ASTM A556/A556M-18

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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: A556/A556M − 96 (Reapproved 2012) A556/A556M − 18
Standard Specification for
Seamless Cold-Drawn Carbon Steel Feedwater Heater
Tubes
This standard is issued under the fixed designation A556/A556M; 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*
1.1 This specification covers minimum-wall-thickness, seamless cold-drawn carbon steel tubes including bending into the form
of U-tubes, if specified, for use in tubular feedwater heaters.
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1.2 The tubing sizes covered shall be ⁄8 to 1 ⁄4-in. [15.9 to 31.8-mm] outside diameter, inclusive, with minimum wall
thicknesses equal to or greater than 0.045 in. [1.1 mm].
1.3 Optional supplementary requirements are provided, and when desired, shall be stated in the order.
1.4 The values stated in either inch-pound units or SI units are to be regarded separately as the standard. Within the text, the
SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used
independently of the other. Combining values from the two systems may result in nonconformance with the specification. The
inch-pound units shall apply unless the “M” designation of this specification is specified in the order.
1.5 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
2.1 ASTM Standards:
A450/A450M Specification for General Requirements for Carbon and Low Alloy Steel Tubes
E30A751 Test Methods Methods, Practices, and Terminology for Chemical Analysis of Steel, Cast Iron, Open-Hearth Iron, and
Wrought IronSteel Products (Withdrawn 1995)
3. Ordering Information
3.1 Orders for material under this specification should include the following as required to describe the desired material
adequately:
3.1.1 Quantity (feet, metres, or number of pieces),
3.1.2 Name of material (seamless steel tubing),
3.1.3 Dimensions (outside diameter and minimum wall thickness),
3.1.4 Length (specific or random),
3.1.5 Manufacture (cold drawn),
3.1.6 Grade (chemical composition),
3.1.7 Optional requirements,
3.1.8 Bending Requirements—If order specifies tubes to be bent, the design of the U-tubes shall accompany the order. Purchaser
must specify if stress-relief anneal of the U-bends is required,
3.1.9 Test report required (see Certification Section of Specification A450/A450M),
3.1.10 Specification number, and
3.1.11 Special requirements and any supplementary requirements selected.
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.09
on Carbon Steel Tubular Products.
Current edition approved March 1, 2012Sept. 1, 2018. Published November 2012September 2018. Originally approved in 1965. Last previous edition approved in
20052012 as A556/A556M – 96 (2005).(2012). DOI: 10.1520/A0556_A0556M-96R12. 10.1520/A0556_A0556M-18.
For ASME Boiler and Pressure Vessel Code applications see related Specification SA-556 in Section II of that Code.
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.
*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
A556/A556M − 18
4. General Requirements
4.1 Material furnished to this specification shall conform to the applicable requirements of the current edition of the
Specification A450/A450M, unless otherwise provided herein.
5. Manufacture
5.1 Manufacture—Tubes shall be made by the seamless process and shall be cold drawn.
5.2 Heat Treatment:
5.2.1 Cold-drawn tubes shall be heat treated after the final cold-draw pass at a temperature of 1200°F [640°C] or higher to
ensure ductility satisfactory for rolling into tube sheets and to meet mechanical properties as specified.
5.2.2 If stress-relief anneal of the U-bends is specified, the anneal shall consist of heating the bent portion within a range of 1100
to 1200°F [585 to 640°C].
6. Chemical Composition
6.1 The steel shall conform to one of the requirements as to chemical composition as prescribed in Table 1.
6.2 When a grade is ordered under this specification, supplying an alloy grade that specifically requires the addition of any
element other than those listed for the ordered grade in Table 1 is not permitted.
7. Product Analysis
7.1 When requested in the purchase order, a product analysis shall be made by the manufacturer or supplier from one tube or
billet per heat.
7.2 If the original test for product analysis fails, retests of two additional tubes or billets shall be made. Both retests for the
elements in question shall meet the requirements of this specification; otherwise, all remaining material in the heat or lot (Note
1) shall be rejected or, at the option of the producer, each tube may be individually tested for acceptance. Tubes that do not meet
the requirements of this specification shall be rejected.
NOTE 1—For tension and hardness test requirements, the term lot applies to all tubes prior to cutting, of the same nominal diameter and wall thickness
which are produced from the same heat of steel. When final heat treatment is in a batch-type furnace, a lot shall include only those tubes of the same
size and the same heat which are heat treated in the same furnace charge. When the final heat treatment is in a continuous furnace, a lot shall include
all tubes of the same size and heat, heat treated in the same furnace at the same temperature, time at heat and furnace speed.
7.3 For referee purposes, Test Methods E30A751 shall be used.
8. Mechanical Properties
8.1 Tensile Properties—The material shall conform to the requirements as to tensile properties prescribed in Table 2, when
pulled in full section.
8.2 Hardness Requirements—The tubes shall not exceed the Rockwell Hardness shown in Table 3.
9. Permissible Variations in Dimensions (Fig. 1)
9.1 Permissible variations from the specified outside diameter shall not exceed 60.004 in. [0.10 mm] for tubing under 1.0-in.
[25.4-mm] outside diameter nor 60.006 in. [0.15 mm] for tubing 1.0 in. [25.4 mm] to 1.25 in. [31.7 mm] inclusive. These
tolerances do not apply to the bent portion of the U-tubes. At the bent portion of a U-tube for R = 2 × D or greater neither the major
nor minor diameter of tube shall deviate from nominal by more than 10 %. If 1 ⁄2 D is specified, tolerances could be greater.
9.2 Permissible variations from the specified minimum wall thickness shall not exceed +20 % or −0. The wall thickness of the
tube in U-bent section shall be not less than value determined by:
t 5 T 2R / 2R1D (1)
~ ! ~ !
f
where:
t = wall thickness after bending, in. [mm],
f
T = specified minimum tube wall thickness, in. [mm],
TABLE 1 Chemical Requirements
Element Composition, %
Grade A2 Grade B2 Grade C2
Carbon, max 0.18 0.27 0.30
Manganese 0.27–0.63 0.29–0.93 0.29–1.06
Phosphorus, max 0.035 0.035 0.035
Sulfur, max 0.035 0.035 0.035
Silicon, min . 0.10 0.10
A556/A556M − 18
TABLE 2 Tensile Requirements
Grade A2 Grade B2 Grade C2
Tensile strength, min, ksi [MPa] 47 [320] 60 [410] 70 [480]
Yield strength, min, ksi [MPa] 26 [180] 37 [260] 40 [280]
Elongation in 2 in. or 50 mm, 35 30 30
min, % (longitudinal)
TABLE 3 Hardness Requirements
Grade A2 HR B 72
Grade B2 HR B 79
Grade C2 HR B 89
TABLE 3 Hardness Requirements
Grade A2 72 HRBW
Grade B2 79 HRBW
Grade C2 89 HRBW
R = centerline bend radius, in. [mm], and
D = nominal outside tube diameter, in. [mm].
9.3 In the case of U-tubes, the length of the tube legs as measured from the point of tangency of the bend and the tube leg to
the end of the tube leg shall not be less than specified, but may exceed the specified values by the amount given in Table 4. The
difference in lengths of the tube legs shall not be greater than ⁄8 in. [3 mm] unless otherwise specified.
9.4 The end of any tube may depart from square by not more than the amount given in Table 5.
9.5 The leg spacing measured between the points of tangency of the bend to the legs shall not vary from the value (2R −
specified tube OD) by more than ⁄16 in. [1.5 mm] where R is the centerline bend radius.
9.6 The bent portion of the U-tube shall be substantially uniform in curvature and not exceed 6 ⁄16 in. [61.5 mm] of the normal
centerline radius.
10. Workmanship, Finish, and Appearance
10.1 Finished tubes shall be free from scale but may have a superficial oxide film on the surfaces. A light oxide scale on the
outside and inside surfaces of U-bend shall be allowed for tubes which have been heat treated.
10.2 Finished tubes shall be reasonably straight and have smooth ends free from burrs. Tubes shall have a workmanlike finish
and shall be free of surface imperfections that cannot be removed within the allowable wall tolerances. Removal of surface
imperfections such as handling marks, straightening marks, light mandrel and die marks, shallow pits, and scale pattern will not
be required provided they are within the allowable wall tolerances.
10.3 Finished tubes shall be coated both on the outside and the inside diameter to prevent corrosion in transit. The type of
coating applied should be mutually agreed upon and specified in the order.
11. Mechanical Tests Required
11.1 Tension Test—One tension test shall be made on a specimen for lots of not more than 50 tubes. Tension tests shall be made
on specimens from two tubes for lots of more than 50 tubes (Note 1).
11.2 Flattening Test—One flattening test shall be made on specimens taken from each end of one finished tube, not the one used
for the flaring test, from each lot of not more than 125 tubes or fraction thereof.
11.3 Flaring Test—One flaring test shall be made on specimens taken from each end of one finished tube, not the one used for
flattening test, from each lot of not more than 125 tubes or fraction thereof.
11.4 Hardness Test—Brinell or Rockwell hardness tests shall be made on specimens from two tubes from each lot (Note 1).
11.5 Hydrostatic Test—Each U-tube shall be subjected to a hydrostatic test, using a noncorrosive fluid, or when agreed upon
between the purchaser and manufacturer, they may be tested at 1 ⁄2 times the specified design working pressure.
12. Nondestructive Test (Electric Test)
12.1 Each tube shall be tested after the finish heat treatment following the final cold-drawn pass by passing through a
nondestructive tester capable of detecting defects on the entire cross section of the tube, in accordance with Specification
A450/A450M.
A556/A556M − 18
FIG. 1 Bent Portion of U-Tube
TABLE 4 Tube Leg Length Tolerance
Leg Length, ft [m] Plus Tolerance in. [mm]
Up to 20 [6], incl ⁄8 [3.2]
Over 20 to 30 [6 to 9], incl ⁄32 [4.0]
Over 30 to 40 [9 to 12.2], incl ⁄16 [4.8]
TABLE 5 Squareness of Ends Tolerance
Tube OD, in. [mm] Tolerance,
in. [mm]
⁄8 [15.9] 0.010 [0.25]
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Over ⁄8 to 1 ⁄4 [15.9 to 31.7], incl 0.016 [0.4]
13. Packaging and Package Marking
13.1 The tubing shall be packaged or bundled in such
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