Designation: A 416/A416M – 05

Standard Specification for

Steel Strand, Uncoated Seven-Wire for Prestressed
Concrete1
This standard is issued under the fixed designation A 416/A416M; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.

1. Scope* MIL-STD-129 Marking for Shipment and Storage3

1.1 This specification covers two types and two grades of MIL-STD-163 Steel Mill Products Preparation for Ship-
seven-wire, uncoated steel strand for use in pretensioned and ment and Storage3
post-tensioned prestressed concrete construction. The two 2.3 U.S. Federal Standard:
types of strand are low-relaxation and stress-relieved (normal- Fed. Std. No. 123 Marking for Shipments (Civil Agencies)3
relaxation). Low-relaxation strand shall be regarded as the 3. Terminology
standard type. Stress-relieved (normal-relaxation) strand will
not be furnished unless specifically ordered, or by arrangement 3.1 Definitions of Terms Specific to This Standard:
between purchaser and supplier. Grade 1725 [250] and Grade 3.1.1 strand, n—a group of wires having a center wire
1860 [270] have minimum ultimate strengths of 1725 MPa enclosed tightly by six helically placed outer wires with
[250 ksi] and 1860 MPa [270 ksi], respectively, based on the uniform pitch of not less than 12 and not more than 16 times
nominal area of the strand. the nominal diameter of the strand.
1.2 The values stated in either inch-pound units or SI units 3.2 Discussion—The direction of lay may be either right-
are to be regarded as standard. Within the text, the inch-pound or left-hand, however, strands of different lays should not be
units are shown in brackets. The values stated in each system spliced together.
are not exact equivalents; therefore, each system must be used 4. Ordering Information
independently of the other. Combining values from the two
systems may result in nonconformance with the specification. 4.1 Orders for seven-wire low-relaxation or stress-relieved
1.3 The supplementary requirements in S1 shall be specified (normal-relaxation) strand under this specification should in-
for 15.2-mm (0.6-in.) diameter uncoated seven-wire steel clude the following information:
strand if needed for applications in prestressed ground anchors. 4.1.1 Quantity (meters [feet]),
4.1.2 Diameter of strand,
2. Referenced Documents 4.1.3 Grade of strand,
2.1 ASTM Standards: 2 4.1.4 Type of strand,
A 370 Test Methods and Definitions for Mechanical Testing 4.1.5 Packaging,
of Steel Products 4.1.6 ASTM designation and year of issue, and
A 981 Test Method for Evaluating Bond Strength for 15.2 4.1.7 Special requirements, if any.
mm (0.6 in.) Diameter Prestressing Steel Strand, Grade NOTE 1—A typical ordering description is as follows: 25 600 m [84 000
270, Uncoated, Used in Prestressed Ground Anchors ft], 13 mm [0.5 in.], Grade 1860 [270] low-relaxation strand, in 3600-m
E 328 Test Methods for Stress-Relaxation Tests for Materi- [12 000-ft] reelless packs to ASTM A 416/A 416M– _________.
als and Structures
5. Materials and Manufacture
2.2 U.S. Military Standards:
5.1 Base Metal—The base metal shall be carbon steel of
such quality that when drawn to wire, fabricated into strand,
1
This specification is under the jurisdiction of ASTM Committee A01 on Steel, and then thermally treated, shall have the properties and
Stainless Steel, and Related Alloys and is the direct responsibility of Subcommittee characteristics prescribed in this specification.
A01.05 on Steel Reinforcement.
Current edition approved June 1, 2005. Published July 2005. Originally approved
5.2 Wire—The wire from which the strand is to be fabri-
in 1957. Last previous edition approved in 2002 as A 416 – 02. cated shall be round and have a dry-drawn finish.
2
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 3
Available from Standardization Documents Order Desk, Bldg. 4, Section D,
the ASTM website. 700 Robbins Ave., Philadelphia, PA 19111-5094.

*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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 A 416/A416M – 05
NOTE 2—This product is a composite of seven wires and is produced to breaking strength of the strand after 1000 h tested under the
mechanical properties only. The chemistry of all wires or any individual conditions listed in 6.5.1 through 6.5.7.
wire is not pertinent to this application, and heat identity is not necessarily
6.5.1 If required, relaxation evidence shall be provided from
maintained. It is possible that wire from more than one heat may be used
in the manufacture of a reel or pack. Traceability is based on pack identity the manufacturer’s records of tests on similarly dimensioned
as maintained and reported by the manufacturer. strand of the same grade.
6.5.2 The temperature of the test piece shall be maintained
5.3 Treatment—After stranding, low-relaxation strand shall
at 20 6 2°C [68 6 3.5°F].
be subjected to a continuous thermal-mechanical treatment to
6.5.3 The test piece shall not be subjected to loading prior to
produce the prescribed mechanical properties. For stress-
the relaxation test.
relieved (normal-relaxation) strand, only thermal treatment is
necessary. Temper colors which result from the stress-relieving 6.5.4 The initial load shall be applied uniformly over a
operation are considered normal for the finished appearance of period of not less than 3 min and not more than 5 min, and the
this strand. gage length shall be maintained constant; load relaxation
readings shall commence 1 min after application of the total
load.
6. Mechanical Properties
6.5.5 Over-stressing of the test sample during the loading
6.1 Methods of testing for mechanical properties are de- operation shall not be permitted.
scribed in Annex A7 of Test Methods and Definitions A 370. 6.5.6 The duration of the test shall be 1000 h or a shorter
Low-relaxation strand shall also be tested as prescribed in period of at least 200 h, provided it can be shown by records
Methods E 328. that an extrapolation of the shorter period test results to 1000
6.2 Breaking Strength—The breaking strength of the fin- h will provide similar relaxation values as the full 1000 h test.
ished strand shall conform to the requirements prescribed in 6.5.7 The test gage length shall be at least 60 times the
Table 1. nominal diameter. If this gage length exceeds the capacity of
6.3 Yield Strength—Yield strength in kN [pounds] is mea- the extensometer or testing machine, then it is permitted to
sured at 1 % extension under load. The minimum yield strength substitute a gage length of 40 times the nomimal strand
shall be 90 % for low-relaxation strand and 85 % for stress- diameter.
relieved (normal-relaxation) strand of the breaking strength
listed in Table 1. Initial loads for the test and minimum yield
7. Dimensions and Permissible Variations
strengths are listed in Table 2.
6.3.1 The extension under load shall be measured by an 7.1 The size of the finished strand shall be expressed as the
extensometer calibrated with the smallest division not larger nominal diameter of the strand in millimetres [inches].
than 0.0001 mm/mm [0.0001 in./in.] of gage length. 7.2 The diameter of the center wire of any strand shall be
6.4 Elongation—The total elongation under load shall not larger than the diameter of any outer wire in accordance with
be less than 3.5 % using a gage length of not less than 600 mm Table 3.
[24 in.]. In practice the total elongation value may be deter- 7.3 Permissible Variations in Diameter:
mined by adding to the 1.0 % yield extension the percent 7.3.1 All Grade 1725 [250] strand shall conform to a size
extension or movement between the jaws gripping the strand tolerance of 60.40 mm [60.016 in.] from the nominal diam-
after yield determination. The percent is calculated on the new eter measured across the crowns of the wires.
base length of jaw-to-jaw distance. 7.3.2 All Grade 1860 [270] strand shall conform to a size
6.5 Relaxation Properties—Low-relaxation strand shall tolerance of +0.65, − 0.15 mm [+0.026, −0.006 in.] from the
have relaxation losses of not more than 2.5 % when initially nominal diameter measured across the crowns of the wire.
loaded to 70 % of specified minimum breaking strength or not 7.3.3 Variation in cross-sectional area and in unit stress
more than 3.5 % when loaded to 80 % of specified minimum resulting therefrom shall not be cause for rejection provided

TABLE 1 Breaking Strength Requirements

Strand Designation No. Diameter of Strand, mm Minimum Breaking Steel Area of Strand, Weight of Strand kg/1000
[in.] Strength of Strand, kN [lbf] mm2[in.2] m [lb/1000 ft]
Grade 1725 [250]
6 6.4 [0.250] 40.0 [9 000] 23.2 [0.036] 182 [122]
8 7.9 [0.313] 64.5 [14 500] 37.4 [0.058] 294 [197]
9 9.5 [0.375] 89.0 [20 000] 51.6 [0.080] 405 [272]
11 11.1 [0.438] 120.1 [27 000] 69.7 [0.108] 548 [367]
13 12.7 [0.500] 160.1 [36 000] 92.9 [0.144] 730 [490]
15 15.2 [0.600] 240.2 [54 000] 139.4 [0.216] 1094 [737]
Grade 1860 [270]
9 9.53 [0.375] 102.3 [23 000] 54.8 [0.085] 432 [290]
11 11.11 [0.438] 137.9 [31 000] 74.2 [0.115] 582 [390]
13 12.70 [0.500] 183.7 [41 300] 98.7 [0.153] 775 [520]
13a 13.20 [0.520] 200.2 [45 000] 107.7 [.0167] 844 [568]
15 15.24 [0.600] 260.7 [58 600] 140.0 [0.217] 1102 [740]

2
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 A 416/A416M – 05
TABLE 2 Yield Strength Requirements
Strand Nominal Diameter Initial Load, Minimum Load at 1 % Extension,
Designation of Strand kN [lbf] kN [lbf]
No. mm [in.]
Low-Relaxation Normal-Relaxation
Grade 1725 [250]
6 6.4 [0.250] 4.0 [900] 36.0 [8 100] 34.0 [7 650]
8 7.9 [0.313] 6.5 [1 450] 58.1 [13 050] 54.7 [12 300]
9 9.5 [0.375] 8.9 [2 000] 80.1 [18 000] 75.6 [17 000]
11 11.1 [0.438] 12.0 [2 700] 108.1 [24 300] 102.3 [23 000]
13 12.7 [0.500] 16.0 [3 600] 144.1 [32 400] 136.2 [30 600]
15 15.2 [0.600] 24.0 [5 400] 216.2 [48 600] 204.2 [45 900]
Grade 1860 [270]
9 9.53 [0.375] 10.2 [2 300] 92.1 [20 700] 87.0 [19 550]
11 11.11 [0.438] 13.8 [3 100] 124.1 [27 900] 117.2 [26 350]
13 12.70 [0.500] 18.4 [4 130] 165.3 [37 170] 156.1 [35 100]
13a 13.20 [0.520] 20.0 [4 500] 180.1 [40 500] 170.1 [38 250]
15 15.24 [0.600] 26.1 [5 860] 234.6 [52 740] 221.5 [49 800]

TABLE 3 Diameter Relation Between Center and Outer Wires

Strand Nominal Diameter of Strands, Minimum Difference Between
Designation No. mm [in.] Center Wire Diameter and Diameter
of Any Outer Wire, mm [in.]
Grade 1725 [250]
6 6.4 [0.250] 0.025 [0.001]
8 7.9 [0.313] 0.038 [0.0015]
9 9.5 [0.375] 0.051 [0.002]
11 11.1 [0.438] 0.064 [0.0025]
13 12.7 [0.500] 0.076 [0.003]
15 15.2 [0.600] 0.102 [0.004]
Grade 1860 [270]
9 9.53 [0.375] 0.0508 [0.002]
11 11.11 [0.438] 0.0635 [0.0025]
13 12.70 [0.500] 0.0762 [0.003]
13a 13.20 [0.520] 0.0762 [0.003]
15 15.24 [0.600] 0.1016 [0.004]

that the diameter differences of the individual wires and the controlled cooling. There shall be no welds in the wire after it
diameters of the strand are within the tolerances specified. has been drawn through the first die in the wire drawing except
7.4 Specially dimensioned low relaxation and stress- as provided in 8.1.3.
relieved [normal-relaxation] strands with nominal diameters up 8.1.3 During fabrication of the strand, butt-welded joints are
to 19 mm [0.750 in.] may be employed, providing that the permitted in the individual wires, provided there is not more
breaking strength is defined, and the yield strength, as defined than one such joint in any 45-m [150-ft] section of the
in 6.3, is not less than 90 % and 85 % of the specified minimum completed strand.
breaking strength for low-relaxation and stress-relieved (nor-
mal relaxation) strands, respectively. All other requirements 8.1.4 When specifically ordered as “Weldless,” a product
shall apply. free of welds shall be furnished. When “Weldless” is specified,
the strand is produced as one continuous length with no welds
8. Workmanship, Finish, and Appearance as allowed by 8.1.3.
8.1 Joints: 8.2 The finished strand shall be uniform in diameter and
8.1.1 There shall be no strand joints or strand splices in any shall be free of imperfections not consistent with good com-
length of the completed strand unless specifically permitted by mercial strand practices.
the purchaser. 8.3 When the strand is cut without seizings, the wire shall
8.1.2 During the process of manufacture of individual wires not fly out of position. If any wire flies out of position and can
for stranding, welding is permitted only prior to or at the size be replaced by hand, the strand shall be considered satisfactory.
of the last thermal treatment, for example, patenting or

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 A 416/A416M – 05
8.4 The strand shall not be oiled or greased. Slight rusting, basis of acceptance of the material. The certification shall
provided it is not sufficient to cause pits visible to the unaided include the specification number, year-date of issue, and
eye, shall not be cause for rejection. revision letter, if any.
13.2 The manufacturer shall, when requested in the order,
NOTE 3—Guidance for evaluating the degree of rusting on prestressed
concrete strand is presented in Sason.4 furnish a representative load-elongation curve for each size and
grade of strand shipped.
9. Sampling 13.3 When the modulus of elasticity of a seven-wire strand
9.1 Test specimens cut from either end of the strand package is provided, the cross-sectional area used to compute that
are permitted. Any specimen found to contain a wire joint shall modulus also shall be provided. The area provided in the
be discarded and a new specimen obtained. certification shall be the area used to calculate the modulus of
elasticity.
10. Number of Tests 13.4 A material test report, certificate of inspection, or
10.1 One specimen for test shall be taken from each 18-Mg similar document printed from or used in electronic form from
[20-ton] production lot of finished strand, and tested for an electronic data interchange (EDI) transmission shall be
breaking strength, yield strength, and elongation. regarded as having the same validity as a counterpart printed in
the certifier’s facility. The content of the EDI transmitted
11. Inspection document must meet the requirements of the invoked ASTM
11.1 If outside inspection is required, the manufacturer shall standard(s) and conform to any existing EDI agreement be-
afford the inspector representing the purchaser all reasonable tween the purchaser and the supplier. Notwithstanding the
facilities to satisfy that the material is being furnished in absence of a signature, the organization submitting the EDI
accordance with this specification. All tests and inspections transmission is responsible for the content of the report.
shall be made at the place of manufacture prior to shipment, NOTE 5—The industry definition as invoked here is: EDI is the
unless otherwise agreed upon at the time of purchase, and shall computer-to-computer exchange of business information in a standard
be so conducted as not to interfere unnecessarily with the format such as ANSI ASC X12.
operation of the works.
14. Packaging and Marking
NOTE 4—The purchaser should state, at the time of order, whether
outside inspection is required or waived. 14.1 The strand shall be furnished on reels or in reelless
packs having a minimum core diameter of 610 mm [24 in.],
12. Rejection unless otherwise specified by the purchaser. Lengths on reels or
12.1 Failure of any test specimen to comply with the in reelless packs shall be as agreed upon at the time of
requirements of the specification shall constitute grounds for purchase. The strand shall be well protected against mechani-
rejection of the lot represented by the specimen. cal injury in shipping as agreed upon at the time of purchase.
12.2 The lot may be resubmitted for inspection by testing a Each reel or reelless pack shall have two strong tags securely
sample from each reel or pack and sorting out non-conforming fastened to it showing the length, size, type, grade, ASTM
material. designation A 416/A 416M, and the name or mark of the
12.3 In case there is a reasonable doubt in the initial testing manufacturer. One tag shall be positioned where it will not be
as to the ability of the strand to meet any requirement of this inadvertently lost during transit, such as the core of a reelless
specification, two additional tests shall be made on a sample of pack. The other tag shall be placed on the outside for easy
strand from the same reel or pack, and if failure occurs in either identification.
of these tests, the strand shall be rejected. 14.2 For Government Procurement Only— When specified
in the contract or order, and for direct procurement by or direct
13. Certification shipment to the U.S. government, material shall be preserved,
13.1 If outside inspection is waived, a manufacturer’s cer- packaged, and packed in accordance with the requirements of
tification that the material has been tested in accordance with MIL-STD-163. The applicable levels shall be as specified in
and meets the requirements of this specification shall be the the contract. Marking for shipment of such material shall be in
accordance with Fed. Std. No. 123 for civil agencies and
MIL-STD-129 for military agencies.
4
Sason, A.S., “Evaluation of Degree of Rusting on Prestressed Concrete
Strand,’’ PCI Journal, Precast/Prestressed Concrete Institute, Vol. 37, No. 3, 15. Keywords
May-June 1992, pp 25–30. Reprints of this paper are available from the Precast/
Prestressed Concrete Institute, 175 West Jackson Blvd., Suite 1859, Chicago, IL 15.1 prestressed concrete; seven-wire strand (tendon); steel
60604. wire

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 A 416/A416M – 05
SUPPLEMENTARY REQUIREMENTS

Supplementary requirements shall apply only to 15.2-mm (0.6-in.) strand, Grade 270 used in
prestressed ground anchors or similar applications and shall be specified at the time of order
placement. These requirements are not applicable to strand used in prestressed concrete applications.

S1. Bond Capacity without changes in the manufacturing method and materials
S1.1 The results of bond-capacity tests performed in accor- used, three tests shall be considered as adequate.
dance with Specification A 981 shall be submitted to the S1.3 Retests —If the test specimens fail to satisfy S1.2, six
purchaser. The strand samples, on which tests were performed, additional tests shall be performed, and the results shall satisfy
shall be from different lots and shall be representative for the the acceptance criteria. Strand that failed the retest shall not be
strand ordered. considered acceptable for the use in prestressed ground an-
S1.2 The average pull force from six pull tests, performed in chors.
accordance with Specification A 981, required to reach the S1.4 Annual Tests—The pull tests shall be performed annu-
0.25-mm (0.01-in.) displacement described therein shall be at ally as a minimum or repeated when, in the opinion of the
least 35.6 kN (8000 lbf), with the individual minimum test producer, a process change is made which is believed could
value not less than 30.2 kN (6800 lbf). For any future retests, decrease the bond capacity of the strand.

SUMMARY OF CHANGES

Committee A01 has identified the location of the following changes to this standard since the last issue (A
416/A 416M–02) that may impact the use of this standard.

(1) Revised Table 1, Table 2, and Table 3 to include Strand

Designation No. 13a.

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