ASTM A688/A688M-24

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A688/A688M − 18 (Reapproved 2022) A688/A688M − 24
Standard Specification for
Seamless and Welded Austenitic Stainless Steel Feedwater
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Heater Tubes
This standard is issued under the fixed designation A688/A688M; 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 Scope*
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1.1 This specification covers seamless and welded austenitic stainless steel feedwater heater tubes including those bent, if
specified, into the form of U-tubes for application in tubular feed-water heaters.
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1.2 The tubing sizes covered shall be ⁄8 to 1 in. [15.9 to 25.4 mm] inclusive outside diameter, and average or minimum wall
thicknesses of 0.028 in. [0.7 mm] and heavier.
1.3 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.
1.4 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.
2. Referenced Documents
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2.1 ASTM Standards:
A262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
A480/A480M Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip
A941 Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys
A1016/A1016M Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel
Tubes
E112 Test Methods for Determining Average Grain Size
E527 Practice for Numbering Metals and Alloys in the Unified Numbering System (UNS)
2.2 Other Standard:
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SAE J1086 Practice for Numbering Metals and Alloys (UNS)
3. Terminology
3.1 Definitions Of Terms—For definitions of terms used in this specification, refer to Terminology A941.
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This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.10
on Stainless and Alloy Steel Tubular Products.
Current edition approved Sept. 1, 2022March 1, 2024. Published October 2022April 2024. Originally approved in 1973. Last previous edition approved in 20182022 as
A688/A688M – 18.A688/A688M – 18 (2022). DOI: 10.1520/A0688_A0688M-18R22.10.1520/A0688_A0688M-24.
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For ASME Boiler and Pressure Vessel Code applications see related Specification SA-688 in Section II of that Code.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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Available from Society of Automotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001, http://www.sae.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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A688/A688M − 24
4. Ordering Information
4.1 It is the responsibility of the purchaser to specify all requirements that are necessary for material under this specification. Such
requirements may include, but are not limited to, the following:
4.1.1 Quantity (length or number of pieces),
4.1.2 Material description (seamless or welded),
4.1.3 Dimensions—Outside diameter, wall thickness (minimum or average wall), and length,
4.1.4 Grade (chemical composition) (Table 1),
4.1.5 U-bend requirements, if order specifies bending, U-bend schedules or drawings shall accompany the order,
4.1.6 Optional requirements—Purchaser shall specify if annealing of the U-bends is required or whether tubes are to be
hydrotested or air tested (see 11.8)
4.1.7 Supplementary requirements—Purchaser shall specify on the purchase order if material is to be eddy current tested in
accordance with Supplementary Requirements S1 or S2, and if spe
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