ASTM F2329/F2329M-15(2023)
(Specification)Standard Specification for Zinc Coating, Hot-Dip, Requirements for Application to Carbon and Alloy Steel Bolts, Screws, Washers, Nuts, and Special Threaded Fasteners
Standard Specification for Zinc Coating, Hot-Dip, Requirements for Application to Carbon and Alloy Steel Bolts, Screws, Washers, Nuts, and Special Threaded Fasteners
ABSTRACT
This specification covers the requirements for hot-dip zinc coating applied to carbon steel and alloy steel bolts, screws, washers, nuts, and special threaded fasteners applied by the hot-dip coating process. The zinc used for the coating shall conform to the chemical composition required. The following tests shall be made to ensure that the zinc coating is being furnished in accordance with this specification: coating thickness; finish and appearance; embrittlement test; and adhesion test.
SCOPE
1.1 This specification covers the requirements for hot-dip zinc coating applied to carbon steel and alloy steel bolts, screws, washers, nuts, and special threaded fasteners. It also provides for minor coating repairs. Nails and rivets are not included in this specification.
1.2 It is intended to be applicable to fasteners that are centrifuged or otherwise handled to remove excess galvanizing bath metal (free zinc).
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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 standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
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.
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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: F2329/F2329M − 15 (Reapproved 2023)
Standard Specification for
Zinc Coating, Hot-Dip, Requirements for Application to
Carbon and Alloy Steel Bolts, Screws, Washers, Nuts, and
Special Threaded Fasteners
This standard is issued under the fixed designation F2329/F2329M; 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* Iron and Steel Hardware
A394 Specification for Steel Transmission Tower Bolts,
1.1 This specification covers the requirements for hot-dip
Zinc-Coated and Bare
zinc coating applied to carbon steel and alloy steel bolts,
A563 Specification for Carbon and Alloy Steel Nuts (Metric)
screws, washers, nuts, and special threaded fasteners. It also
A0563_A0563M
provides for minor coating repairs. Nails and rivets are not
A563M Specification for Carbon and Alloy Steel Nuts (Met-
included in this specification.
ric) (Withdrawn 2021)
1.2 It is intended to be applicable to fasteners that are
A780/A780M Practice for Repair of Damaged and Uncoated
centrifuged or otherwise handled to remove excess galvanizing
Areas of Hot-Dip Galvanized Coatings
bath metal (free zinc).
B487 Test Method for Measurement of Metal and Oxide
1.3 The values stated in either SI units or inch-pound units Coating Thickness by Microscopical Examination of
Cross Section
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each E376 Practice for Measuring Coating Thickness by
Magnetic-Field or Eddy Current (Electromagnetic) Test-
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance ing Methods
F606/F606M Test Methods for Determining the Mechanical
with the standard.
Properties of Externally and Internally Threaded
1.4 This standard does not purport to address all of the
Fasteners, Washers, Direct Tension Indicators, and Rivets
safety concerns, if any, associated with its use. It is the
F1470 Practice for Fastener Sampling for Specified Me-
responsibility of the user of this standard to establish appro-
chanical Properties and Performance Inspection
priate safety, health, and environmental practices and deter-
F1789 Terminology for F16 Mechanical Fasteners
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
3. Terminology
dance with internationally recognized principles on standard-
3.1 Definitions:
ization established in the Decision on Principles for the
3.1.1 Terms used in this specification are defined in Termi-
Development of International Standards, Guides and Recom-
nology F1789 unless otherwise defined in this specification.
mendations issued by the World Trade Organization Technical
3.1.2 batch lot—quantity of identical parts cleaned, pickled,
Barriers to Trade (TBT) Committee.
fluxed, and galvanized together at one time in a galvanizing
basket.
2. Referenced Documents
3.1.3 galvanizing—hot-dip zinc coating.
2.1 ASTM Standards:
A153/A153M Specification for Zinc Coating (Hot-Dip) on
3.1.4 high temperature galvanizing—galvanizing process
carried out in a ceramic vessel (kettle) at an approximate
temperature ranging between 990 °F and 1040 °F [530 °C and
This specification is under the jurisdiction of ASTM Committee F16 on
560 °C].
Fasteners and is the direct responsibility of Subcommittee F16.03 on Coatings on
3.1.5 hot-dip zinc coating of mechanical fasteners—process
Fasteners.
Current edition approved Nov. 1, 2023. Published November 2023. Originally
whereby fasteners are zinc coated by immersion in a bath of
approved in 2005. Last previous edition approved in 2015 as F2329 – 15. DOI:
molten zinc, resulting in the formation of the iron/zinc alloy
10.1520/F2329_F2329-15R23.
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 last approved version of this historical standard is referenced on
the ASTM website. 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
F2329/F2329M − 15 (2023)
A
TABLE 1 Process Control of Batch Lot
coating and a zinc coating at the surface of the fastener. This
Sampling Plan
process involves the removal of excess zinc by spinning the
B
Sample Size
parts in a centrifuge, or brushing the threaded portion, or
D
handling otherwise to remove the excess zinc. Batch Lot Size Average Coating Adhesion Appearance
C
Thickness
3.1.6 production lot—batches of parts originating from the
5 to 25 1 1 1
same manufacturing lot, processed continuously through
26 to 50 1 1 2
cleaning, pickling, fluxing, dipping in molten zinc and spun in
51 to 150 2 1 2
151 and over 2 2 2
a centrifuge, or other means, without any significant change in
A
The acceptance criterion in all cases is zero defects.
time, temperature, and concentration of the constituents of the
B
The sample size is the number of specimen(s) required to be tested/inspected to
process.
the applicable criteria.
C
Frequency of coating thickness measurements: one set of specimen(s) for every
3.1.7 stress relief—process of heating parts for a definite
five batch lots. For test method, see 11.1.
time at a given temperature in order to relieve stress induced by
D
Visual inspection for conformance.
work hardening.
4. Ordering Information
finishing-tool operation) by the galvanizer unless specifically
4.1 Orders for zinc coating of fasteners to this specification
authorized in writing by the purchaser.
shall include the following:
5.4.2 Hot-dip galvanizing of externally threaded fasteners
4.1.1 Name of product (that is bolt, stud, nut, washers, or
shall meet the thread fitting requirements of the specified
other);
product standard or specific allowance as determined by the
4.1.2 ASTM designation and year of issue, including fas-
customer.
tener specification number;
NOTE 1—The scope of this specification does not cover the require-
4.1.3 Hydrogen embrittlement relief treatment, as required
ments regarding the overtapping of galvanized nuts. These requirements
by the purchaser (see, 7.2.3);
are established by the applicable product standard, such as Specification
4.1.4 Quantity of fasteners to be hot-dip zinc coated;
A563, Specification A563M (or others), or in writing by the purchaser, if
4.1.5 Stress relief or tempering temperature to which the needed.
fasteners where subjected, if applicable;
5.5 Secondary Processing:
4.1.6 Secondary processing such as chromating,
5.5.1 When requested by the purchaser, treatments such as
phosphating, or lubrication, if applicable;
chromating or phosphating shall be applied to reduce the
4.1.7 Average galvanizing temperature to which fasteners
possibility of wet storage staining (white corrosion) or to assist
will be subjected, if required by the purchaser (see 7.2.2);
subsequent painting.
4.1.8 Specify baking if required (see 7.2.3); and
5.5.2 When specified on the purchase order, the nuts, bolts,
4.1.9 Certification, if required (see 14.1).
or screws shall be lubricated to enhance assembly.
4.1.10 Supplementary Requirements (See S1).
5.6 Touch-up and Repair—Bare, cut, or damaged spots
found on fasteners after galvanizing, totaling less than 1 % of
5. Materials and Manufacture
the coated surface area, may be repaired with paints containing
5.1 Condition of the As-Received Fasteners—The fasteners
zinc dust. Such paints shall have zinc-dust concentrations of 65
as received by the galvanizer shall be free from contaminants
to 69 % or concentrations above 92 % in the dried film. The
that are not readily removed in the cleaning process and would
repairing party shall select the paint and follow its application
adversely affect the galvanizing.
instructions. The applied coating shall provide barrier
5.2 Process—Unless otherwise covered in this specification,
protection, and preferably be anodic to steel. Thickness mea-
all processing parameters shall be in accordance with the
surements of repaired areas shall not be required.
requirements of Specification A153/A153M.
NOTE 2—Experience shows that, in general, organic zinc-rich systems
5.2.1 Process Control—Galvanized fasteners subjected to a
are tolerant of marginal surface preparation and are not critical of
process control plan based upon batch lot level shall comply
climactic or atmospheric conditions for curing. Corrosion resistance and
with the batch lot sampling plan in Table 1, and the sampling service performance are very dependent on the properties of the paint
system, the extent of surface preparation, and the skills of individual
plan for production lot (prevention process) as determined in
applicators. See Practice A780/A780M.
10.2.2 shall be applied.
6. Chemical Composition of Zinc
5.3 Spinning and Quenching:
5.3.1 Parts shall be spun immediately following removal
6.1 Unless otherwise specified in the product standard, the
from the galvanizing bath and quenched in water. In addition,
zinc used for the coating shall conform to the requirements of
small parts shall be air cooled, as needed, in order to prevent
the section on Zinc of Specification A153/A153M.
the formation of zinc oxide.
5.3.2 Parts, which cannot be spun shall be brushed or 7. Safeguards Against Alteration of Fasteners Mechanical
handled otherwise to remove the excess zinc. Properties
5.4 Alteration of Threaded Fasteners: 7.1 Stress Relief—Fasteners subjected to severe work hard-
5.4.1 Fasteners that have been hot-dip galvanized shall not ening shall be stress-relieved by the fastener manufacturer
be further altered (such as subjected to a cutting, rolling, or prior to hot-dip zinc coating (galvanizing).
F2329/F2329M − 15 (2023)
7.2 Hot-Dip Zinc Coating: ment S1 when specifying coating thickness for fasteners
7.2.1 Effect of Temperature on Mechanical Properties: meeting the requirements of Specification A394.
7.2.1.1 Galvanizing carried out at a temperature above
8.2 Dimension—The dimensional characteristics of the fas-
800 °F [425 °C] can adversely affect the final mechanical
teners shall be in accordance with the requirements of the
properties of the fasteners. Therefore, the supplier of the
purchaser, when specified in the order. The purchaser shall
fasteners submitting the product to the galvanizer shall be
ensure that the effect of the heat generated by the galvanizing
aware of the tempering temperature of the fasteners relative to
process is compatible with the fastener regarding the final
the temperature of the galvanizing bath and the potential effect
dimensional characteristics of the parts. Furthermore, the
it may have on the product. When requested by the purchaser,
galvanizer shall not be held responsible for any unanticipated
the average galvanizing temperature that the fasteners will be
distortion of parts. In addition, the purchaser shall provide
subjected to shall be furnished.
fasteners having sufficient dimensional allowance to accom-
7.2.1.2 Unless otherwise required by the product standard or
modate the zinc thickness deposition, as required in 8.1.
by the purchaser, testing for mechanical properties is not
necessary if the galvanizing process is carried out at a lower 8.3 Adhesion of Zinc Coating—The zinc coating shall ad-
temperature than the stress relief or tempering temperature of here tenaciously to the surface of the base metal. The method
the fasteners. If the galvanizing process is carried out at a
for testing the condition of adherence is specified in 11.5.
higher temperature than the stress relief or the tempering
temperature of the fasteners, than the purchaser shall make
9. Workmanship, Finish, and Appearance
provision for mechanical testing.
9.1 Appearance of Zinc Coating:
7.2.1.3 Threaded fasteners made from carbon or alloy steel
9.1.1 After hot-dip galvanizing, the fasteners shall meet the
heat treated to a minimum specified hardness of 40 HRC, or
requirements of the section on Workmanship, Finish, and
case hardened steel fasteners shall not be hot-dip zinc coated.
Appearance of Specification A153/A153M. Galvanized wash-
7.2.2 Effect of Hydrogen on the Mechanical Properties after
ers shall not be bonded to each other (See Note 3). Parts may
Galvanizing—Hydrogen has the potential of being introduced
be dull due to the presence of silicon in the steel. The dull
into the steel during acid pickling, prior to hot-dip galvanizing.
appearance shall not be cause for rejection.
For high strength fasteners (having a specified minimum
product hardness of 33 HRC), there is a risk of internal
NOTE 3—Hot-dip washers tend to bond to each other. Suitable accep-
hydrogen embrittlement. If required by the product standard or
tance criteria shall be agreed between the purchaser and the galvanizer
before placing the order. Unless otherwise agreed to in the purchase order,
by the purchaser, mechanical descaling (with or without flash
delivered galvanized washers shall not be bonded to each other.
pickling) or baking shall be conducted to reduce the risk of
internal hydrogen embrittlement. Baking shall be conducted
9.1.2 The test method shall be in accordance with 11.3.
after pickling and prior to hot-dip galvanizing.
9.2 Smoothness of Zinc Coating:
7.2.3 Effect of the Galvanizing Temperature—Externally
9.2.1 The zinc coating shall be smooth and reasonably
threaded ferrous fasteners over 1.00 in. [M24] diameter with a
uniform in thickness, as defined in the section on
specified minimum hardness of HRC 33 and higher shall not be
Workmanship, Finish, and Appearance of Specification A153/
hot-dip zinc coated at high temperature (see definition in 3.1.4)
A153M. Smoothness of a surface is a relative term. Minor
in order to avoid microcracks.
roughness that does not impair the intended use of the part, or
8. Coating and Dimensional Requirements
roughness that is related to the uncoated surface condition of
the part, shall not constitute grounds for rejection of the parts.
8.1 Coating Thickness—The zinc coating thickness shall
meet the requirements of Table 2. See Supplementary Require- 9.2.2 The test method shall be in accordance with 11.3.
TABLE 2 Zinc Coating Thickness
Minimum Thickness on Surface
A,B
Dimension Average Thickness of All Average Thi
...
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