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: F959/F959M − 17a

Standard Specification for

Compressible-Washer-Type Direct Tension Indicators for
Use with Structural Fasteners, Inch and Metric Series1
This standard is issued under the fixed designation F959/F959M; 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* 1.6 The values stated in either SI units or inch-pound units

1.1 This specification covers the requirements for are to be regarded separately as standard. The values stated in
compressible-washer-type direct tension indicators, (DTIs) each system may not be exact equivalents; therefore, each
capable of indicating the achievement of a specified minimum system shall be used independently of the other. Combining
tension in a structural bolting assembly. values from the two systems may result in non-conformance
with the standard.
1.2 Eight types of DTIs in nominal diameter sizes 1⁄2 1.7 The following precautionary statement pertains only to
through 1 1⁄2 in. as well as M16 through M36 are covered: the test method portions, Section 10 and Appendix X1 of this
1.2.1 Type 325-1—DTIs for use with Specification F3125 specification: This standard does not purport to address all of
Grade A325 Type 1 bolts or Grade F1852 assemblies. the safety concerns, if any, associated with its use. It is the
1.2.2 Type 325–3—DTIs for use with Specification F3125 responsibility of the user of this standard to establish appro-
Grade A325 Type 3 bolts or Grade F1852 Type 3 assemblies. priate safety, health, and environmental practices and deter-
1.2.3 Type 490–1—DTIs for use with Specification F3125 mine the applicability of regulatory limitations prior to use.
Grade A490 Type 1 bolts or Grade F2280 assemblies. 1.8 This international standard was developed in accor-
1.2.4 Type 490–3—DTIs for use with Specification F3125 dance with internationally recognized principles on standard-
Grade A490 Type 3 bolts Grade F2280 Type 3 assemblies. ization established in the Decision on Principles for the
1.2.5 Type 8.8-1—DTIs for use with Specification F3125 Development of International Standards, Guides and Recom-
Grade A325M Type 1 bolts. mendations issued by the World Trade Organization Technical
1.2.6 Type 8.8-3—DTIs for use with Specification F3125 Barriers to Trade (TBT) Committee.
Grade A325M Type 3 bolts.
2. Referenced Documents
1.2.7 Type 10.9-1—DTIs for use with Specification F3125
Grade A490M Type 1 bolts. 2.1 ASTM Standards:2
1.2.8 Type 10.9-3—DTIs for use with Specification F3125 A325 Specification for Structural Bolts, Steel, Heat Treated,
Grade A490M Type 3 bolts. 120/105 ksi Minimum Tensile Strength (Withdrawn
2016)3
1.3 DTIs are intended for installation with the protrusions A325M Specification for Structural Bolts, Steel, Heat
against a hardened surface such as a bolt head, a hardened nut, Treated 830 MPa Minimum Tensile Strength (Metric)
or a hardened washer. (See Research Council on Structural (Withdrawn 2016)3
Connections: Specification for Structural Joints Using High- A490 Specification for Structural Bolts, Alloy Steel, Heat
–Strength Bolts.) Treated, 150 ksi Minimum Tensile Strength (Withdrawn
1.4 This specification provides for furnishing Type 3 DTIs 2016)3
to a Chemical Composition Requirement or a Corrosion A490M Specification for High-Strength Steel Bolts, Classes
10.9 and 10.9.3, for Structural Steel Joints (Metric)
--``,`,,```,,`,`,,`,,,```,,`,-`-`,,`,,`,`,,`---

Resistance Index (CRI) at the manufacturer’s discretion.

(Withdrawn 2016)3
1.5 Terms used in this specification are defined in Termi- A1059 Specification for Zinc Alloy Thermo-Diffusion Coat-
nology F1789 unless otherwise specified. ings (TDC) on Steel Fasteners, Hardware, and Other
Products

1 2
This specification is under the jurisdiction of ASTM Committee F16 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Fasteners and is the direct responsibility of Subcommittee F16.02 on Steel Bolts, contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Nuts, Rivets and Washers. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 1, 2017. Published February 2018. Originally the ASTM website.
3
approved in 1985. Last previous edition approved in 2017 as F959 – 17. DOI: The last approved version of this historical standard is referenced on
10.1520/F0959-17A. www.astm.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

Copyright ASTM International

Provided by IHS Markit under license with ASTM
1Licensee=Army US Army Eng & Support/7838506154, User=Kirby, Daniel
No reproduction or networking permitted without license from IHS Not for Resale, 03/11/2020 06:13:32 MDT
 F959/F959M − 17a
B695 Specification for Coatings of Zinc Mechanically De- 3.1.4 ASTM designation and year of issue (if not specified,
posited on Iron and Steel current issue shall be used);
F436/F436M Specification for Hardened Steel Washers Inch 3.1.5 Type required, 325-1, 325-3, 490-1, 490-3, 8.8-1,
and Metric Dimensions 8.8-3, 10.9-1, 10.9-3 (see 1.2);
F606/F606M Test Methods for Determining the Mechanical 3.1.6 Coating type, if required (4.4);
Properties of Externally and Internally Threaded 3.1.7 Source inspection, if required (Section 11);
Fasteners, Washers, Direct Tension Indicators, and Rivets 3.1.8 Test reports, if required (Section 13); and
F1470 Practice for Fastener Sampling for Specified Me- 3.1.9 Any special requirements.
chanical Properties and Performance Inspection
4. Materials and Manufacture
F1789 Terminology for F16 Mechanical Fasteners
F1852 Specification for “Twist Off” Type Tension Control 4.1 Steel used in the manufacture of DTIs shall be produced
Structural Bolt/Nut/Washer Assemblies, Steel, Heat by the basic-oxygen or electric-furnace process.
Treated, 120/105 ksi Minimum Tensile Strength (With- 4.2 Design:
drawn 2016)3 4.2.1 DTIs shall have a configuration produced by
F2280 Specification for “Twist Off” Type Tension Control extrusion, punching, pressing, or similar forming, to permit a
Structural Bolt/Nut/Washer Assemblies, Steel, Heat measurable decrease in thickness when placed in compression.
Treated, 150 ksi Minimum Tensile Strength (Withdrawn 4.2.2 The design shall be such that the degree of plastic
2016)3 deformation shall indicate the tension in a tightened structural
F3125 Specification for High Strength Structural Bolts, Steel bolt. Supplementary indications of tension are permissible.
and Alloy Steel, Heat Treated, 120 ksi (830 MPa) and 150
ksi (1040 MPa) Minimum Tensile Strength, Inch and 4.3 Heat Treatment:
Metric Dimensions 4.3.1 The heat treatment of DTIs is optional at the manu-
G101 Guide for Estimating the Atmospheric Corrosion Re- facturer’s discretion, provided the DTIs meet all of the me-
sistance of Low-Alloy Steels chanical and performance requirements.
4.3.2 If heat treatment is performed, the process shall be
2.2 Research Council on Structural Connections:4
through-hardening by heating to a temperature above the upper
Specification for Structural Joints Using High–Strength
transformation temperature, quenching in a liquid medium, and
Bolts
tempering by reheating to not less than 800 °F ⁄427 °C.
2.3 ASME Standard:5
ASME B18.2.6 Fasteners for Use in Structural Applications 4.4 Protective Coatings:
ASME B18.2.6M Fasteners for Use in Structural Applica- 4.4.1 Unless otherwise specified, the DTIs shall be fur-
tions nished “plain” with the “as fabricated” surface finish without
protective coatings.
3. Ordering Information 4.4.2 When “zinc coated” or “galvanized” is specified, the
3.1 Orders for DTIs under this specification shall include DTIs shall be zinc coated by the mechanical deposition process
the following: in accordance with the requirements of Class 55 of Specifica-
3.1.1 Quantity (number of pieces); tion B695, or the DTIs shall be zinc coated by the thermal
3.1.2 Name of product (DTI); diffusion process in accordance with the requirements of Class
3.1.3 Size, that is, nominal diameter; 25 of Specification A1059.
4.4.3 Other coatings are to be used only when approved by
the DTI manufacturer.
4
Available from Research Council on Structural Connections at www.boltcoun-
cil.org. 5. Chemical Composition
5
Available from American Society of Mechanical Engineers (ASME), ASME 5.1 DTIs shall conform to the full Heat Analysis specified in
International Headquarters, Three Park Ave., New York, NY 10016-5990, http://
www.asme.org. Table 1 or the requirements of 5.2.

TABLE 1 Chemical Composition Requirements

Composition, %
--``,`,,```,,`,`,,`,,,```,,`,-`-`,,`,,`,`,,`---

Element Heat Product

Analysis Analysis
Type 1 Series Type 3 SeriesA Type 1 Series Type 3 SeriesA
Carbon 0.30–0.55 ... 0.27–0.58 ...
Manganese 0.50–0.90 ... 0.47–0.93 ...
Phosphorus, Max 0.04 0.040 0.048 0.045
Sulfur, Max 0.05 0.050 0.053 0.055
Silicon ... 0.15–0.35 ... 0.13–0.37
Chromium ... 0.45–0.65 ... 0.42–0.68
Nickel ... 0.25–0.45 ... 0.22–0.48
Copper ... 0.25–0.45 ... 0.22–0.48
A
Type 3 DTIs are also permitted to be manufactured from any of the Type 3 steels in the chemical composition sections of Specification F3125. Unless otherwise specified,
the manufacturer may use Type 3 steel to produce Type 1 product.

Copyright ASTM International

Provided by IHS Markit under license with ASTM
2Licensee=Army US Army Eng & Support/7838506154, User=Kirby, Daniel
No reproduction or networking permitted without license from IHS Not for Resale, 03/11/2020 06:13:32 MDT
 F959/F959M − 17a
5.1.1 For all types furnished to the chemical compositions 7.1.1 At the manufacture’s discretion, the number of pro-
in Table 1, Product Analysis may be made by the purchaser trusions may be altered provided there are no fewer than four
from finished DTIs representing each lot. The chemical com- protrusions and the performance requirements of Section 6 are
position shall conform to the requirements given in Table 1, maintained.
Product Analysis. 7.1.2 The minimum outside diameter of the DTIs may
5.2 Type 3 products having Copper, Phosphorus, and Sulfur alternatively match the minimum outside diameter require-
conforming to Table 1 and a Corrosion Resistance Index of 6 ments of the matching nominal size ASTM F436/F436M
or higher calculated on the basis of the Heat Analysis as washer.
described in Guide G101 shall be considered acceptable. See 8. Workmanship, Finish, and Appearance
Note 1.
8.1 The DTIs shall be commercially smooth and free of
NOTE 1—The user is cautioned that the Guide G101 predictive equation injurious material or manufacturing defects that would affect
for calculation of an atmospheric corrosion index has been verified only their performance.
for the composition limits stated in that guide.
5.2.1 Product Analyses are not applicable to Type 3 indica- 9. Number of Tests and Retests
tors furnished to a CRI of 6 or higher. Acceptance shall be 9.1 Responsibility:
based on the CRI of 6 or higher calculated from the Heat 9.1.1 The DTI manufacturer shall inspect each lot of DTIs
Analysis. Other specified Type 3 Steels with Copper, prior to shipment in accordance with the quality assurance
Phosphorus, and Sulfur conforming to the specified limits and procedures described in 9.2.
a Corrosion Resistance of 6 or higher, are acceptable in lieu of 9.1.2 The purchaser is required to maintain the identifica-
compliance with the full specified Chemical Compositions. tion and integrity of each lot following delivery until the
product is installed in its service application.
6. Performance Requirements
9.2 Production Lot Method:
6.1 Compression Loads—When the gap of inch series DTIs 9.2.1 All DTIs shall be processed in accordance with a lot
are compressed to 0.015 in. or metric series DTIs to 0.4 mm, identification control–quality assurance plan. The manufac-
the compression load shall conform to the requirements speci- turer shall identify and maintain the integrity of each produc-
fied in Table 2. tion lot of DTIs from raw material selection through all
6.2 Hardness—When DTIs are heat-treated in accordance processing operations and treatments to final packing and
with 4.3.2, the maximum hardness shall be HRC37. shipment. Each lot shall be assigned its own lot-identification
number, each lot shall be tested, and the inspection test reports

--``,`,,```,,`,`,,`,,,```,,`,-`-`,,`,,`,`,,`---
7. Dimensions for each lot shall be retained.
9.2.2 The minimum number of samples to be tested to
7.1 Except as permitted by 7.1.1 and 7.1.2 the DTIs shall
determine compression loads and coating thickness (when
conform to the dimensional and related requirements of
applicable) shall be in accordance with the requirements
ASME B18.2.6 for inch series and ASME B18.2.6M for metric
specified in Guide F1470.
series products.
9.3 Number of Tests After Alterations—If DTIs are heat
treated, coated, or otherwise altered by a subcontractor or
manufacturer subsequent to testing, they shall be tested in
TABLE 2 Acceptable Range of Compression Loads accordance with 9.2 prior to shipment to the purchaser after all
Compression Load Range in Thousands alterations have been completed.
DTI Size (Nominal Diameter, of Pounds, (kips)
in.) Types 325 and Types 490 and 9.4 When Type 3 products are furnished to a Corrosion
325-3 490-3 Resistance Index, the CRI number shall be calculated for each
⁄
12 12–14 15–18 lot.
⁄
58 19–23 24–29
3⁄4 28–34 35–42 10. Test Methods
7⁄8 39–47 49–59
1 51–61 64–77 10.1 Compression load tests shall be conducted in accor-
1 1⁄ 8 64–77 80–96 dance with Test Methods F606/F606M.
1 1⁄ 4 81–98 102–122
1 3⁄ 8 97–117 121–145
10.1.1 All test specimens shall conform to the values given
1 1⁄ 2 118–143 148–178 in Table 2, regardless of surface coating (lubricants included).
Compression Load Range for Metric
DTI Size (Nominal Diameter, Series in Kilonewtons, (kN) 10.2 DTIs for tests shall be tested full size “as received”
mm) Types 8.8-1 and Types 10.9-1 and without any special preparation.
8.8-3 10.9-3
M16 91–109 114–131 10.3 Results from routine hardness tests performed during
M20 142–170 179–206 production of heat-treated DTIs satisfy the requirement for
M22 176–211 221–254
M24 205–246 257–296
verification that product hardness does not exceed HRC37.
M27 267–320 334–384 10.4 The Corrosion Resistance Index shall be calculated for
M30 326–391 408–469
M36 475–570 595–684 the Heat Analysis in accordance with Guide G101 Predictive
Method based on the data of Larabee and Coburn.

Copyright ASTM International

Provided by IHS Markit under license with ASTM
3Licensee=Army US Army Eng & Support/7838506154, User=Kirby, Daniel
No reproduction or networking permitted without license from IHS Not for Resale, 03/11/2020 06:13:32 MDT
 F959/F959M − 17a
11. Inspection 15. Product Marking
11.1 If the inspection described in 11.2 is required by the 15.1 Each DTI shall be marked to identify the lot number,
purchaser, it shall be specified in the inquiry and contract or manufacturer or private label distributor, as appropriate, and
order. type (see 1.2). Additional markings, at the option of the
11.2 The purchaser’s quality assurance representative shall manufacturer, are permissible.
have free entry to all parts of the manufacturer’s works that 15.2 All markings shall be depressed on the same face of the
concern the manufacture of the DTIs ordered. The manufac- DTI as the protrusions. Raised markings are prohibited.
turer shall afford the quality assurance representative all
reasonable facilities to satisfy him that the DTIs are being 15.3 All DTIs shall have circumferential indentations, or
furnished in accordance with this specification. All tests and other markings, that correspond to and are in alignment with
inspections required by this specification that are requested by feeler gage entry spaces to indicate where feeler gages are to be
the purchaser’s representative shall be made before shipment inserted. Such indentations or markings shall be equally spaced
and shall be conducted so as not to interfere unnecessarily with around the DTI and shall be clearly visible but no so large as
the operation of the plant. to interfere with the function of the DTI.
12. Rejection
16. Packaging and Package Marking
12.1 DTIs that fail to conform to the requirements of this
specification shall be rejected. Rejection should be reported to 16.1 Packaging:
the producer or supplier promptly and in writing. In case of 16.1.1 Unless otherwise specified on the inquiry and order,
dissatisfaction with the results of the test, the producer or packaging shall be in accordance with the supplier’s normal
supplier may make claim for a rehearing. practice.
13. Test Reports 16.2 Package Marking:
13.1 When specified on the order, the manufacturer shall 16.2.1 Each shipping unit shall include or be marked plainly
furnish a test report as described in 13.2. with the following information:
ASTM designation and type,
13.2 The manufacturers shall furnish a test report for each Size,
production lot from which DTIs are supplied to fill a shipment. Name and brand or trademark of the manufacturer or
The report shall show the heat number (to ensure that the private label distributor,
chemical composition is on record and could be furnished upon Number of pieces,
request), compression test loads, a statement indicating that Name of product,
product hardness is less than HRC38, Corrosion Resistance Lot identification number,
Index Number when applicable, measured thickness of protec- Finish, and
tive coatings, gap, nominal size, production lot identification Country of origin.
number, ASTM designation, type and issue date, and purchase
order number. 17. Storage
13.3 When Type 3 products are furnished to a Corrosion
17.1 The DTIs shall be stored in an environment that
Resistance Index, the CRI number shall be furnished for each
preserves the surface condition supplied by the manufacturer.
lot.
14. Responsibility 18. Keywords
14.1 The party responsible for the DTI shall be the organi- 18.1 compressible-washer-type; direct tension indicators;
zation that supplies the DTI to the purchaser. DTI; indicators

--``,`,,```,,`,`,,`,,,```,,`,-`-`,,`,,`,`,,`---

Copyright ASTM International

Provided by IHS Markit under license with ASTM
4Licensee=Army US Army Eng & Support/7838506154, User=Kirby, Daniel
No reproduction or networking permitted without license from IHS Not for Resale, 03/11/2020 06:13:32 MDT
 F959/F959M − 17a
APPENDIX

(Nonmandatory Information)

X1. FIELD TESTING OF DIRECT TENSION INDICATORS FOR BOLT TENSION

DTIs may be field tested in a bolt tension calibrator with Because bolt tension calibrators are “soft” devices, unlike
bolts, nuts, and flat washers, according to the provisions of the hard steel connections, care should be taken to tension the bolts
Research Council of Structural Connections Specification for with a non-impacting wrench so the tension readings can be
Structural Joints Using High-Strength Bolts to determine a job recorded exactly.
inspection gap. The job inspection gap shall be a gap less than
the measured DTI test gap at 1.05× the minimum required bolt
tension.

SUMMARY OF CHANGES

Committee F16 has identified the location of selected changes to this standard since the last issue (F959–17)
that may impact the use of this standard. (December 1, 2017.)

(1) Revised Table 1 to clarify that C1050 is permissible, and

that Type 3 may be supplied when Type 1 is not required.
(2) Revised Table 2—Increased compression load require-
ments on larger diameter Type 325 DTIs to match revised
matching bolt requirements.

Committee F16 has identified the location of selected changes to this standard since the last issue (F959–15)
that may impact the use of this standard. (April 15, 2017.)

(1) Corrected title and standard number for consistency with a (3) Eliminated Certificates of Compliance.
dual inch/metric standard. (4) Added a maximum hardness.
(2) Updated Scope section to point to F3125.

ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned
in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk
of infringement of such rights, are entirely their own responsibility.
--``,`,,```,,`,`,,`,,,```,,`,-`-`,,`,,`,`,,`---

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and
if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards
and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should
make your views known to the ASTM Committee on Standards, at the address shown below.

This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above
address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website
(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222
Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/

Copyright ASTM International

Provided by IHS Markit under license with ASTM
5Licensee=Army US Army Eng & Support/7838506154, User=Kirby, Daniel
No reproduction or networking permitted without license from IHS Not for Resale, 03/11/2020 06:13:32 MDT