Fire Resistance of Aluminum and Aluminum Alloys on the

ASM InternationalMaterials Park, OH 44073-0002

asminternational.org

J. Gilbert Kaufman

Fire Resistance of Aluminum and Aluminum Alloys

Measuring the Effects of Fire Exposure on the Properties of Aluminum Alloys&

Copyright © 2016 by

ASM International® All rights reserved

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First printing, June 2016

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Fire Resistance of Aluminum and Aluminum Alloys and Copyright © 2016 ASM International®

Measuring the Effects of Fire Exposure on the Properties of Aluminum Alloys All rights reservedJ.G. Kaufman asminternational.org

iii

Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v

About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vii

Chapter 1Properties and Characteristics of Aluminum

and Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Melting of Aluminum and its Alloys . . . . . . . . . . . . . . . . . . . . . . . 11.2 Mechanical Properties of Aluminum Alloys

at High Temperatures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 Physical Properties of Aluminum Alloys. . . . . . . . . . . . . . . . . . . . 21.4 Resistance to Burning in Normal Atmospheric Conditions. . . . . . 41.5 Burning in Pure Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.6 Resistance to and Protection from Thermic Sparking . . . . . . . . . . 6

Chapter 2Fire Protection of Aluminum Structures . . . . . . . . . . . . . . . . . . . 11

2.1 Vermiculite Encasement for Fire Protection . . . . . . . . . . . . . . . . .112.2 Rockwool Insulation for Fire Protection of Aluminum Naval

Bulkheads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.3 General Guidelines for Fire Protection of Ship Structures . . . . . 192.4 Other Options for Fire Protection of Aluminum Structures . . . . 20

Chapter 3Aluminum in Fire-Sensitive Applications . . . . . . . . . . . . . . . . . . . 23

3.1 Offshore Oil Rigs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.2 Building Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.3 Over-the-Road Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.4 Railroad Cars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

iv / Fire Resistance of Aluminum and Aluminum Alloys

3.5 Commercial Ships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293.6 Naval Vessels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Chapter4Estimating the Properties of Aluminum Alloys Exposed to Fire . . 37

4.1 Hardness Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374.2 Electrical Conductivity Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 454.3 Summary of Findings Regarding Estimate of Fire D amage . . . . 49

Chapter 5Applications Not Recommended for Aluminum Alloys . . . . . . . . 51

Chapter 6Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

APPENDIX 1Elevated Temperature Tensile Properties

of Representative Alloys* . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

APPENDIX 2Physical Properties of Aluminum and Aluminum Alloys . . . . . . . 95

APPENDIX 3Representative Fire Test Reports for Aluminum Alloys. . . . . . . . 107

APPENDIX 4Fire Protection for Aluminum Alloy Structural Shapes . . . . . . . 119

Limiting Temperatures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120Two columns tested . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120Test procedure and results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

APPENDIX 5ALFED Fact Sheet 3 Alumium and Fire . . . . . . . . . . . . . . . . . . . 125

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125Aluminum in a Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127Aluminum in Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127Aluminum in Marine and Offshore Applications . . . . . . . . . . . . . . 129

Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131



v

Preface

Aluminum melts at approximately 660 ° C (1220 ° F), lower than most common structural metals such as iron and steel. Because of this, its be-havior in fires can lead to confusion about its performance. Work was expended on this publication to document facts about the fire resistance of aluminum and aluminum alloys, and to enable engineers and designers to take account of aluminum’s characteristic high resistance to burning while recognizing its relatively low melting point. The information includes facts with corresponding references; speculation and subj ectivity are excluded.

Other publications have provided very useful technical data and guid-ance concerning some aspects of dealing with the characteristics of alumi-num alloys with respect to fire exposure, but none has provided the full scope of coverage contained here.

The author gratefully acknowledges the support of the Aluminum As-sociation, Inc. for access to its publications and photographs, the support of Alcoa, Inc. for access to previously unpublished data for aluminum al-loys included herein, and to ASM International.



vi

About the Author

John Gilbert (Gil) Kaufman has a background of over 50 years in the aluminum and materials information industries and remains an active con-sultant in both areas. In 1997, he retired as Vice President, Technology for the Aluminum Association, Inc., headqua rtered then in Washington, D .C. (now in Arlington, Va.), and is currently president of his own consultancy, Kaufman Associates.

Earlier in his career, Kaufman spent 26 years with the Aluminum Com-pany of America, where he managed engineering properties and fabricat-ing metallurgical research at Alcoa Laboratories. Many of the data presented in this volume were generated over the period when the author was active in and/ or managing Alcoa Laboratories engineering properties research.

Kaufman subsequently spent five years with ARCO Metals, where he was D irector of R& D and, later, Vice President, Research & Engineering. Kaufman also served for nine years as President and CEO of the National Materials Property D ata Net-work where, working with STN International and Chemical Ab-stracts Service, he established a worldwide online network of more than 25 numeric materials properties databases.

Gil is a Fellow and Honorary Member of ASTM and a Fellow and Life Member of ASM Inter-national. He is a licensed profes-sional engineer in D elaware. Gil has published more than 140 ar-ticles and six books on alumi-num alloys and materials data systems.

vii



Introduction

The natural physical characteristics of aluminum and its alloys are such that they do not burn under normal atmospheric conditions nor do they contribute to flame spread or act as a fire accelerant. The data supporting these statements are provided in detail in the following chapters. Other organizations have addressed various aspects of this subj ect qui te well (Ref 1–6), but none has addressed the whole scope of relevant material as attempted here.

The performance of aluminum alloys is excellent in many applications requi ring exposure to relatively high temperatures, including (a) personal and commercial vehicles of many kinds, (b) marine applications such as fast ferry hulls and oil drilling rigs where superior corrosion resistance is critical, and (c) a variety of structural applications such as buildings, bridges, and pressure vessels. More details about the importance of alumi-num’s high resistance to burning in some of these applications is discussed.

Because aluminum melts at a temperature of approximately 655 ° C, or 1200 ° F (Ref 7, 8), lower than most common structural metals such as iron and steel, its behavior in some structural situations can lead to misunder-standings about its performance in fires. For example, when vehicles such as cars, trucks, or ships with aluminum components are caught in an en-gulfing fire, the aluminum components may be reported to have burned because they appear to combust and burn away. In fact, the aluminum components melt and run off, giving the appearance of being consumed in the fire. Aluminum or aluminum alloy components do not burn or contrib-ute to the combustion.

Misunderstandings about aluminum behavior in fires has occurred in the past. For example, during the Falklands War in 1982, it was widely reported that the British warship HMS Sheffield was destroyed by Argen-tine rockets because the ship was made largely of aluminum and had com-busted; in fact, the Sheffield was made entirely of steel and its destruction had nothing to do with aluminum (Ref 9).

viii / Fire Resistance of Aluminum and Aluminum Alloys

It is the purpose of this book to describe the facts regarding the behav-ior of aluminum at very high temperatures, including those as high as or higher than necessary to cause it to melt, and to characterize its behavior in a wide range of applications where high-temperature performance is important. The behavior described is based entirely on documented test data, primarily the results of tests made in accordance with ASTM Stan-dard Methods (Ref 10–12) and British Standards (Ref 13–17) .

Consideration is also given to situations where aluminum alloys have been exposed to fire but not melted and there is a subsequent need to esti-mate the residual strength of the exposed members. Although aluminum alloys lose strength when exposed to temperatures above approximately 100 ° C, or 212 ° F (Ref 18), they do not deform until temperatures near 500 to 600 ° C (800 to 900 ° F) are reached. Engineers must be able to de-termine whether aluminum alloy components that have had exposure to fire are able to continue to function satisfactorily or if performance has been compromised. By using nondestructive tests such as hardness and electrical conductivity measurements, it is possible to estimate with con-siderable accuracy the retained mechanical strength. Tools are included herein to guide estimates of this type.

There are, of course, applications where the high-temperature exposure is too great for aluminum to be used due to its low melting temperature. These are also documented, and guidance is provided for decisions on whether or not to use aluminum alloys in new applications.

The facts concerning the fire resistance of aluminum are:

• The physical properties of aluminum, notably high thermal conductiv-ity, specific heat, and reflectance and its low emissivity, provide resis-tance to structures against temperature rise comparable or superior to that provided by steels in the early stages or in a non-engulfing fire.

• Even when temperatures do increase to intense incendiary levels, alu-minum does not burn in air nor will it support combustion. When tested in accordance with ASTM or British standards, aluminum pro-vides the highest ratings for resisting flame spread because it is not easily ignitable under atmospheric conditions and does not support flame spread.

• When necessary, the structural integrity of aluminum alloy structures can be protected against fire by practical and commercial fireproofing technology such as lightweight vermiculite concrete, similar to that used to fire protect steels, or Rockwool or gypsum sheeting.

• Aluminum is nonsparking in all environments and with all materials, with one known exception: when bare (unpainted or uncoated) alumi-num is struck by or strikes rusty ferrous metals, sparks may result.

• Under conditions where it is likely or possible that aluminum may be struck by rusty ferrous metals, protective coatings such as paint are recommended to avoid any possibility of sparking.

Introduction / ix

REFERENCES

1. J.A. Purkiss and L.-Y . Li, F ire Saf ety Engineering D esign of Struc -tur es, 3r d ed., CRC Press, New Y ork, 2013

2. B. Faggiano, G. D e Matteis, R. Landolfo, and F.M. Mazzolani, Be-haviour of Aluminium Structures Under Fire, J . Civ. Eng. M anag.,Vol X (No. 3) , 2002, p 183–190

3. M.J. Bayley, The Fire Protection of Aluminium in Offshore Struc-tures, eed f he e l e h l ee

e h fe e e e l d e e Me-chanical Engineering Publications, London, 1992, p 113–120

4. S. Lundberg, “ Material Aspects of Fire D esign,” TALAT Lecture 2502, European Aluminium Association, 1994

5. “ Fire Resistance and Flame Spread Performance of Aluminum and Aluminum Alloys,” Standard AA FRFS, 2nd ed., The Aluminum Association, Washington, D .C., July 2002

6. Fire Resistance of Aluminum, l d he Se Alcan Alu-minium Company, 2013

7. l S d d d The Aluminum Association, Arlington, VA, 2013

8. l S d d d e S The Aluminum As-sociation, Arlington, VA, 2013

9. “ The Falklands Campaign: The Lessons,” presented to Parliament by the Secretary of D efence by Command of Her Maj esty, D ec 1982

10. “ Standard Methods of Fire Tests of Roof Coverings,” ASTM E108, l f S S d d ASTM (updated annually)

11. “ Standard Test Methods for Fire Tests of Building Construction and Materials,” ASTM E119, Part 04.07, l f S S -d d ASTM (updated annually)

12. “ Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750 ° C,” ASTM E136, l f S S d dASTM (updated annually)

13. Classification of Materials for Fire Resistance, Part 3: External Fire Exposure Roof Test,” British Standard 476, The British Standards Institution, 1975

14. Classification of Materials for Fire Resistance, Part 4: Non-com-bustibility Test for Materials,” British Standard 476, The British Standards Institution, 1970

15. Classification of Materials for Fire Resistance, Part 5: Ignitability of Building Materials” (now replaced by Part 4), British Standard 476, The British Standards Institution

16. Classification of Materials for Fire Resistance, Part 6: Fire Com-bustibility of Coated Systems” (now obsolete), British Standard 476, The British Standards Institution

17. Classification of Materials for Fire Resistance, Part 23: Methods for D etermination of the Contribution of Components to the Fire

x / Fire Resistance of Aluminum and Aluminum Alloys

Resistance of a Structure,” British Standard 476, The British Stan-dards Institution

18. J.G. Kaufman, e e f l ll e le ee de h d e e e ASM International,

Materials Park, OH, 1999

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Fire Resistance of Aluminum and Aluminum Alloys on the