ASTM F2329/F2329M-15(2023)

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.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: F16 - Fasteners
• Drafting Committee: F16.03 - Coatings on Fasteners

Relations

• Replaces: ASTM F2329/F2329M-15 - Standard Specification for Zinc Coating, Hot-Dip, Requirements for Application to Carbon and Alloy Steel Bolts, Screws, Washers, Nuts, and Special Threaded Fasteners
• Effective Date: 01-Nov-2023
• Refers: ASTM F1470-24 - Standard Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
• Effective Date: 01-Jan-2024
• Refers: ASTM A394-08(2024) - Standard Specification for Steel Transmission Tower Bolts, Zinc-Coated and Bare
• Effective Date: 01-Jan-2024
• Refers: ASTM F1789-23 - Standard Terminology for F16 Mechanical Fasteners
• Effective Date: 01-Nov-2023
• Refers: ASTM F1789-22 - Standard Terminology for F16 Mechanical Fasteners
• Effective Date: 01-Nov-2022
• Refers: ASTM F1470-19 - Standard Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
• Effective Date: 01-Aug-2019
• Refers: ASTM A394-08(2015) - Standard Specification for Steel Transmission Tower Bolts, Zinc-Coated and Bare
• Effective Date: 15-Jun-2015
• Referred By: ASTM A194/A194M-23 - Standard Specification for Carbon Steel, Alloy Steel, and Stainless Steel Nuts for Bolts for High Pressure or High Temperature Service, or Both
• Effective Date: 01-Nov-2023
• Referred By: ASTM A193/A193M-23 - Standard Specification for Alloy-Steel and Stainless Steel Bolting for High Temperature or High Pressure Service and Other Special Purpose Applications
• Effective Date: 01-Nov-2023
• Referred By: ASTM A307-21 - Standard Specification for Carbon Steel Bolts, Studs, and Threaded Rod 60 000 PSI Tensile Strength
• Effective Date: 01-Nov-2023
• Referred By: ASTM F1554-20 - Standard Specification for Anchor Bolts, Steel, 36, 55, and 105-ksi Yield Strength
• Effective Date: 01-Nov-2023
• Referred By: ASTM A354-17e2 - Standard Specification for Quenched and Tempered Alloy Steel Bolts, Studs, and Other Externally Threaded Fasteners
• Effective Date: 01-Nov-2023
• Referred By: ASTM A489-18e1 - Standard Specification for Carbon Steel Eyebolts
• Effective Date: 01-Nov-2023
• Referred By: ASTM A563/A563M-21ae1 - Standard Specification for Carbon and Alloy Steel Nuts (Inch and Metric)
• Effective Date: 01-Nov-2023
• Referred By: ASTM F844-19 - Standard Specification for Washers, Steel, Plain (Flat), Unhardened for General Use
• Effective Date: 01-Nov-2023

Overview

ASTM F2329/F2329M-15(2023), titled Standard Specification for Zinc Coating, Hot-Dip, Requirements for Application to Carbon and Alloy Steel Bolts, Screws, Washers, Nuts, and Special Threaded Fasteners, sets forth the minimum requirements for hot-dip zinc coatings applied to carbon steel and alloy steel fasteners using the hot-dip galvanizing process. This international standard ensures that zinc coating processes deliver reliable corrosion protection, proper coating thickness, and maintain the mechanical properties and performance of bolts, screws, washers, nuts, and other special threaded fasteners.

The scope of ASTM F2329/F2329M does not cover nails or rivets and is specifically designed for fasteners that are centrifuged or otherwise handled to remove excess zinc after galvanizing. The standard specifies requirements for surface preparation, zinc composition, coating characteristics, sampling, inspection, and repair methods, facilitating global trade and compliance with WTO Technical Barriers to Trade (TBT) principles.

Key Topics

• Hot-Dip Galvanized Fastener Coatings
  Requirements for the application of zinc coatings to carbon and alloy steel fasteners using a molten zinc bath.

• Coating Thickness and Uniformity
  Minimum coating thickness levels are required for different diameters and types of fasteners, ensuring effective corrosion protection.

• Testing and Inspection
  Includes procedures for coating thickness measurements (microscopical, magnetic, and eddy current), adhesion tests, finish and appearance assessments, and embrittlement evaluations.

• Surface Preparation and Process Control
  Guidelines for cleaning, pickling, and spinning or brushing fasteners to remove excess zinc and achieve a uniform finish.

• Coating Repairs
  Allows minor repairs of bare or damaged areas using paint with specified zinc content per ASTM guidelines.

• Mechanical and Dimensional Integrity
  Safeguards in place to maintain the mechanical properties of fasteners post-galvanizing, including stress relief and temperature control requirements.

Applications

ASTM F2329/F2329M is widely referenced in industries where corrosion resistance and mechanical integrity of steel fasteners are critical, including:

• Structural Steel Construction
  Used for hot-dipped galvanized bolts, screws, washers, and nuts in bridges, buildings, and towers, ensuring long-term durability.

• Utility and Transmission Infrastructure
  Electrical transmission towers, and energy infrastructure often specify fasteners conforming to this standard to prevent corrosion and maintain connections.

• Manufacturing and Machinery
  Ensures that machine bolts, screws, and nuts exposed to outdoor or corrosive environments meet zinc coating quality requirements.

• OEM Parts and Assemblies
  Satisfies procurement requirements for automotive, transportation, and heavy equipment manufacturers sourcing pre-coated fasteners.

By specifying the zinc coating procedures and acceptance criteria, this standard helps manufacturers, specifiers, and purchasers achieve consistent quality in the supply and performance of fasteners exposed to corrosive or outdoor environments.

Related Standards

ASTM F2329/F2329M references and works together with several other applicable ASTM standards, including:

• ASTM A153/A153M - Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware
• ASTM A394 - Specification for Steel Transmission Tower Bolts, Zinc-Coated and Bare
• ASTM A563/A563M - Specification for Carbon and Alloy Steel Nuts
• ASTM A780/A780M - Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings
• ASTM B487 - Test Method for Measurement of Metal and Oxide Coating Thickness
• ASTM E376 - Practice for Measuring Coating Thickness by Magnetic-Field or Eddy Current Methods
• ASTM F606/F606M - Test Methods for Mechanical Properties of Fasteners
• ASTM F1470 - Guide for Fastener Sampling
• ASTM F1789 - Terminology for Mechanical Fasteners

These referenced documents support comprehensive quality assurance and interoperability across international projects and supply chains.

Keywords: hot-dip zinc coating, galvanized fasteners, steel bolts, steel nuts, zinc coating requirements, ASTM F2329, corrosion resistant fasteners, coating thickness, mechanical fasteners, alloy steel fasteners, zinc repair, fastener standards.

Standards Content (Sample)

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 [e-mail]. 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 temperi
...