ASTM A394-08(2024)

Standard Specification for Steel Transmission Tower Bolts, Zinc-Coated and Bare

ABSTRACT
This specification covers the chemical and mechanical requirements of hexagon and square-head zinc-coated steel bolts and atmospheric corrosion-resistant bolts for use in the construction of transmission towers, substations, and similar steel structures. The following types of bolts are: Type 0 includes hot-dip zinc-coated bolts made of low or medium carbon steel, Type 1 includes hot-dip zinc-coated bolts made of medium carbon steel, quenched and tempered, Type 2, and Type 3 includes bare, quenched, and tempered bolts made of weathering steel. Steel for the manufacture of bolts shall be made by any of the following processes: open-hearth, electric-furnace, or basic-oxygen. Type 1 bolts produced from medium carbon steel shall be quenched in a liquid medium from above the austenizing temperature. Type 1 bolts produced from medium carbon steel to which chromium, nickel, molybdenum, or boron were intentionally added shall be quenched only in oil from above the austenitizing temperature. Type 3 bolts shall be quenched only in oil from above the austenitizing temperature. Cold-headed Type 0 bolts shall be stress relief annealed before zinc coating to remove cold work effects such that the hardness measured anywhere on the surface or through the cross-section shall meet the requirement specified. Different tests shall be conducted in order to determine the following mechanical properties of bolts: hardness, tensile strength, and shear strength.
SCOPE
1.1 This specification covers the chemical and mechanical requirements of hexagon and square-head zinc-coated steel bolts and atmospheric corrosion-resistant bolts, in nominal thread diameters of 1/2 , 5/8 , 3/4 , 7/8 and 1 in. for use in the construction of transmission towers, substations, and similar steel structures. The various types of bolts covered in this specification are:  
1.1.1 Type 0—Hot-dip zinc-coated bolts made of low or medium carbon steel.  
1.1.2 Type 1—Hot-dip zinc-coated bolts made of medium carbon steel, quenched and tempered.  
1.1.3 Type 2—Withdrawn in 2005.  
1.1.4 Type 3—Bare (uncoated), quenched and tempered bolts made of weathering steel.  
1.2 Annex A1 of this specification covers hot-dip zinc-coated steel ladder bolts, step bolts, and support-equipment bolts.  
1.3 Nuts and washers that are supplied under this specification that are hot-dip zinc coated shall be in accordance with 4.4.  
1.4 Terms used in this specification are defined in Terminology F1789.  
1.5 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6 The following safety hazards caveat pertains only to the test methods portion, Section 11, of this specification. 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.  
1.7 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-Dec-2023
• ICS: 21.060.10 - Bolts, screws, studs
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: F16 - Fasteners
• Drafting Committee: F16.02 - Steel Bolts, Studs and Nuts

Relations

• Replaces: ASTM A394-08(2015) - Standard Specification for Steel Transmission Tower Bolts, Zinc-Coated and Bare
• Effective Date: 01-Jan-2024
• Refers: ASTM F1470-24 - Standard Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
• Effective Date: 01-Jan-2024
• Refers: ASTM F1470-19 - Standard Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
• Effective Date: 01-Aug-2019
• Referred By: ASTM A563/A563M-23 - Standard Specification for Carbon and Alloy Steel Nuts (Inch and Metric)
• Effective Date: 01-Jan-2024
• Referred By: 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
• Effective Date: 01-Jan-2024
• Referred By: ASTM F606/F606M-21 - Standard Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets
• Effective Date: 01-Jan-2024

Overview

ASTM A394-08(2024) is the internationally recognized standard specification for steel transmission tower bolts, both zinc-coated and bare. Published by ASTM International, this standard details the chemical and mechanical requirements for hexagon and square-head zinc-coated steel bolts, as well as atmospheric corrosion-resistant bolts, primarily used in the construction of transmission towers, substations, and related steel structures. This specification covers bolts with nominal thread diameters of 1/2, 5/8, 3/4, 7/8, and 1 inch, ensuring performance and reliability for critical infrastructure projects.

Key Topics

• Bolt Types Covered

  • Type 0: Hot-dip zinc-coated bolts made from low to medium carbon steel, offering corrosion protection.
  • Type 1: Hot-dip zinc-coated, quenched, and tempered bolts made from medium carbon steel.
  • Type 3: Bare, quenched, and tempered bolts constructed from weathering steel for enhanced atmospheric corrosion resistance.

• Mechanical and Chemical Requirements

  • Specifies strict requirements for chemical composition, mechanical properties (tensile strength, shear strength, and hardness), and manufacturing processes for each bolt type.
  • Inspects bolts for surface discontinuities and ensures dimensional accuracy.

• Heat Treatment and Coating

  • Details heat treatment procedures for various bolt types, including quenching and tempering.
  • Outlines the application of hot-dip zinc coatings to provide corrosion resistance, referencing thickness and weight standards for effective protection.

• Associated Fasteners

  • Recommends compatible nuts and washers, including requirements for zinc-coated finishes and mechanical properties to match bolt specifications.

• Testing and Quality Assurance

  • Requires comprehensive lot testing, inspections, and certification for every production lot.
  • Specifies methods for hardness, tensile, shear, and coating thickness testing to ensure compliance.

Applications

ASTM A394-08(2024) is essential for industries involved in:

• Electric Power Transmission and Distribution:
  • Used in the assembly of transmission towers, substations, and support structures where reliability against mechanical stress and atmospheric exposure is vital.
• Communications Infrastructure:
  • Applied in the construction of telecommunication masts and towers needing robust bolt performance.
• Heavy Steel Structures:
  • Relevant for bridges, lighting poles, and other exposed steel frameworks requiring weather-resistant fasteners.

Compliance with ASTM A394 ensures long-term structural stability, safety, and resistance to corrosion for infrastructure operating under varying environmental conditions.

Related Standards

To meet all design, procurement, and installation challenges, ASTM A394 references several key standards:

• ASTM A563: Specification for carbon and alloy steel nuts, essential for matching nuts to bolt types and finishes.
• ASTM F436: Standard for hardened steel washers, providing adequate support and stress distribution.
• ASTM F2329: Specification detailing requirements for hot-dip zinc coatings on fasteners.
• ASTM F606/F606M: Test methods for determining mechanical properties of fasteners.
• ASME B1.1: Unified screw threads standard, ensuring thread compatibility and uniformity.
• ASME B18.2.1: Dimensions for square and hex bolts and screws.

For users specifying or procuring fasteners for transmission towers and related steel structures, referencing ASTM A394-08(2024) ensures high-quality, consistent, and internationally compliant products, supporting both safety and performance in critical infrastructure applications.

Keywords: ASTM A394, transmission tower bolts, zinc-coated bolts, steel bolts standard, weathering steel, hot-dip zinc coating, substation fasteners, mechanical properties, corrosion-resistant bolts, power infrastructure fasteners.

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: A394 − 08 (Reapproved 2024)
Standard Specification for
Steel Transmission Tower Bolts, Zinc-Coated and Bare
This standard is issued under the fixed designation A394; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This specification covers the chemical and mechanical
mendations issued by the World Trade Organization Technical
requirements of hexagon and square-head zinc-coated steel
Barriers to Trade (TBT) Committee.
bolts and atmospheric corrosion-resistant bolts, in nominal
1 5 3 7
thread diameters of ⁄2, ⁄8, ⁄4 , ⁄8 and 1 in. for use in the
2. Referenced Documents
construction of transmission towers, substations, and similar
2.1 ASTM Standards:
steel structures. The various types of bolts covered in this
A563 Specification for Carbon and Alloy Steel Nuts (Metric)
specification are:
A0563_A0563M
1.1.1 Type 0—Hot-dip zinc-coated bolts made of low or
D3951 Practice for Commercial Packaging
medium carbon steel.
F436 Specification for Hardened Steel Washers (Metric)
1.1.2 Type 1—Hot-dip zinc-coated bolts made of medium
F0436_F0436M
carbon steel, quenched and tempered.
F606/F606M Test Methods for Determining the Mechanical
1.1.3 Type 2—Withdrawn in 2005.
Properties of Externally and Internally Threaded
1.1.4 Type 3—Bare (uncoated), quenched and tempered
Fasteners, Washers, Direct Tension Indicators, and Rivets
bolts made of weathering steel.
F788/F788M Specification for Surface Discontinuities of
1.2 Annex A1 of this specification covers hot-dip zinc-
Bolts, Screws, Studs, and Rivets, Inch and Metric Series
coated steel ladder bolts, step bolts, and support-equipment
F1470 Practice for Fastener Sampling for Specified Me-
bolts.
chanical Properties and Performance Inspection
1.3 Nuts and washers that are supplied under this specifica-
F1789 Terminology for F16 Mechanical Fasteners
tion that are hot-dip zinc coated shall be in accordance with
F2329 Specification for Zinc Coating, Hot-Dip, Require-
4.4.
ments for Application to Carbon and Alloy Steel Bolts,
Screws, Washers, Nuts, and Special Threaded Fasteners
1.4 Terms used in this specification are defined in Termi-
G101 Guide for Estimating the Atmospheric Corrosion Re-
nology F1789.
sistance of Low-Alloy Steels
1.5 The values stated in inch-pound units are to be regarded
2.2 ASME Standards:
as standard. No other units of measurement are included in this
B1.1 Unified Screw Threads
standard.
B18.2.1 Square and Hex Bolts and Screws
1.6 The following safety hazards caveat pertains only to the
B18.24 Part Identifying Number (PIN) Code System Stan-
test methods portion, Section 11, of this specification. This
dard for B18 Fastener Products
standard does not purport to address all of the safety concerns,
if any, associated with its use. It is the responsibility of the user
3. Ordering Information
of this standard to establish appropriate safety, health, and
3.1 Orders for products under this specification shall include
environmental practices and determine the applicability of
the following:
regulatory limitations prior to use.
3.1.1 Quantity (number of bolts and accessories).
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This specification is under the jurisdiction of ASTM Committee F16 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Fasteners and is the direct responsibility of Subcommittee F16.02 on Steel Bolts, Standards volume information, refer to the standard’s Document Summary page on
Studs and Nuts. the ASTM website.
Current edition approved Jan. 1, 2024. Published January 2024. Originally Available from American Society of Mechanical Engineers (ASME), ASME
approved in 1955. Last previous edition approved in 2015 as A394 – 08 (2015). International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
DOI: 10.1520/A0394-08R24. www.asme.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
A394 − 08 (2024)
3.1.2 Name of products, including accessories such as A563 intentionally added shall be quenched only in oil from above
nuts and F436 washers when desired. the austenitizing temperature.
3.1.3 Dimensions, including nominal bolt diameter and
4.2.2 Type 3 bolts shall be quenched only in oil from above
length. For bolts other than transmission-tower bolts, complete
the austenitizing temperature.
dimensions are required (see Annex A1).
4.2.3 Type 1 bolts, regardless of the steel used, and Type 3
3.1.4 Type of bolt (for example, Type 0, 1, or 3).
bolts shall be tempered by reheating to not less than 800 °F.
3.1.4.1 When non-zinc-coated atmospheric corrosion-
4.2.4 Cold-headed Type 0 bolts shall be stress relief an-
resistant steel is required, Type 3 bolts shall be specified by the
nealed before zinc coating to remove cold work effects such
purchaser.
that the hardness measured anywhere on the surface or through
3.1.5 ASTM designation and year of issue. When year of
the cross-section shall meet the requirements in 6.1.
issue is not specified, bolts shall be furnished to the latest issue.
4.3 Threads may be rolled or cut.
3.1.6 Additional requirements, if any, are to be specified on
the purchase order:
4.4 Zinc Coatings, Hot Dip:
3.1.6.1 Shear-strength testing (see 6.2.1 and 6.2.2). Include
4.4.1 Type 0 and Type 1 bolts shall be hot-dip zinc-coated
type of test required.
accordance with the requirements of Specification F2329,
3.1.6.2 Additional tests.
except that the minimum average weight (thickness) of zinc
3.1.6.3 Inspection (see 12.1 and 12.2).
coating shall be 1.65 oz/ft (0.0028 in.) and the minimum
3.1.6.4 Certification (see 14.1).
weight of zinc coating on any one item shall be 1.50 oz/ft
3.1.6.5 Test reports (see 14.1).
(0.0025 in.).
3.1.6.6 Other finishes, specify other protective finish, if
4.4.2 Bolt threads shall not be cut, rolled, or otherwise
required.
finished after zinc coating.
4.4.3 Hot-dip zinc-coated nuts furnished under Specifica-
NOTE 1—Examples of ordering description:
(1) 1000 square-head transmission-tower bolts, ⁄2 by 2 in. Type 1, hot-dip
tion A563 shall be tapped after zinc coating.
zinc coated, shear testing required, ASTM A394 – XX, with hot-dip
4.4.4 Hot-dip zinc-coated nuts and washers supplied for use
zinc-coated hex nuts, Grade DH, ASTM A563 – XX,
with bolts under this specification shall be zinc-coated in
(2) 1000 transmission tower bolts, ⁄2 by 2 in. Type 0, hot-dip zinc coated,
accordance with 4.4.1.
ASTM A394 – XX, with hot-dip zinc-coated hex nuts, Grade A, ASTM
A563 – XX.
4.5 Protection of Uncoated Surfaces—When hot-dip zinc-
(3) 1000 transmission tower bolts, ⁄2 by 2 in. Type 3, ASTM A394 – XX,
coated nuts are ordered, the cutting oil or some other suitable
with hex nuts, Grade DH3 weathering steel, ASTM A563 – XX and with
substance shall be left on the uncoated surface to inhibit rusting
2 circular washers, Type 3, ASTM F436 – XX.
during shipment and storage. It is recommended that the
3.1.7 For establishment of a part identifying system, see
additional lubricant be clean and dry to the touch.
ASME B18.24.
4.6 Secondary Processing:
3.2 Recommended Nuts:
4.6.1 If any processing which can affect the mechanical
3.2.1 Unless otherwise specified, all nuts on these bolts shall
properties or performance of the bolts is performed after the
be hex style and conform to the requirements of Specification
initial testing, the bolts shall be retested for all specified
A563 as follows.
mechanical properties and performance requirements affected
Bolt Type Nut Grade Finish
0 A hot-dip zinc-coated by the reprocessing.
1 DH hot-dip zinc-coated
4.6.2 When the secondary processing is heat treatment, the
3 DH3 plain
bolts shall be tested for all specified mechanical properties.
3.3 Recommended Washers:
Hot-dip zinc-coated bolts shall be tested for all specified
3.3.1 Suitable washers for use with Type 0 are hot-dip
mechanical properties.
zinc-coated carbon-steel washers with dimensions that are in
accordance with Specification F436. Suitable washers for use
5. Chemical Composition
with Type 1 bolts are hot-dip zinc-coated Type 1 hardened-steel
5.1 Type 0 and Type 1 bolts shall conform to the chemical
washers that are in accordance with Specification F436. Suit-
composition requirements specified in Table 1.
able washers for use with Type 3 bolts are Type 3 hardened-
steel washers that are in accordance with Specification F436.
5.2 Type 3 bolts shall conform to one of the chemical
compositions specified in Table 2. The selection of the chemi-
4. Materials and Manufacture
cal composition A, B, C, D, E, or F shall be at the option of the
bolt manufacturer. See Guide G101 for methods of estimating
4.1 Steel for the manufacture of bolts shall be made by any
the atmospheric corrosion resistance of low alloy steels.
of the following processes: open-hearth, electric-furnace, or
basic-oxygen.
6. Mechanical Properties
4.2 Heat Treatment:
4.2.1 Type 1 bolts produced from medium carbon steel shall 6.1 Tension Test—Types 0, 1, and 3 bolts having a length
be quenched in a liquid medium from above the austenizing equal to or more than 3 diameters shall be wedge tension tested
temperature. Type 1 bolts produced from medium carbon steel as specified in 11.1 and shall conform to the tensile strength
to which chromium, nickel, molybdenum, or boron were requirements in Table 3. Zinc-coated bolts shall be tested after
A394 − 08 (2024)
TABLE 1 Chemical Requirements and Head Markings
Element, %
Head Marking Bolt Type
Carbon Manganese Phosphorus Sulfur Boron
0 0.55 max . . . 0.048 max 0.058 max . . .
1 0.28/0.55 0.60 min 0.048 max 0.058 max . . .
3 . . . . . . . . . See Table 2 . . .
A
TABLE 2 Chemical Requirements for Type 3 Heavy Hex Structural Bolts
Composition, %
A
Element Type 3 Bolts
A B C D E F
Carbon:
Heat Analysis 0.33–0.40 0.38–0.48 0.15–0.25 0.15–0.25 0.20–0.25 0.20–0.25
Product Analysis 0.31–0.42 0.36–0.50 0.14–0.26 0.14–0.26 0.18–0.27 0.19–0.26
Manganese:
Heat Analysis 0.90–1.20 0.70–0.90 0.80–1.35 0.40–1.20 0.60–1.00 0.90–1.20
Product Analysis 0.86–1.24 0.67–0.93 0.76–1.39 0.36–1.24 0.56–1.04 0.86–1.24
Phosphorus:
Heat Analysis 0.035 max 0.06–0.125 0.035 max 0.035 max 0.035 max 0.035 max
Product Analysis 0.040 max 0.06–1.25 0.040 max 0.040 max 0.040 max 0.040 max
Sulfur:
Heat Analysis 0.040 max 0.040 max 0.040 max 0.040 max 0.040 max 0.040 max
Product Analysis 0.045 max 0.045 max 0.045 max 0.045 max 0.045 max 0.045 max
Silicon:
Heat Analysis 0.15–0.35 0.30–0.50 0.15–0.35 0.25–0.50 0.15–0.35 0.15–0.35
Product Analysis 0.13–0.37 0.25–0.55 0.13–0.37 0.20–0.55 0.13–0.37 0.13–0.37
Copper:
Heat Analysis 0.25–0.45 0.20–0.40 0.20–0.50 0.30–0.50 0.30–0.60 0.20–0.40
Product Analysis 0.22–0.48 0.17–0.43 0.17–0.53 0.27–0.53 0.27–0.63 0.17–0.43
Nickel:
Heat Analysis 0.25–0.45 0.50–0.80 0.25–0.50 0.50–0.80 0.30–0.60 0.20–0.40
Product Analysis 0.22–0.48 0.47–0.83 0.22–0.53 0.47–0.83 0.27–0.63 0.17–0.43
Chromium:
Heat Analysis 0.45–0.65 0.50–0.75 0.30–0.50 0.50–1.00 0.60–0.90 0.45–0.65
Product Analysis 0.42–0.68 0.47–0.83 0.27–0.53 0.45–1.05 0.55–0.95 0.42–0.68
Vanadium:
B B B B B
Heat Analysis 0.020 min
B B B B B
Product Analysis 0.010 min
Molybdenum:
B B B B
Heat Analysis 0.06 max 0.10 max
B B B B
Product Analysis 0.07 max 0.11 max
Titanium: . . . . . .
B B B B B
Heat Analysis 0.05 max
B B B B B
Product Analysis 0.06 max
A
A, B, C, D, E, and F are classes of material used for Type 3 bolts. Selection of a class shall be at the option of the bolt manufacturer.
B
These elements are not specified or required.
A
TABLE 3 Tensile Strength
coating. Bolts too short for full size testing or for other reasons
Nominal Minimum Tensile Load, lbf
not subject to tension tests, shall meet the following hardness
Size, B C
Type 0 Types 1 and 3
requirements:
in.
⁄2 10 500 17 050
Min Max
⁄8 16 700 27 100
⁄4 24 700 40 100
Type 0—Rockwell B 80 100
⁄8 34 200 55 450
Types 1 and 3—Rockwell C 25 34
1 44 850 72 700
6.2 Shear Strength:
A
Tensile strength based on the thread stress area, A , is calculated as follows:
s
6.2.1 When specified in the original inquiry and order, bolts,
A = 0.7854 [ D − (0.9743/N)]
s
except as excluded in 6.2.2, shall be shear strength tested in
where:
D = nominal diameter, and
accordance with 11.2 and shall meet the requirements given in
N = threads per inch.
Table 4.
B
Based on 74 000 psi unit tensile strength.
C
6.2.2 Bolts with unthreaded body lengths shorter than two Based on 120 000 psi unit tensile strength.
times the nominal bolt diameter, are subject to shear strength
A394 − 08 (2024)
TABLE 4 Shear Strengths
A
Nominal Bolt Oversize Limit, in.
Diameter, in.
Minimum Load, lbf
Hot-Dip Zinc
Type 0 Types 1 and 3
⁄2 0.018
Single Shear Single Shear Single Shear Single Shear
Nominal Size, 5 3
⁄8 , ⁄4 0.
...