening of the tubes within the tubesheet.

tube pitch.

effective tube pitch.

r radius to outermost tube hole center.

allowable stress from Annex 3.A for tubesheet material at tubesheet design temperature, T .

S allowable stress from Annex 3.A for tube material at tubesheet design temperature, T . For a

welded tube or pipe, use the allowable stress for the equivalent seamless product. If the

allowable stress for the equivalent seamless product is not available, then divide the allowable

stress of the welded product by 0.85.

T tubesheet design temperature.

t nominal tube wall thickness.

, ,...

UU center-to-center distance(s) between adjacent tube rows of untubed lane(s), but not to exceed

basic ligament efficiency for shear.

effective ligament efficiency for bending.

effective Poisson’s ratio in perforated region of tubesheet.

tube expansion depth ratio.

c) Nomenclature for the design of U-tube tubesheets (see paragraphs 4.18.7)

A outside diameter of tubesheet

bolt circle diameter (see paragraph 4.16)

D inside channel diameter

D inside shell diameter

modulus of elasticity for tubesheet material at design temperature

E modulus of elasticity for channel material at design temperature

E modulus of elasticity for shell material at design temperature

G midpoint of contact between flange and tubesheet

G diameter of channel gasket load reaction (see paragraph 4.16)

G diameter of shell gasket load reaction (see paragraph 4.16)

h tubesheet thickness

P shell side internal design pressure, for shell side vacuum use a negative value.

P tube side internal design pressure, for tube side vacuum use a negative value.

S allowable stress from Annex 3.A for tubesheet material at tubesheet design temperature

S allowable stress from Annex 3.A for channel material at design temperature. For a welded

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2010 SECTION VIII, DIVISION 2

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tube or pipe, use the allowable stress for the equivalent seamless product. If the allowable

stress for the equivalent seamless product is not available, then divide the allowable stress of

the welded product by 0.85.

S allowable stress from Annex 3.A for shell material at design temperature. For a welded tube

or pipe, use the allowable stress for the equivalent seamless product. If the allowable stress for

the equivalent seamless product is not available, then divide the allowable stress of the welded

product by 0.85.

,yc

S yield strength from Annex 3.D for channel material at design temperature

,ys

S yield strength from Annex 3.D for shell material at design temperature

allowable primary plus secondary stress evaluated using paragraph 5.5.6.1.d for channel

material at design temperature

S allowable primary plus secondary stress evaluated using

paragraph 5.5.6.1.d for shell material at design temperature

t channel thickness

t shell thickness

W channel flange design bolt load for the gasket seating condition (see paragraph 4.16)

W shell flange design bolt load for the gasket seating condition (see paragraph 4.16)

max

W maximum flange design bolt load.

Poisson’s ratio of channel material

Poisson’s ratio of shell material

d) Nomenclature for the design of fixed or floating tubesheets (see paragraphs 4.18.8 and for paragraph

4.18.9)

A outside diameter of tubesheet

a radial channel dimension

a equivalent radius of outer tube limit circle

a radial shell dimension

bolt circle diameter (see paragraph 4.16)

d nominal outside diameter of tubes

D inside channel diameter

D inside diameter of the expansion joint at its convolution height

D inside shell diameter

modulus of elasticity for tubesheet material at

E modulus of elasticity for channel material at

E modulus of elasticity for shell material at

E modulus of elasticity for shell material adjacent to the tubesheet at

E joint efficiency (longituidinal stress) for shell

E modulus of elasticity for tube material at

G midpoint of contact between flange and tubesheet

G diameter of channel gasket load reaction (see paragraph 4.16)

2010 SECTION VIII, DIVISION 2

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G diameter of shell gasket load reaction (see paragraph 4.16)

h tubesheet thickness

J ratio of expansion joint to shell axial rigidity ( 1.0J

if no expansion joint)

K axial rigidity of expansion joint, total force/elongation

k constant accounting for the method of support for the unsupported tube span under

consideration

= 0.6 for unsupported spans between two tubesheets,

= 0.8 for unsupported spans between a tubesheet and a tube support,

= 1.0 for unsupported spans between two tube supports.

l unsupported tube span under consideration

,ll lengths of shell thickness

t adjacent to the tubesheets

L tube length between inner tubesheet faces, 2

LL h

−

L tube length between outer tubesheet faces

N number of tubes

P effective pressure acting on tubesheet

P shell side internal design pressure, for shell side vacuum use a negative value.

P tube side internal design pressure, for tube side vacuum use a negative value.

S allowable stress from Annex 3.A for tubesheet material tubesheet material at T

S allowable stress from Annex 3.A for channel material at

T . For a welded tube or pipe, use

the allowable stress for the equivalent seamless product. If the allowable stress for the

equivalent seamless product is not available, then divide the allowable stress of the welded

product by 0.85.

S allowable stress from Annex 3.A for shell material at

T . For a welded tube or pipe, use the

allowable stress for the equivalent seamless product. If the allowable stress for the equivalent

seamless product is not available, then divide the allowable stress of the welded product by

0.85.

S allowable stress from Annex 3.A for shell material adjacent to the tubesheets at

S maximum allowable longituidinal stress in accordance with 4.4.12.2 for the shell

,,1

S maximum allowable longituidinal stress in accordance with 4.4.12.2 for the shell adjacent to the

tubesheets.

S allowable stress from Annex 3.A for tube material at

T . For a welded pipe or tube, use the

allowable stress from Annex 3.A for the equivalent seamless product. When the allowable

stress for the equivalent seamless product is not available, divide the allowable stress of the

welded product by 0.85.

S yield strength from Annex 3.D for tubesheet material at T

,yc

yield strength from Annex 3.D for channel material at

,ys

S yield strength from Annex 3.D for shell material at

,,1ys

S yield strength from Annex 3.D for shell material adjacent to the tubesheets at

,yt

S yield strength from Annex 3.D for tube material at

S allowable primary plus secondary stress evaluated using paragraph 5.5.6.1.d for tubesheet

material at temperature

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