ASTM A758/A758M-14(2019)

Standard Specification for Wrought-Carbon Steel Butt-Welding Piping Fittings with Improved Notch Toughness

ABSTRACT
This guide covers standard specification for wrought-carbon steel butt-welding seamless or welded fittings specially processed to ensure better notch toughness. Heat treatment shall be required for all types of fittings. Fittings with mandatory radiographic examination of welds shall be included. Cast fittings and fittings formed from all weld metal, shall not be included. Heat or cast analysis shall be conducted wherein the material shall conform to the required chemical components for carbon, manganese, phosphorus, sulfur, silicon, vanadium, chromium, nickel, molybdenum, copper, and lead. The fittings, as represented by tensile test specimens taken subsequent to final heat treatment, shall conform to the specified values of tensile strength, yield strength, and elongation for the applicable grades of steel. Mechanical tests such as tension test and transverse guided weld bend test shall be performed on the fittings.
SCOPE
1.1 This specification covers wrought-carbon steel butt-welding seamless or welded fittings specially processed to ensure better notch toughness than that to be expected in fittings manufactured to the requirements of Specification A234/A234M.  
1.1.1 Included are elbows, caps, tees, reducers, and other type fittings covered by ASME B16.9.  
1.1.2 Heat treatment is required for all fittings.  
1.1.3 Fittings with mandatory radiographic examination of welds are included.  
1.1.4 Supplementary requirements are provided for use when additional testing or examination is desired.  
1.1.5 Cast fittings, and fittings formed from all weld metal, are not included.  
1.2 Several type of fittings are provided, as follows:    
Type  
Heat Treatment
Required  
Weld Seam
Finish (5.3.2)  
Radiography
Required?  
30  
normalize  
UW-35  
no    
31  
normalize  
UW-35  
yes    
32  
normalize  
UW-35 and ground flush  
yes    
40  
normalize and temper  
UW-35  
no    
41  
normalize and temper  
UW-35  
yes    
42  
normalize and temper  
UW-35 and ground flush  
yes    
50  
quench and temper  
UW-35  
no    
51  
quench and temper  
UW-35  
yes    
52  
quench and temper  
UW-35 and ground flush  
yes    
1.3 It shall be the responsibility of the purchaser to determine whether material meeting the requirements of this specification is satisfactory for the service application.  
1.4 This specification is expressed in both inch-pound units and SI units. However, unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units.  
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Nov-2019
• ICS: 23.040.40 - Metal fittings
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.22 - Steel Forgings and Wrought Fittings for Piping Applications and Bolting Materials for Piping and Special Purpose Applications

Relations

• Replaces: ASTM A758/A758M-14 - Standard Specification for Wrought-Carbon Steel Butt-Welding Piping Fittings with Improved Notch Toughness
• Effective Date: 01-Dec-2019
• Refers: ASTM A275/A275M-23 - Standard Practice for Magnetic Particle Examination of Steel Forgings
• Effective Date: 01-Nov-2023
• Refers: ASTM A960/A960M-19a - Standard Specification for Common Requirements for Wrought Steel Piping Fittings
• Effective Date: 01-Nov-2019
• Refers: ASTM A960/A960M-19 - Standard Specification for Common Requirements for Wrought Steel Piping Fittings
• Effective Date: 01-Mar-2019
• Refers: ASTM A234/A234M-18a - Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• Effective Date: 01-Sep-2018
• Refers: ASTM A234/A234M-18 - Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• Effective Date: 01-Mar-2018
• Refers: ASTM A234/A234M-17 - Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• Effective Date: 15-May-2017
• Refers: ASTM A234/A234M-16 - Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• Effective Date: 01-Dec-2016
• Refers: ASTM A960/A960M-16a - Standard Specification for Common Requirements for Wrought Steel Piping Fittings
• Effective Date: 01-Dec-2016
• Refers: ASTM A960/A960M-16 - Standard Specification for Common Requirements for Wrought Steel Piping Fittings
• Effective Date: 01-Jun-2016
• Refers: ASTM A960/A960M-15 - Standard Specification for Common Requirements for Wrought Steel Piping Fittings
• Effective Date: 01-Nov-2015
• Refers: ASTM A960/A960M-14a - Standard Specification for Common Requirements for Wrought Steel Piping Fittings
• Effective Date: 01-Nov-2014
• Refers: ASTM A234/A234M-14 - Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• Effective Date: 01-Oct-2014
• Refers: ASTM A960/A960M-14 - Standard Specification for Common Requirements for Wrought Steel Piping Fittings
• Effective Date: 01-May-2014
• Refers: ASTM A234/A234M-13 - Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• Effective Date: 01-Oct-2013

Overview

ASTM A758/A758M-14(2019) is the international standard specification for wrought-carbon steel butt-welding piping fittings with improved notch toughness. Issued by ASTM International, this standard addresses seamless or welded pipe fittings-such as elbows, caps, tees, and reducers-manufactured with processes that provide better performance under impact loading compared to conventional fittings (such as those specified in ASTM A234/A234M).

This document sets clear requirements for heat treatment, radiographic examination of welds, chemical composition, mechanical property testing, and product marking. The improved notch toughness makes these fittings especially suitable for critical piping applications where enhanced resistance to brittle fracture is needed, such as in low-temperature or high-pressure environments.

Key Topics

• Material Scope: Covers wrought-carbon steel, both seamless and welded, for butt-welding fittings. Cast fittings and all-weld metal fittings are excluded.
• Types of Fittings: Includes commonly used fittings covered by ASME B16.9, such as elbows, tees, reducers, and caps.
• Heat Treatment: Mandatory for all fittings, with processes including normalization, tempering, or quenching and tempering, depending on fitting type.
• Mechanical Requirements: Fittings must meet minimum tensile strength, yield strength, and elongation values as determined by standard tension and weld bend tests after final heat treatment.
• Chemical Composition: Specifies maximum and minimum content levels for elements such as carbon, manganese, silicon, phosphorus, sulfur, and residual elements.
• Quality Assurance: Requires radiographic inspection of welds for certain fitting types, material traceability, certification, and compliance with strict non-destructive examination procedures.
• Supplementary Requirements: Allows for additional customer-specified tests such as Charpy V-notch impact tests, pressure testing, magnetic particle examination, and liquid penetrant inspection.

Applications

ASTM A758/A758M butt-welding fittings are utilized primarily in pipeline systems where enhanced fracture resistance is critical. The improved notch toughness ensures reliability in:

• Low-temperature service: Ideal for industries like oil & gas, chemical processing, or power generation where pipelines may operate under cold conditions.
• High-pressure environments: Suited for applications requiring superior integrity to avoid failures in pressure piping systems.
• Critical infrastructure: Used in refineries, petrochemical plants, and boiler or pressure vessel piping governed by ASME Boiler and Pressure Vessel Code.

With its emphasis on toughness, quality control, and thorough testing, this standard supports safe and reliable piping connections in demanding service conditions.

Related Standards

ASTM A758/A758M references several other standards that provide further guidance or are often used in conjunction:

• ASTM A234/A234M: Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service.
• ASTM A960/A960M: Common Requirements for Wrought Steel Piping Fittings.
• ASME B16.9: Factory-Made Wrought Steel Butt-Welding Fittings.
• ASME Boiler & Pressure Vessel Code, Section VIII, Division 1 and Section IX: Rules for construction of pressure vessels and welding qualifications.
• ASTM E709: Guide for Magnetic Particle Testing.
• ASTM E165: Practice for Liquid Penetrant Testing.
• ASNT SNT-TC-1A: Certification of Nondestructive Testing Personnel.

These related standards ensure a comprehensive approach to product quality, weld integrity, and suitability for critical service.

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Keywords: ASTM A758, wrought-carbon steel fittings, butt-welding piping fittings, improved notch toughness, seamless fittings, welded fittings, heat treatment, radiographic inspection, pressure piping, ASME B16.9, low-temperature service, high-pressure pipelines, mechanical testing, chemical composition.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:A758/A758M −14 (Reapproved 2019)
Standard Specification for
Wrought-Carbon Steel Butt-Welding Piping Fittings with
Improved Notch Toughness
This standard is issued under the fixed designationA758/A758M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope SI units are shown in brackets. The values stated in each
system may not be exact equivalents; therefore, each system
1.1 This specification covers wrought-carbon steel butt-
shall be used independently of the other. Combining values
welding seamless or welded fittings specially processed to
from the two systems may result in non-conformance with the
ensure better notch toughness than that to be expected in
standard.
fittings manufactured to the requirements of Specification
A234/A234M.
1.6 This international standard was developed in accor-
1.1.1 Included are elbows, caps, tees, reducers, and other
dance with internationally recognized principles on standard-
type fittings covered by ASME B16.9.
ization established in the Decision on Principles for the
1.1.2 Heat treatment is required for all fittings.
Development of International Standards, Guides and Recom-
1.1.3 Fittings with mandatory radiographic examination of
mendations issued by the World Trade Organization Technical
welds are included.
Barriers to Trade (TBT) Committee.
1.1.4 Supplementary requirements are provided for use
when additional testing or examination is desired.
2. Referenced Documents
1.1.5 Cast fittings, and fittings formed from all weld metal,
2.1 In addition to those reference documents listed in
are not included.
Specification A960/A960M, the following list of standards
1.2 Several type of fittings are provided, as follows:
apply to this specification:
Heat Treatment Weld Seam Radiography
Type Required Finish (5.3.2) Required?
2.2 ASTM Standards:
A234/A234M Specification for Piping Fittings of Wrought
30 normalize UW-35 no
31 normalize UW-35 yes
Carbon Steel and Alloy Steel for Moderate and High
32 normalize UW-35 and ground flush yes
Temperature Service
40 normalize and temper UW-35 no
A275/A275M Practice for Magnetic Particle Examination of
41 normalize and temper UW-35 yes
42 normalize and temper UW-35 and ground flush yes
Steel Forgings
50 quench and temper UW-35 no
A960/A960M Specification for Common Requirements for
51 quench and temper UW-35 yes
Wrought Steel Piping Fittings
52 quench and temper UW-35 and ground flush yes
E165 Practice for Liquid Penetrant Testing for General
1.3 It shall be the responsibility of the purchaser to deter-
Industry
mine whether material meeting the requirements of this speci-
E709 Guide for Magnetic Particle Testing
fication is satisfactory for the service application.
2.3 ASME Boiler and Pressure Vessel Code (ASME Code):
1.4 This specification is expressed in both inch-pound units
Section VIII, Division 1
and SI units. However, unless the order specifies the applicable
Section IX
“M” specification designation (SI units), the material shall be
furnished to inch-pound units.
2.4 ASME Standard:
B16.9 Standards for Steel Butt-Welding Fittings
1.5 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. Within the text, the
1 2
This specification is under the jurisdiction ofASTM Committee A01 on Steel, For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
A01.22 on Steel Forgings andWrought Fittings for PipingApplications and Bolting Standards volume information, refer to the standard’s Document Summary page on
Materials for Piping and Special Purpose Applications. the ASTM website.
Current edition approved Dec. 1, 2019. Published December 2019. Originally Available from American Society of Mechanical Engineers (ASME), ASME
approved in 1978. Last previous edition approved in 2014 as A758/A758M – 14. International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
DOI: 10.1520/A0758_A0758M-14R19. www.asme.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A758/A758M−14 (2019)
2.5 ASNT Standard: 5.4.3 Types 50, 51, and 52 fittings shall be quenched-and-
SNT-TC-1A Practice for Nondestructive Examination Per- tempered by uniformly heating to a temperature in the austen-
sonnel Qualification and Certification itizing range, but not to exceed 1700 °F [925 °C], and then
quenching in a liquid media from the austenitizing temperature
3. Ordering Information
to a temperature below 800 °F [425 °C]. After quenching, the
fittings shall be reheated to a temperature in the range from
3.1 See Specification A960/A960M.
1100 °F to 1250 °F [595 °C to 675 °C], soaking at that
4. General Requirements
temperature for ⁄2 h minimum per 1 in. [25 mm] of thickness,
but not less than 15 min, and then air-cooled to room
4.1 Product furnished to this specification shall conform to
temperature.
the requirements of Specification A960/A960M, including any
supplementary requirements that are indicated in the purchase
6. Chemical Composition
order. Failure to comply with the requirements of Specification
A960/A960M constitutes non-conformance with this specifi- 6.1 Heat or CastAnalysis—The results shall conform to the
cation. In case of a conflict between the requirements of this requirements for the applicable grade as specified in Table 1.
specificationandSpecificationA960/A960M,thisspecification
6.2 Product Analysis—The purchaser may make a product
shall prevail.
analysis on products made to this specification in accordance
with Specification A960/A960M.
5. Materials and Manufacture
6.3 The steel shall not contain any unspecified elements for
5.1 The steel shall be killed and shall be melted to a fine
the ordered grade to the extent that it conforms to the
austenitic grain size practice.
requirements of another grade for which that element is a
5.2 Thestartingmaterialshallbewroughtandintheformof
specified element having a required minimum content.
blooms, billets, slabs, forgings, bars, plates, sheets, seamless
pipe or tube, or welded-with-filler-metal pipe or tube. Cast
7. Mechanical Requirements
products shall not be used.
7.1 Tensile Requirements:
5.3 Any forming process, fusion-welding process, or com-
7.1.1 The fittings, as represented by tensile test specimens
bination of such processes, may be used. taken subsequent to final heat treatment, shall conform to the
5.3.1 Allweldingshallbefusion-weldedinaccordancewith
requirements for the applicable grade as specified in Table 2.
the requirements of Section IX of the ASME Boiler and 7.1.2 Number and Location of Specimens:
Pressure Vessel Code. Welding procedures, welders, and weld-
7.1.2.1 Lot—For tension testing, a lot shall consist of the
ing operators shall be qualified in accordance with Section IX fittings from a heat, in each heat treatment charge, with
of the ASME Boiler and Pressure Vessel Code.
nominal wall thicknesses within ⁄4 in. [6 mm] of the nominal
5.3.2 All welded joints shall be finished in accordance with thickness of the test specimen. In addition, for Types 32, 42,
Paragraph UW-35 of Section VIII, Division 1, of the ASME and 52, the lot definition shall include each heat or lot of weld
Code.
metal. If heat treatment is performed in a continuous or
5.3.3 Welded joints of Type 32, 42, and 52 shall be ground batch-type furnace controlled within a range of plus-or-minus
flush.
25 °F [14 °C] and equipped with calibrated thermocouples and
5.3.4 Welded joints ofTypes 31, 41, 51, 32, 42, and 52 shall recording pyrometers, and records of heat treatment are
be examined by radiography in accordance with the require-
maintained, all fittings heat treated in such a furnace are
ments of Paragraph UW-51 of Section VIII, Division 1, of the
ASME Code, and shall conform to the requirements of
Paragraph UW-51.
TABLE 1 Chemical Requirements
Element Cast or Heat
5.4 Heat Treatment—All fittings shall be heat treated sub-
Analysis
sequent to final welding and forming.
5.4.1 Types 30, 31, and 32 fittings shall be normalized by
Carbon, max, % 0.27
uniformly heating to a temperature in the austenitizing range,
Manganese, % 0.85–1.20
Phosphorus, max, % 0.035
but not to exceed 1700 °F [925 °C], and subsequently removed
Sulfur, max, % 0.035
from the furnace and air-cooled individually to room tempera-
Silicon, % 0.15–0.30
ture.
Vanadium, max, % 0.05
A,B
Residual elements
5.4.2 Types 40, 41, and 42 fittings shall be normalized in
Chromium, max, % 0.25
accordance with 5.4.1. After normalizing, the fittings shall be
Nickel, max, % 0.25
temperedbyheatingtoatemperatureintherangefrom1100°F
Molybdenum, max, % 0.08
Copper, max, % 0.35
to 1200 °F [595 °C to 675 °C], soaking at that temperature for
Lead, max, % 0.05
⁄2 h minimum per 1 in. [25 mm] of thickness, but not less than
A
Individual limits of chromium, nickel, molybdenum, and copper may be exceeded
15 min, and then air-cooled to room temperature.
by 0.05 % provided that their total does not exceed 0.90 % in both the heat and
product analysis.
B
These are not to be added to the melt and shall only occur as a result of
AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
unavoidable residuals from the melting stock.
28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
A758/A758M−14 (2019)
TABLE 2 Tensile Requirements
quent to final heat treatment, in accordance with Section IX of
Grade 60 Grade 70 the ASME Boiler and Pressure Vessel Code.
7.2.3 Requirement—The guided-bend test specimen shall
Tensile strength, ksi [MPa] 60 to 85 [415 to 585] 70 to 95 [485 to 635] 1
not have any cracks or other open defects exceeding ⁄8 in. [3
A
Yield strength, min, ksi 35 [240] 38 [260]
mm], measured in any direction on the convex surface of the
[MPa]
Elongation in 2 in. [50 mm],
specimen after bending. Cracks occurring on the corners of the
min, %
specimen during testing shall not be considered unless there is
Longitudinal 30 27
definite evidence that they result from slag inclusions or other
Transverse 22 20
A internal defects.
0.2 % offset or 0.5 % EUL.
8. Dimensions
8.1 Butt-welded fittings shall conform to the dimensions
considered to be in one charge. For furnaces not so equipped
and tolerances specified in ASME B16.9.
and controlled, each batch constitutes a charge.
7.1.2.2 Representative Test Piece—For instances in which
9. Surface Finish, Appearance, and Corrosion Protection
the tension test specimen cannot be obtained from a fitting due
to size limitations, a representative test piece may be used.The
9.1 The requirements of Specification A960/A960M apply.
test piece shall be from the same heat and shall be heat treated
in the same h
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