ASTM Bolt Specifications

The American Society for Testing and Materials, is an international standards organization that develops and publishes

voluntary consensus technical standards for a wide range of materials, products, systems, and services.

A153 - Hot dip galvanizing specification.

A193 - Alloy steel and stainless steel bolting materials for high temperature service.

A194 - Carbon and alloy nuts for bolts for high pressure and high temperature service.

A307 - Carbon steel bolts and studs ranging from 1/4" through 4" diameter.

A320 - Alloy steel and stainless steel bolting materials for low temperature service.

A325 - Structural bolts, steel, heat treated, 120/105 ksi minimum tensile strength.

A354 - Quenched and tempered alloy bolts, studs, and other externally threaded fasteners.

A449 - Quenched and tempered steel bolts and studs.

A490 - Structural bolts, alloy steel, heat treated, 150 ksi tensile strength.

A563 - Standard specification for carbon and alloy steel nuts.

F1554 - Anchor bolts designed to anchor structural supports to concrete foundations.

F2329 - New specification covering hot dip galvanizing.

ASTM A153

Quick Links

Galvanizing

FAQ: Galvanizing High Strength Bolts

FAQ: Galvanized Nuts Tapped Oversize

Scope

The ASTM A153 specification covers zinc coating (hot-dip) on iron and steel hardware. A newer and more appropriate

specification developed in 2005 covering the requirement for hot-dip galvanizing of bolts, screws, nuts, washers and other

threaded fasteners is ASTM F2329. It is not yet widely used since many of the ASTM specifications covering bolts, nuts and

washers do not reference it. As soon as revisions referencing F2329 are made to these fastener specifications, F2329 will

become more common. ASTM A123 is a related hot-dip galvanizing specification covering iron and steel products made

from rolled pressed and forged shapes, castings, plates, bars, and strips. The equivalent AASHTO specification to ASTM

A153 is AASHTO M232.

ASTM A193

Quick Links

Hex Bolts

A193 All Thread Rod

ASTM A194

Thread Pitch Chart

Scope

Originally approved in 1936, this specification is heavily utilized in petroleum and chemical construction applications. The

ASTM standard covers alloy steel and stainless steel bolting materials for high temperature or high pressure service. This

specification includes fasteners intended for use in pressure vessels, valves, flanges, and fittings. Although, this material is

often available in national coarse (UNC) thread pitches, if being used in traditional applications, threads are specified 8

threads per inch (tpi) for diameters above one inch.

Below is a basic summary of a few of the common grades. ASTM A193 covers a number of other standard specifications not

covered in this description including B5, B6, and B16.

Grades

B7 Alloy steel, AISI 4140/4142 quenched and tempered

B8 Class 1 Stainless steel, AISI 304, carbide solution treated.

B8M Class 1 Stainless steel, AISI 316, carbide solution treated.

B8 Class 2 Stainless steel, AISI 304, carbide solution treated, strain hardened

B8M Class 2 Stainless steel, AISI 316, carbide solution treated, strain hardened

Mechanical Properties

Grade Size Tensile ksi, min Yield, ksi, min Elong, %, min RA % min

B7

Up to 2-1/2 125 105 16 50

2-5/8 - 4 115 95 16 50

4-1/8 - 7 100 75 18 50

B8 Class 1 All 75 30 30 50

B8M Class 1 All 75 30 30 50

B8 Class 2

Up to 3/4 125 100 12 35

7/8 - 1 115 80 15 35

1-1/8 - 1-1/4 105 65 20 35

1-3/8 - 1-1/2 100 50 28 45

Grade Size Tensile ksi, min Yield, ksi, min Elong, %, min RA % min

B8M Class 2

Up to 3/4 110 95 15 45

7/8 - 1 100 80 20 45

1-1/8 - 1-1/4 95 65 25 45

1-3/8 - 1-1/2 90 50 30 45

Recommended Nuts and Washers

Bolt Grade Nuts Washers

B7 A194 Grade 2H F436

B8 Class 1 A194 Grade 8 SS304

B8M Class 1 A194 Grade 8M SS316

B8 Class 2 A194 Grade 8 SS304

B8M Class 2 A194 Grade 8M SS316

Strain hardened nuts available as a supplementary requirement

ASTM A194

Quick Links

Heavy Hex Bolts

ASTM A193

Nut Weight Chart

Scope

The ASTM A194 specification covers carbon, alloy and stainless steel nuts intended for use in high-pressure and/or high-

temperature service. Unless otherwise specified, the American National Standard Heavy Hex Series (ANSI B 18.2.2) shall

be used. Nuts up to and including 1 inch nominal size shall be UNC Series Class 2B fit. Nuts over 1 inch nominal size shall

be either UNC Series Class 2B fit or 8 UN Series Class 2B fit. High strength ASTM A194 grade 2H nuts are common in the

marketplace and are often substituted for ASTM A563 grade DH nuts due to the limited availability of DH nuts in certain

diameters and finishes.

Grades

2 Carbon steel heavy hex nuts

2H Quenched & tempered carbon steel heavy hex nuts

2HM Quenched & tempered carbon steel heavy hex nuts

4 Quenched & tempered carbon-molybdenum heavy hex nuts

7 Quenched & tempered alloy steel heavy hex nuts

7M Quenched & tempered alloy steel heavy hex nuts

8 Stainless AISI 304 heavy hex nuts

8M Stainless AISI 316 heavy hex nuts

Mechanical Properties Grade Identification Markings

Grade

Identification

Marking5

Specification Material Nominal

Size, In.

Tempering

Temp. °F

Proof

Load

Stress,

ksi

Hardness

Rockwell See

Note Min Max

ASTM A194

Grade 2

Medium

Carbon

Steel

1/4 - 4 1000 150 159 352 1,2,3

ASTM A194

Grade 2H

Medium

Carbon

Steel,

Quenched

and

Tempered

1/4 - 4 1000 175 C24 C38 1,2

ASTM A194

Grade 2HM

Medium

Carbon

Steel,

Quenched

and

1/4 - 4 1000 150 159 237 1,2,3

Tempered

ASTM A194

Grade 4

Medium

Carbon

Alloy

Steel,

Quenched

and

Tempered

1/4 - 4 1100 175 C24 C38 1,2

ASTM A194

Grade 7

Medium

Carbon

Alloy

Steel,

Quenched

and

Tempered

1/4 - 4 1100 175 C24 C38 1,2

ASTM A194

Grade 7M

Medium

Carbon

Alloy

Steel,

Quenched

and

Tempered

1/4 - 4 1100 150 159 237 1,2,3

ASTM A194

Grade 8

Stainless

AISI 304 1/4 - 4 - 80 126 300 4

ASTM A194

Grade 8M

Stainless

AISI 316 1/4 - 4 - 80 126 300 4

NOTES:

1. The markings shown for all grades of A194 nuts are for cold formed and hot forged nuts. When nuts are machined from bar stock, the nut must additionally be marked with the

letter 'B'. The letters H and M indicate heat treated nuts. 2. Properties shown are those of coarse and 8-pitch thread heavy hex nuts. 3. Hardness numbers are Brinell Hardness. 4. Nuts that are carbide-solution treated require additional letter A - 8A or 8MA. 5. All nuts shall bear the manufacturer’s identification mark. Nuts shall be legibly marked on

one face to indicate the grade and process of the manufacturer. Marking of wrench flats or bearing surfaces is not permitted unless agreed upon between manufacturer and purchaser. Nuts coated with zinc have an asterisk (*) marked after the grade symbol. Nuts coated with cadmium shall have a plus sign (+) marked after the grade symbol.

6. Other less common grades exist, but are not listed here.

Inch Fastener Standards. 7th ed. Cleveland: Industrial Fasteners Institute, 2003. N-80 - N-81.

ASTM A307

Quick Links

Hex Bolts

Bent Anchor Bolts

A307 All Thread Rod

ASTM A563 Hex Nuts

Scope

The ASTM A307 specification covers carbon steel bolts and studs ranging from 1/4” through 4” diameter. This is your

everyday, run of the mill bolt specification often manufactured using A36 round bar. There are three grades A, B, and C*

which denote tensile strength, configuration, and application. Refer to the Mechanical Properties Chart for the subtle

strength differences within each grade.

Grades

A Headed bolts, threaded rods and bent bolts intended for general applications.

B Heavy hex bolts and studs intended for flanged joints in piping systems with cast iron flanges.

C* Nonheaded anchor bolts, either bent or straight, intended for structural anchorage purposes. The

end of a grade C anchor bolt intended to project from the concrete will be painted green for

identification purposes. Permanent marking is a supplemental requirement. *As of August 2007,

grade C has been replaced by specification F1554 grade 36. We will continue to supply grade C, if

required by the project.

Mechanical Properties

Grade Tensile, ksi Yield, min, ksi Elong %, min

A 60 min -- 18

B 60 - 100 -- 18

C* 58 - 80 36 23

Recommended Nuts and Washers

Nuts

Washers A307 Grades A & C* A307 Grade B

1/4 - 1-1/2 1-5/8 - 4 1/4 - 4

A563A Hex A563A Heavy Hex A563A Heavy Hex F844

ASTM A320

Quick Links

Heavy Hex Bolts

ASTM A193

Strength by Grade

Scope

Originally approved in 1948, the ASTM A320 specification covers alloy steel and stainless steel bolting materials for low

temperature service. This standard covers rolled, forged, or strain hardened bars, bolts, screws, studs, and stud bolts used

for pressure vessels, valves, flanges, and fittings. Like the ASTM A193 specification, unless otherwise specified, the 8UN

thread series is specified on fastener larger than 1” in diameter.

Below is a basic summary of a few of the common grades within the ASTM A320 specification. A number of other less

common grades of ASTM A320 exist, but not covered in the description below.

Grades

L7 Alloy steel AISI 4140/4142 Quenched and tempered

L43 Alloy steel AISI 4340 Quenched and tempered

B8 Class 1 Stainless steel AISI 304, carbide solution treated

B8M Class 1 Stainless steel AISI 316, carbide solution treated

B8 Class 2 Stainless steel AISI 304, carbide solution treated, strain hardened

B8M Class 2 Stainless steel AISI 316, carbide solution treated, strain hardened

Mechanical Properties

Grade Size Tensile,

ksi, min

Yield,

ksi, min

Charpy Impact

20-ft-lbf

@ temp

Elong,

%, min RA, %, min

L7 Up to 21/2 125 105 -150° F 16 50

L43 Up to 4 125 105 -150° F 16 50

B8

Class 1 All 75 30 N/A 30 50

B8M

Class 1 All 75 30 N/A 30 50

B8

Class 2

Up to 3/4 125 100 N/A 12 35

7/8 - 1 115 80 N/A 15 35

11/8 - 11/4 105 65 N/A 20 35

13/8 - 11/2 100 50 N/A 28 45

B8M

Class 2

Up to 3/4 110 95 N/A 15 45

7/8 - 1 100 80 N/A 20 45

11/8 - 11/4 95 65 N/A 25 45

13/8 - 11/2 90 50 N/A 30 45

Recommended Nuts and Washers

Grade Nuts Washers

L7 A194 Grade 4 or 7 F436

L43 A194 Grade 4 or 7 F436

B8 Class 1 A194 Grade 8 SS304

B8M Class 1 A194 Grade 8M SS316

B8 Class 2 A194 Grade 8, strain hardened SS304

B8M Class 2 A194 Grade 8M, strain hardened SS316

ASTM A325

Quick Links

DTI Washer

Large Diameter A325

Rotational Capacity

Bolt Torque Chart

Scope

The ASTM A325 specification covers high strength heavy hex structural bolts from ½” diameter through 1-1/2” diameter.

These bolts are intended for use in structural connections and therefore have shorter thread lengths than standard hex bolts.

Refer to the Structural Bolts page of our site for thread lengths and other related dimensions.

This specification is applicable to heavy hex structural bolts only. For bolts of other configurations and thread lengths with

similar mechanical properties, see Specification A 449.

Bolts for general applications, including anchor bolts, are covered by Specification A 449. Also refer to Specification A 449

for quenched and tempered steel bolts and studs with diameters greater than 1-1/2" but with similar mechanical properties.

Types

TYPE 1 Medium carbon, carbon boron, or medium carbon alloy steel.

TYPE 2 Withdrawn November 1991.

TYPE 3 Weathering steel.

T Fully threaded A325. (Restricted to 4 times the diameter in length)

M Metric A325.

Connection Types

SC Slip critical connection.

N Bearing type connection with threads included in the shear plane.

X Bearing-type connection with threads excluded from the shear plane.

Mechanical Properties

Size Tensile, ksi Yield, ksi Elong. %, min RA %, min

1/2 - 1 120 min 92 min 14 35

1-1/8 - 1-1/2 105 min 81 min 14 35

Recommended Nuts and Washers

Nuts Washers

Type 1 Type 3 Type 1 Type 3

Plain Galvanized Plain

A563C, C3, D, DH, DH3 A563DH A563C3, DH3 F436-1 F436-3

Note: Nuts conforming to A194 Grade 2H are a suitable substitute for use with A325 heavy hex

structural bolts. The ASTM A563 Nut Compatibility Chart has a complete list of specifications.

ASTM A354

Quick Links

Hex Bolts

Anchor Rods

Strength by Grade

Scope

The ASTM A354 specification covers the chemical and mechanical requirements of quenched and tempered alloy steel

bolts, studs, and other externally threaded fasteners 4" and under in diameter.

Two strength levels, grade BC and grade BD, are summarized in the chart below. This specification is unrestricted in its

configuration and can be a headed bolt, bent bolt, or threaded rod.

Grades

A354

BD

A354 grade BD bolts are higher in strength than A354 grade BC and equal in strength to

ASTM A490 bolts. Unlike ASTM A490 however, the A354 BD specification is

unrestricted in its configuration. Since A490 bolts are heavy hex structural bolts and do

not exceed 1-1/2" diameter, specification A354 BD should be considered for anchor bolts,

threaded rods, other styles of headed bolts, and bolts larger than 1-1/2" diameter where

similar mechanical properties are desired. A354 grade BD does not require a magnetic

particle test as is required by the A490 specification.

Research conducted on bolts of similar material and manufacture indicates that hydrogen-

stress cracking or stress cracking corrosion may occur on hot-dip galvanized Grade BD

bolts. For more information about this subject, please see our FAQ that

addresses galvanizing of high strength bolts.

A354

BC

Lower in strength than grade BD.

Mechanical Properties

Grade Size Tensile, ksi, min Yield, ksi, min Elong %, min RA %, min

BC 1/4 - 2-1/2 125 109 16 50

2-5/8 - 4 115 99 16 45

BD 1/4 - 2-1/2 150 130 14 40

2-5/8 - 4 140 115 14 40

Recommended Nuts and Washers

Nuts

Washers Grade BC Grade BD

Plain Galvanized Plain

A563C Heavy Hex A563DH Heavy Hex A563DH Heavy Hex F436

* Nuts of other grades load stresses greater than the specified grade are suitable. Follow the link for

an ASTM A563 Nut Compatibility Chart.

ASTM A449

Quick Links

Thread Pitch Chart

Ask the Expert

Bolt Torque Chart

Scope

ASTM A449 covers headed bolts, rods, and anchor bolts in diameters ranging from 1/4" through

3" inclusive. It is a medium strength bolt manufactured from a medium carbon or alloy steel that

develops its mechanical values through a heat treating process. It is intended for general

engineering applications.

ASTM A449 is virtually identical in chemistry and strength to ASTM A325 and SAE J429 grade

5. However, A449 is more flexible in the sense that it covers a larger diameter range and is not

restricted by a specific configuration.

TYPES

TYPE 1 Plain carbon steel, carbon boron steel, alloy steel, or alloy boron steel.

TYPE 2 Withdrawn 2003

TYPE 3 Weathering steel.

MECHANICAL PROPERTIES

Size Tensile, ksi Yield, ksi Elong. %, min RA %, min

1/4 - 1 120 min 92 min 14 35

1-1/8 - 1-1/2 105 min 81 min 14 35

1-5/8 - 3 90 min 58 min 14 35

RECOMMENDED NUTS and WASHERS

Nuts

Washers Plain Galvanized

1/4 - 1-1/2 1-5/8 - 3 1/4 - 3

A563B Hex A563A Heavy Hex A563DH Heavy Hex F436

Note: Nuts of other grades having proof load stresses greater than the specified grade are suitable.

The ASTM A563 Nut Compatibility Chart has a complete list of specifications.

ASTM A490

Quick Links

DTI Washer

Bolt Glossary

Bolt Torque Chart

Scope

The ASTM A490 specification covers quenched and tempered, alloy steel, heavy hex structural bolts from ½” diameter

through 1½” diameter with a minimum 150 ksi tensile. These bolts are intended for use in structural connections and

therefore have shorter thread lengths than standard hex bolts. Refer to the Structural Bolts page of our site for thread

lengths and other related dimensions. A490 bolts are similar in application and dimensions to A325 heavy hex structural

bolts but are made from an alloy steel rather than a medium carbon steel, resulting in a higher strength fastener.

The A490 specification is applicable to heavy hex structural bolts only. For bolts with different thread lengths than specified

for structural bolts but with similar mechanical properties, see Specification A354 grade BD.

ASTM A490 bolts shall not be coated by hot-dip galvanizing, mechanical deposition, or electroplating with zinc or other

metallic coatings due to the potential risk of hydrogen embrittlement.

Additional testing in the form of Magnetic Particle Inspection for Longitudinal Discontinuities and Transverse Cracks is a

requirement of the A490 specification.

Types

TYPE 1 Medium carbon and alloy steel.

TYPE 2 Withdrawn in 2002.

TYPE 3 Weathering steel.

M Metric A490.

Connection Types

SC Slip critical connection.

N Bearing type connection with threads included in the shear plane.

X Bearing type connection with threads excluded from the shear plane.

Mechanical Properties

Size Tensile, ksi Yield, ksi Elong. %, min RA %, min

1/2 - 1-1/2 150-173 130 14 40

Recommended Nuts and Washers

Nuts Washers

Type 1 Type 3 Type 1 Type 3

A563DH A563DH3 F436-1 F436-3

Note: Nuts conforming to A194 Grade 2H are a suitable substitute for use with A490 heavy hex structural bolts. Follow the

link for anASTM A563 Nut Compatibility Chart.

Notes

1. The bolts shall not be coated by hot-dip zinc coating, mechanical deposition, or electroplating with zinc or other

metallic coatings due to the potential for hydrogen embrittlement. Read more about issues with galvanizing ASTM

A490.

2. Each sample representative of the lot shall be magnetic particle inspected for longitudinal discontinuities and

transverse cracks.

ASTM A563

Quick Links

Thread Pitch Chart

Ask the Expert

Bolt Torque Chart

The ASTM A563 specification covers the chemical and mechanical requirements for carbon and alloy steel nuts used on

bolts, studs, and externally threaded fasteners. The charts below address over tapping allowances for hot-dip galvanized

nuts, grade marking requirements, and mechanical requirements. For information on suitable nuts for various grades of

bolts, visit theNut Compatibility Chart.

According the A563 specification, "The requirements for any grade of nut may, at the supplier's option, and with notice to the

purchaser, be fulfilled by furnishing nuts of one of the stronger grades specified herein unless such a substitution is barred in

the inquiry and purchase order". This is important because some nut grades are not readily available in certain sizes and

finishes. Additionally, the specification allows for the substitution of ASTM A194 grade 2H nuts in lieu of A563 grade DH nuts

due to the lack of availability of grade DH nuts in nominal sizes ¾" and larger.

Hot-dip galvanized nuts must be tapped oversize to allow for the added thickness of the zinc on the threads of the externally

threaded fastener. These allowances are addressed in the chart below and a more detailed explanation of this issue can be

found in theFrequently Asked Questions section of this site.

Various nut styles exist and to some degree are determined by their grade. These styles include hex, heavy

hex, square, jam, coupling, and sleeve.

Scope

Standard specification for carbon and alloy steel nuts.

Grades A Low carbon steel, hex or heavy hex

B Low carbon steel, hex or heavy hex

C Carbon steel, quenched and tempered, heavy hex

D Carbon steel, quenched and tempered, heavy hex

DH Carbon steel, quenched and tempered, heavy hex

C3 Weathering steel, quenched and tempered, heavy hex

DH3 Weathering steel, quenched and tempered, heavy hex

Mechanical Properties

Grade Style Size, in.

Proof Load, ksi

Hardness, HBN

Black Galvanized

A

Hex 1/4 - 1-1/2 90 68 116 - 302

Heavy Hex 1/4 - 4 100 75 116 - 302

B

Heavy Hex 1/4 - 1 133 100 121 - 302

Heavy Hex 1-1/8 - 1-1/2 116 87 121 - 302

C / C3 Heavy Hex 1/4 - 4 144 144 143 - 352

D Heavy Hex 1/4 - 4 150 150 248 - 352

DH / DH3 Heavy Hex 1/4 - 4 175 150 248 - 352

For UNC, 8UN, 6UN, and Coarse Pitch Threads

Grade Identification Markings

Grade Identification

Marking Specification Material

Nominal

Size, In.

Proof Load

Stress, ksi

Hardness

Rockwell See

Note

Min Max

No Mark

ASTM A563

Grade O Carbon Steel 1/4 - 1-1/2 69 B55 C32 2,3

ASTM A563

Grade A Carbon Steel 1/4 - 1-1/2 90 B68 C32 2,3

ASTM A563

Grade B Carbon Steel

1/4 - 1 120

B69 C32 2,3

>1 - 1-1/2 105

ASTM A563

Grade C

Carbon Steel, may be

Quenched and Tempered 1/4 - 4 144 B78 C38 4

ASTM A563

Grade C3

Atmospheric Corrosion

Resistant Steel, may be

Quenched and Tempered

1/4 - 4 144 B78 38 4,6

ASTM A563

Grade D

Carbon Steel, may be

Quenched and Tempered 1/4 - 4 150 B84 C38 5

ASTM A563

Grade DH

Carbon Steel, Quenched and

Tempered 1/4 - 4 175 C24 C38 5

ASTM A563

Grade DH3

Atmospheric Corrosion

Resistant Steel, Quenched

and Tempered

1/4 - 4 175 C24 C38 4,6

NOTES:

1. In addition to the indicated grade marking, all grades, except A563 grades O, A, and B, must be marked for

manufacturer identification.

2. Nuts are not required to be marked unless specified by the purchaser. When marked, the identification marking

shall be the grade letter O, A, or B.

3. Properties shown are those of nonplated or noncoated coarse thread nuts.

4. Properties shown are those of coarse thread heavy hex nuts.

5. Properties shown are those of coarse thread heavy hex nuts. Other nuts styles and fine threads may apply.

6. The nut manufacturer, at his option, may add other markings to indicate the use of atmospheric corrosion

resistant steel.

Inch Fastener Standards. 7th ed. Cleveland: Industrial Fasteners Institute, 2003. n-80-n-81.

Thread Dimensions and Oversizing Allowances

for Nuts: Hot Dipped Galvanized per Specification A153, C1.C

Nominal Nut Size, in. and Pitch Diametral Allowance, in.

Pitch Diameter

Min Max

0.250 - 20 0.016 0.2335 0.2384

0.312 - 18 0.017 0.2934 0.2987

0.375 - 16 0.017 0.3514 0.3571

0.437 - 14 0.018 0.4091 0.4152

0.500 - 13 0.018 0.4680 0.4745

0.0562 - 12 0.020 0.5284 0.5352

0.625 - 11 0.020 0.5860 0.5932

0.750 - 10 0.020 0.7050 0.7127

0.875 - 9 0.022 0.8248 0.8330

Nominal Nut Size, in. and Pitch Diametral Allowance, in.

Pitch Diameter

Min Max

1.000 - 8 0.024 0.9428 0.9516

1.125 - 8 0.024 1.0678 1.0768

1.125 - 7 0.024 1.0562 1.0656

1.250 - 8 0.024 1.1928 1.2020

1.250 - 7 0.024 1.1812 1.1908

1.375 - 8 0.027 1.3208 1.3301

1.375 - 6 0.027 1.2937 1.3041

1.500 - 8 0.027 1.4458 1.4553

1.500 - 6 0.027 1.4187 1.4292

1.750 - 5 0.050 1.6701 1.6817

2.000 - 4.5 0.050 1.9057 1.9181

2.250 - 4.5 0.050 2.1557 2.1683

2.500 - 4 0.050 2.3876 2.4011

2.750 - 4 0.050 2.6376 2.6513

3.000 - 4 0.050 2.8876 2.9015

3.250 - 4 0.050 3.1376 3.1517

3.500 - 4 0.050 3.3876 3.4019

3.750 - 4 0.050 3.6376 3.6521

4.000 - 4 0.050 3.8876 3.9023

Inch Fastener Standards. 7th ed. Cleveland: Industrial Fasteners Institute, 2003. B-173.

ASTM F1554

Quick Links

Anchor Rods

ASTM A449

Strength by Grade

Scope

The ASTM F1554 specification was introduced in 1994 and covers anchor bolts designed to anchor structural supports to

concrete foundations. F1554 anchor bolts can take the form of either headed bolts, straight rods, or bent anchor bolts. The

three grades 36, 55, and 105 designate the minimum yield strength (ksi) of the anchor bolt. The bolts can be either cut or roll

threaded and a weldable grade 55 can be substituted for grade 36 at the supplier’s option. Color coding on the end - 36

blue, 55 yellow, and 105 red – helps facilitate easy identification in the field. Permanent manufacturer and grade marking is

allowed under the S2 supplementary requirements.

Applications for F1554 anchor bolts include columns in structural steel framed buildings, traffic signal and street lighting

poles, and overhead highway sign structures to name just a few.

Grades

F1554 Grade 36 Low carbon, 36 ksi yield steel anchor bolts

F1554 Grade 55 High strength, low alloy, 55 ksi yield steel anchor bolts

F1554 Grade 105 Alloy, heat treated, high strength 105 ksi yield steel anchor bolts

Mechanical Properties

Grade Marking Size

inches

Tensile,

ksi

Yield, ksi

min

Yield, MPa

min

Elong. %

min

RA %

min

36

1⁄4 - 4 58 - 80 36 248 23 40

55

1⁄4 - 2 75 - 95 55 380 21 30

21⁄4 - 21⁄2 75 - 95 55 380 21 22

23⁄4 - 3 75 - 95 55 380 21 20

31⁄4 - 4 75 - 95 55 380 21 18

105

1⁄4 - 3 125 - 150 105 724 15 45

Stamping of F1554 bolts with manufacturer's identification is a supplemental requirement (S2)

Color coding is required unless the grade is stamped in accordance with supplemental requirement (S3).

When Grade 36 is specified, a weldable Grade 55 may be furnished at the supplier's option.

Recommended Nuts and Washers

Grade Size inches Nuts

Washer Plain Galvanized

36

1⁄4 - 11⁄2 A563A Hex A563A Hex F436

13⁄4 - 4 A563A Heavy Hex A563A Heavy Hex F436

55

1⁄4 - 11⁄2 A563A Hex A563A Heavy Hex F436

13⁄4 - 4 A563A Heavy Hex A563A Heavy Hex F436

105

1⁄4 - 11⁄2 A563D Heavy Hex¹ A563DH Heavy Hex² F436

13⁄4 - 3 A563DH Heavy Hex² A563DH Heavy Hex² F436

1. A563-D rarely available, A563DH or A194-2H substituted. 2. Per ASTM A563, A194-2H may be substituted for A563-DH.

ASTM F2329

Quick Links

Galvanizing Capabilities

FAQ - Galvanizing High Strength

FAQ - Galvanized Nuts

Scope

ASTM F2329 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. This specification was developed in 2005, but

is not yet widely used since many of the ASTM specification covering threaded fasteners do not reference it. As soon as

these specifications are updated to reference the ASTM F2329 specification, it will likely become much more prevalent

than ASTM A153 which is the specification that is currently used to cover hot-dip galvanizing of bolts. ASTM A123 is a

related hot-dip galvanizing specification covering iron and steel products made from rolled pressed and forged shapes,

castings, plates, bars, and strips.

Galvanizing High Strength Bolts

Question: Can high strength bolts be hot-dip galvanized?

Answer: Some high strength bolts can be galvanized while others cannot. In the construction fastener industry, typically the

phrase “high strength” refers to bolts that have been quenched and tempered (heat treated) to develop the proper strength

requirements of a given specification. Two separate issues are involved in determining whether or not a high strength bolt

can be galvanized.

Hydrogen Embrittlement Concerns

The first issue involves a phenomenon called hydrogen embrittlement which may occur when atomic hydrogen is absorbed

by the steel during the acid pickling process that takes place prior to galvanizing. This embrittlement can potentially lead to

the loss or partial loss of ductility in the steel and consequently result in the premature failure of the fastener in the field.

According to specification ASTM A143 – Safeguarding Against Embrittlement of Hot-Dip Galvanized Structural Steel

Products and Procedure for Detecting Embrittlement:

“In practice hydrogen embrittlement of galvanized steel is usually of concern only if the steel exceeds approximately 150 ksi

(1100 MPa) in ultimate tensile strength.”

Additionally, section 7.2.2 of specification ASTM F2329 – Zinc Coating, Hot-Dip, Requirements for Application to Carbon

and Alloy Steel Bolts, Screws, Washers, Nuts, and Special Threaded Fasteners reads as follows:

“For high strength fasteners (having a specified minimum product hardness of 33 HRC), there is a risk of internal hydrogen

embrittlement.”

By reviewing Table 1 below, it is clear that specifications ASTM A490, ASTM A354 grade BD, and SAE J429 grade 8 are all

potentially susceptible to hydrogen embrittlement and should therefore not be hot-dip galvanized. This is further reinforced

by specific references found in both the ASTM A490 specification and the ASTM A354 specification. According to section

4.3 – Protective Coatings of specification ASTM A490:

“The bolts shall not be coated by hot-dip zinc coating, mechanical deposition, or electroplating with zinc or other metallic

coatings.”

Similarly, Note 4 in section 4 of specification ASTM A354 reads as follows:

“Research conducted on bolts of similar material and manufacture indicates that hydrogen-stress cracking or stress cracking

corrosion may occur on hot-dip galvanized Grade BD bolts.”

This information taken directly from the ASTM specifications supports the belief that hot-dip galvanizing of ASTM A490,

ASTM A354 grade BD, and SAE J429 grade 8 should be avoided due to the risk of hydrogen embrittlement.

Which Bolt Grades Can Be Galvanized?

Grade Can I

Galvanize?

Raw

material Nominal Size

Minimum

Yield

Strength

Minimum

Tensile

Strength

Minimum

Hardness

ASTM A325 Yes Medium

Carbon

Steel,

Quenched

and

Tempered

1/2″ – 1″

1 1/8″ – 1 1/2″

92

81

120

105

C24

C19

ASTM A449 Yes

1/4″ – 1″

1 1/8″ – 1 1/2″

1 5/8″ – 3″

92

81

58

120

105

90

C25

C19

B91

SAE J429 Grade 5 Yes 1/4″ – 1″

1 1/8″ – 1 1/2″

92

81

120

105

C25

C19

ASTM A193 Grade B7 Yes

Medium

Carbon Alloy

Steel,

Quenched

and

Tempered

1/4″ – 2 1/2″

2 5/8″ – 4″

105

95

125

115 NA

ASTM A354 Grade BC Yes 1/4″ – 2 1/2″

2 5/8″ – 4″

109

94

125

115

C26

C22

ASTM F1554 Grade

105 Yes 1/4″ – 3″ 105 125 NA

ASTM A320 Grade L7 Yes 1/4″ – 2 1/2″ 105 125 NA

ASTM A490 No 1/2″ – 1 1/2″ 130 150 C33

ASTM A354 Grade BD No 1/4″ – 2 1/2″

2 5/8″ – 4″

130

115

150

140

C33

C31

SAE J429 Grade 8 No 1/4″ – 1 1/2″ 130 150 C3

Effect of Heat on Quenched and Tempered Fasteners

The second issue of concern when considering hot-dip galvanizing high strength fasteners is potentially reducing the

mechanical strengths due to the introduction of heat during the hot-dip galvanizing process. Portland Bolt operates its hot-

dip galvanizing tank at 840° Fahrenheit. Is this enough heat to potentially alter the strength of a quenched and tempered

fastener? In theory, the amount of heat that a high strength fastener is exposed to during the hot-dip galvanizing process

should not alter its mechanical properties.

It is obvious that the application of heat to a bolt that develops its strength through a heat treating process could adversely

affect the strength of the fastener. The question is, how much heat is necessary to potentially change the mechanical

properties? On page 4-4 of the Ninth Edition of the AISC Manual (American Institute of Steel Construction), the following

statement occurs:

“Anchor bolt material that is quenched and tempered (heat treated) should not be welded or heated.”

However, it does not address the amount of heat that should be avoided. Welding obviously applies a tremendous amount

of heat to the components being welded, whereas hot-dip galvanizing is performed at significantly lower temperatures.

Another reference that addresses the heating of high strength bolts (which occurs during hot-dip galvanizing) can be found

in the ASTM F1554 specification. Section 6.4.3 of the ASTM F1554 specification states:

“Hot bending performed on heat-treated bar stock shall not have the temperature come within 100°F (56°C) of the tempering

(stress relieve) temperature of the heat-treat process at any location during hot bending and shall be allowed to air cool after

bending.”

Although this statement refers to hot bending, it implies that any process (including galvanizing) that applies heat

approaching or exceeding the tempering temperature of a high strength bolt may potentially alter the mechanical properties

of the fastener and should therefore be avoided. However, galvanized bolts only remain in the zinc tank for a few minutes

and even though the surface temperature may approach 840°, it is unlikely that the entire fastener is heated to that

temperature. The most relevant reference found in any ASTM specification addressing the possibility of the hot-dip

galvanizing process altering the mechanical properties of a high strength fastener is found in section 7.2.1.2 of the new hot-

dip galvanizing specification ASTM F2329 which states:

“Testing for mechanical properties is not necessary if the galvanizing process is carried out at a lower temperature than the

stress relief or tempering temperature of the fasteners.”

This implies that the mechanical properties have the potential to be altered only if high strength bolts are tempered at

temperatures at or below the 840° temperature that the bolts are subjected to during hot-dip galvanizing. As Table 2

indicates below, the minimum tempering temperature for both ASTM A193 grade B7 and ASTM F1554 grade 105 is 1100°

Fahrenheit. Therefore, it is not possible for the galvanizing temperatures to exceed the tempering temperature for these

specifications. Although in theory it is possible for the other specifications to be tempered below the galvanizing

temperature, recent records indicate that the minimum tempering temperature used for any of these grades listed in Table 2

that Portland Bolt has manufactured is 950°. Therefore, hot-dip galvanizing performed by Portland Bolt on any of the high

strength bolt specifications listed in Table 2 will not adversely affect the strength of these fasteners.

Minimum Tempering Temperatures

ASTM Grade Minimum Tempering Temperature, Fahrenheit

A325 800°

A449 800°

A354 Grade BC 800°

A320 Grade L7 No Requirement

A193 Grade B7 1100°

F1554 Grade 105 1100°