Public Review Draft 2048

7/26/2019 Public Review Draft 2048

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B31T - A351 number assignment Record 13-1512

A 351 Grade CF8C, CF10MC, CH8, CH10, CN7M SS -325 Stainless steels C ...A 351 Grade HT30 SS -325 Stainless steels C 1A 351 Grade CF3, CF3A, CF3M, CF8, CF8A, CF8M SS -425 Stainless steels C ...

SS -60

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B31T - A351 number assignment

SS -425 A 351 Grade CF3, CF3A, CF3M, CF8, CF8A, CF8M C ...

SS -325 A 351 Grade CF8C, CF10MC, CH8, CH10, CN7M C ...SS -325 A 351 Grade HT30 C 1

SS -60 A 351 Grade CD3M-W-Cu-N, CE8MN C ...

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B31T - A351 number assignment Record 13-1512

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- num er ass gnment

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Record 13-1512

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A 671 Grade CC65 (A516 Gr 65), CC70 (A516 Gr 70) - Not Normalized CS B Carbon steels P 8A 671 Grade CC60 (A516 Gr 60), CC65 (A516 Gr 65),- Normalized CS D Carbon steels P 8

CC70 (A516 Gr 70) - Normalized

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A 672 Grade C65 (A516 Gr 65), C70 (A516 Gr 70) - Not Normalized CS B Carbon steels P 8A 672 Grade C55 (A516 Gr 55), C60 (A516 Gr 60),- Normalized CS D Carbon steels P 8

C65 (A516 Gr 65), C70 (A516 Gr 70) - Normalized

B31T - A671, A672 number assignment Record 13-1516

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CS B A 671 Grade CC65 (A516 Gr 65), CC70 (A516 Gr 70) P 3

CS D A 671 Grade CC60(A516 Gr 60), CC65 (A516 Gr 65), CC70 (A516 Gr 70) P 3

CS B A 672 Grade C65 (A516 Gr 65), C70 (A516 Gr 70) P 3

CS D A 672 Grade C55(A516 Gr 55), C60(A516 Gr 60), C65 (A516 Gr 65), C70 (A516 Gr 70) P 3


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Tracking Number 13-1517 (ASME B31T) Proj Mgr: Chip EskridgeJacobs Engineering Group

Proposal:

AddlanguagetoPara4.4.2andasaGENERALNOTEtoTable4.4.21toremovethe

temperatureadjustment(i.e.temperaturereduction)forImpactTestingSubsized

specimensofductilematerialsdownto320F.

Rationale:

ThepurposefortemperaturereductionofsubsizedCharpysistoadjustfortheshiftinthe

ductiletobrittletransitioncurvethatoccurswithsmallerspecimens. However,forP6,P7,

andP8material,aDTBtransitiondoesntexistandthecode(B31.3)useslateral

expansionasthecriteriawithnotemperatureadjustmentforsubsizespecimens.

ColorScheme:

Textin

Red/Underlined

are

proposed

additions.

Texthilitedinyellow andBlueisforattentiononlytothe

readerandbookeditor.

Current Code 2010 Proposed Change

4.4.2 For Materials With Thickness Less Than10 mm (0.394 in.).Where the largest attainable CVNspecimen has a width along the notch of at least 80% of

the material thickness, the Charpy test of such a

specimen shall be conducted at a temperature not

warmer than the design minimum temperature. Where

the largest possible test specimen has a width along the

notch of less than 80% of the material thickness, the

test shall be conducted at a temperature colder than the

design minimum temperature by an amount equal to

the difference (referring to Table 4.4.2-1) between the

temperature reduction corresponding to the actual

material thickness and the temperature reduction

corresponding to the Charpy specimen width actually

tested.

Test Temperature p(Design Minimum Temperature) +

(Temperature Reduction Based on Actual Material

Thickness) (Temperature Reduction Based on

Charpy Impact Specimen Width)

For example, if the design minimum temperature is

20C, the actual material thickness is 6 mm and the

specimen is 4 mm, the test temperature is (20) + 8.3

16.7 p 28.4C.

4.4.2 For Materials With Thickness Less Than10 mm (0.394 in.).Where the largest attainable CVNspecimen has a width along the notch of at least 80% of

the material thickness, the Charpy test of such a

specimen shall be conducted at a temperature not

warmer than the design minimum temperature. Where

the largest possible test specimen has a width along the

notch of less than 80% of the material thickness, the test

shall be conducted at a temperature colder than the

design minimum temperature by an amount equal to

the difference (referring to Table 4.4.2-1) between the

temperature reduction corresponding to the actual

material thickness and the temperature reduction

corresponding to the Charpy specimen width actually

tested. These temperature reduction criteria donot apply when Table 4.5.1-1 specif ies lateral

expansion for minimum required values.

Test Temperature p(Design Minimum Temperature) +

(Temperature Reduction Based on Actual Material

Thickness) (Temperature Reduction Based on

Charpy Impact Specimen Width)

For example, if the design minimum temperature is

20C, the actual material thickness is 6 mm and the

specimen is 4 mm, the test temperature is (20) + 8.3

16.7 p 28.4C.


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CurrentCode2010andProposedChangeinRED underlinebelow.

General Note: These temperature reduction cr iteria do not apply when Table 4.5.1-1 specifieslateral expansion for minimum required values.

ddENERAL

OTE before

OTE (1)


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Explanation,Background:

The proposed change is consistentwith B31.3 criteria (hilited in YELLOW below), Table 323.3.4

GENERALNOTE. Thistableisprovidedforinfoonlytothereaderandbookeditor.


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Record 13-1521


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Record 13-1521


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ASME B31T-2010

lower critical temperature: the temperature at which thefirst phase change occurs when heating a metal.

NDT temperature: the nil ductility transition temperature.

stress ratio:the ratio of the design stress to an allowablestress. (See para. 3.6.2.)

T-number:a number assigned to a group of similar mate-rials with similar low-temperature requirements. Thenumber consists of the material type, a temperaturecharacteristic, and possibly a suffix.

3 LOW-TEMPERATURE RANGES ANDREQUIREMENTS

3.1 Low-Temperature Service Requirements

Low-temperature service requirements are containedin Table 3.1-1. These requirements are established forT-number groups of materials with similar require-ments. In addition to T-number group, in some cases

requirements are dependent on thickness and/or othercharacteristics as listed in Table 3.1-1.

3.2 Material Groupings (Column 1 of Table 3.1-1)

Material T-number groups for each covered materialspecification are provided in Table 3.2-1. (In addition, atable sorted by material type and T-number group thatlists all materials in each T-number group is providedin Mandatory Appendix III.) In determining the applica-ble T-number group for a material from the table, consid-eration shall be given to the material specification,grade, and any other variables as established in thenotes. The table separates the materials into types (car-

bon steel, low alloy steel, etc.), and the group numberis representative of the low-temperature service limitfor the material; however, the low-temperature servicelimit may vary based on the design and fabricationrequirements. Low-temperature service limits shall bedetermined from Table 3.1-1. An (A) in the T-numbergroup [e.g., CS 20(A)] indicates that materials of thatgroup may not be used at temperatures colder than thegroup number [e.g., 20F (29C)].

3.3 Nominal Thickness and Notes (Columns 2 and 3of Table 3.1-1)

For material T-number groups where the low-

temperature suitability varies significantly according tothe thickness, a thickness is listed in column 2 ofTable 3.1-1. Note that the thickness is the nominal thick-ness as defined in the code or specification referencingthis Standard. The variation based on thickness appliesto carbon steel T-number groups CS A, CS B, CS C,and CS D where Table 3.1-1 lists thickness at each 10Fincrement. When it is desired to refine the influenceof the thickness, Mandatory Appendix I provides thecontinuous curves and tables that can be used at inter-mediate values or greater thickness. Since the nominal

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thicknesses in Table I-1 of Mandatory Appendix I aregenerally derived based on uniform increments of tem-perature, the tables do not contain uniform incrementsof thickness. Again, the continuous curves in MandatoryAppendix I should be consulted for the precise values.

For material T-number groups where the low-

temperature suitability is dependent upon some otherfactor, those factors are given in the notes listed in col-umn 3 of Table 3.1-1.

3.4 Low-Temperature Service Limit (Column 4 ofTable 3.1-1)

Column 4, the first temperature column in Table 3.1-1,is the low-temperature service limit. If the design min-imum temperature is equal to or warmer than this value,then low-temperature requirements do not apply. Mate-rial within a group may be used at this temperature ortemperatures warmer than this limit without imposingany of the requirements of this Standard. This limit con-

siders material properties and the influence of fabrica-tion processes on the material properties.

3.5 Material Requirements for Low-TemperatureService (Columns 5 and 6 of Table 3.1-1)

Column 5 lists the minimum material permitted tem-perature. When a temperature is listed, this is the designminimum temperature permitted for the material groupregardless of impact testing or any other requirementsexcept as permitted by column 18.

Column 6 is the minimum temperature withoutimpact testing for the material. If the design minimumtemperature is equal to or warmer than this value, the

material does not require impact testing. If the designminimum temperature is colder than this value, impacttesting of the material in accordance with section 3 isrequired. For carbon steels, this limit might vary withmaterial thickness (T-number groups CS A, CS B, CS C,and CS D) or with stress levels. Additional rows areprovided in the table for thickness variations. Interpola-tion between thicknesses is permitted. A figure and atable for the curves of the variation of temperature withthickness are provided in Mandatory Appendix I andthese may be used as an alternative to the values inTable 3.1-1. Permitted temperature with stress limits areprovided for by utilizing columns 10 through 18 instead

of column 6 as discussed in para. 3.6 below.

3.6 Design Requirements for Low-TemperatureService (Columns 1017 of Table 3.1-1)

3.6.1 Minimum Material Temperature Without ImpactTesting. Columns 10 through 17 list the minimummaterial temperature without impact testing based ondesign stresses and may be used provided

(a) the piping system is subjected to a hydrostatic testat no less than 1.5 times the design pressure

Copyright 2010 by the American Society of Mechanical Engineers.No reproduction may be made of this material without written consent of ASME.

c

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where the applied stress is limitedto 30% of the allowable

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for carbon steels


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ASME B31T-2010

(b) the piping system is not subjected to unevaluatedexternal loads such as maintenance loads, impact loads,and thermal shock

3.6.2 Stress Ratio. The stress ratio is defined as themaximum of the following:

(a) nominal pressure stress (based on minimum pipewall thickness less allowances) divided by the allowablestress at the design minimum temperature.

(b) for piping components with pressure ratings, thepressure for the condition under consideration dividedby th e pres su re ra tin g at th e de si gn mi ni mu mtemperature.

(c) combined longitudinal stress due to pressure,dead weight, and displacement strain (stress intensifica-tion factors are not included in this calculation) dividedby the allowable stress at the design minimum tempera-ture. In calculating longitudinal stress, the forces andmoments in the piping system shall be calculated usingnominal dimensions, and the stresses shall be calculated

using section properties based on the nominal dimen-sions less corrosion,erosion, and mechanical allowances.

In determining thestress ratio, theloadings coincidentwith the metal temperature under consideration maybe used in lieu of maximum design values. Where thereare several low-temperature design conditions, eachshall be evaluated to determine the stress ratio.

The curve used to generate columns 10 through 17 isprovided in Mandatory Appendix II and may be usedas an alternative to columns 10 through 17.

Column 18 lists the minimum low-temperature ser-vice limit achievable by limiting stresses to less than10% of the tensile strength (i.e., SR 0.3) and may be

used without any additional low-temperature servicerequirements. At these stress levels, the design margin isconsidered adequate to prevent a brittle fracture failuremode.

3.7 Fabrication Requirements for Low-TemperatureService (Columns 7, 8, and 9 of Table 3.1-1)

3.7.1 Temperature Limits. Column 7 lists the mini-mum weld permitted temperature. When a temperatureis listed,this is thedesign minimum temperaturepermit-ted for welded construction for this material group,thickness, and notes regardless of impact testing or anyother requirements. Use of material is prohibited at tem-

peratures colder than this temperature unless permittedby column 9.

Column 8 of Table 3.1-1 lists the design minimumtemperature permitted for each material group withoutadditional fabrication requirements. Alternatively, whenstresses are limitedto 30%of allowable, thetemperaturesin column 9 may be used.

When materials are used at temperatures colder thanthose listed in column 8 or 9 as applicable, the weldingand bending and forming procedures shall be qualifiedto verify that they do not result in significant loss of

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material toughness. In addition, weld filler metal shallmeet the impact test requirements of para. 3.7.4.

3.7.2 Welding Procedure Specifications

3.7.2.1 General. When welding procedures arerequired to be qualified with impact testing per

para. 3.7.1, the supplementary essential variables ofASME Section IX are applicable. Impact tests of the weldmetal and heat-affected zone shall be performed inaccordance with the following paragraphs except thatimpact tests of theheat-affected zone are not required for

(a) the qualification for welds in P-Nos. 1 and 3 mate-rials that are postweld heat treated and are made byany process other than electroslag, electrogas, or thermit

(b) the qualification for weld deposit cladding orhard-facing on any base material

(c) that portion of the heat-affected zone associatedwith GTAW root deposits with a maximum of two layersor 5 mm (316 in.) thickness, whichever is less

3.7.2.2 Test Specimens. The weld procedure qual-ification impact test specimens shall be Charpy V-notchspecimens prepared and tested in accordance with therequirements in ASME Section IX. A test shall consistof five specimens, all of which shall be tested at or belowthe design minimum temperature. The highest and low-est values of these specimens shall be disregarded, andthe average value of the three remaining specimens shallequal or exceed the impact value required for the basemetal to be welded in production.

The impact specimen representing the weld depositshall be located so that the longitudinal axis of the speci-

men is at least 0.25tfrom a surface, where t is the thick-ness of the test weld and, where the thickness of thetest assembly permits, not less than 10 mm (38in.) fromthe weld surface of the test assembly. In addition, whenthe postweld heat treatment temperature exceeds themaximum temperature specified by the code referencingthis Standard, and the test assembly is cooled at anaccelerated rate, the longitudinal axis of the specimenshall be a minimum oftfrom the edge of the test assem-bly. The specimen shall be transverse to the longitudinalaxis of the weld with the area of the notch located inthe weld. The length of the notch of the Charpy V-notchspecimen shall be normal to the surface of the weld.

Specimens representing the heat-affected zone shallbe taken from the welding procedure qualification testassemblies in accordance with (a) through (c) below.

(a) If the qualification test material is in the form ofa plate or a forging, the axis of the weld shall be orientedin the direction parallel to the principal direction ofrolling or forging.

(b) The specimens shall be removed from a locationas near as practical to a depth midway between thesurface and center thickness. The coupons for heat-affected zone impactspecimensshall be taken transverse

13-2013 Rev. 5/29/2015

instead of the values in column 8

Note - Moved tothe end of 3.6.1

The curve used to generate columns 10through 17 is provided in MandatoryAppendix II and may be used as analternative to columns 10 through 17.

Column 18 lists the minimum low-temperature service limit achievable bylimiting stresses to less than 10% of thetensile strength (i.e., SR 0.3) and may bused without any additional low-temperature service requirements. Atthese stress levels, the design margin isconsidered adequate to prevent a brittlefracture failure mode. The low-

temperature service limit listed in column18 may be used in lieu of that listed incolumn 4 when the stress ratio 0.3.

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