NATIONAL BUREAU OF STANDARDS REPORT

59^3

FIREPROOFING STRUCTURAL STEEL

by

E. W. Bender

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

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NATIONAL BUREAU OF STANDARDS REPORT

MBS PROJECT MBS REPORT

1002-20-4875 June 25, 1958 59^3

FIREPROOFING STRUCTURAL STEEL

By

E. ¥. Bender

Report to

Office of the Chief of Engineers

Bureau of Yards and Docks

Headquarters U. S. Air Force

IMPORTANT NOTICE

NATIONAL BUREAU OF ST/

Intended for use within the 1 tc additional evaluation and r listing of this Report, either i the Office of the Director, Na

however, by the Government

to reproduce additional cople

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

progress accounting documents

irmally published It is subjected

, reproduction, or open-literature

islon Is obtained In writing from Such permission Is not needed,

f prepared if that agency wlshe*

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

FIREPROOFING STRUCTURAL STEEL

ABSTRACT

Work has been continued on an investigation of the effectiveness of fire-retardant materials sprayed directly on structural

steel members. Data on the performance of 1-in, thick coatings of

a number of such materials are presented. Similar data on 1/2-in.

thick coatings of the materials have been reported previously.

1.

INTRODUCTION

The need for information on the effectiveness of available

fire-retardant materials which can be sprayed directly on structural steelwork, and the results of fire tests on specimens

protected by 1/2-in. thick coatings, were presented in NBS Report

No. 5821, dated March 27, 1958* The present report provides data

on the performance of the same fire-retardant materials applied

in coatings 1-in. thick.

2.

MATERIALS

The fire-retar.dant materials included in the investigation,

and the preparation of the fire test specimens, were described

in NBS Report No. 5821.

In addition to fire exposure tests conducted as described in

the previous report, thermal conductivity measurements also were

made on the 1-in. thickness of the materials. Two specimens of

each material were prepared for these conductivity measurements

by spray-filling wooden frames having inside dimensions of 8x8x1 in. , and lined with polyethylene film to prevent

sticking of the fire-retardant to the wood-. The specimens were

removed from the frames for test,

3.

METHODS OF TEST

The method of performing the fire exposure tests has been

fully described in the previous report, No. 5821.

The thermal conductivity measurements were made in an 8-in.

guarded hot-plate apparatus conforming with the requirements of

Federal Specification LLL-F-321b and of ASTM Standard 0177-^5-

The specimens were air-dried to constant weight in an oven at

2l5°F immediately prior to the conductivity measurements.
2

k* RESULTS

The density, weight per sq ft for 1-in. application, and

time to reach lOOOa F on the steel plate are given in Table 1.

The materials are listed in order of performance in the fire

test, that with the longest average endurance being listed first.

The results of the thermal conductivity tests are given in

Table 2. The materials are listed in order of performance, that

with the lowest conductivity listed first.

5. DISCUSSION

The results obtained with the materials, in both 1/2-in.

and 1-in. thickness, are shown graphically In Figure 1, where

endurance or time required for the steel plate to reach. 10QlQ°Z

Is plotted against density in lbs/ft-l. The curves show an appreciable difference in relative behavior of the materials for the

two thicknesses of the fibrous specimens, but not for the vermiculite or the perlite and bentonite clay mixtures. In spite of

these differences, the curves indicate that, generally, the fire

endurance varied with the density of the material. A few of the

materials showed some deviation from this relationship which was

not entirely consistent for the two thicknesses. However, the

material consisting entirely of asbestos fibers, showed, at both

thicknesses, greater fire endurance for a given density than the

other materials tested.

The fire endurance data given in this report may be used in

estimating the protection which might be obtained for a roof,

floor, or ceiling section. Predictions of the endurance of

columns, beams, or braces from these data is not simple, although

it is expected that some estimates of this type may be feasible

with the use of the analog computer. The endurance of 2-In.

thick materials will be reported when the tests are finished.

6. CONCLUSIONS

Eight materials when applied in a 1-in. thickness, continued

to bond to the steel plate for the -duration of the fire exposure.

The results indicate that these eight materials show some merit

for use as fire-protective coverings when applied directly to

steel work.
TABLE 1

Fire Test Results on Specimens with One-Inch Fireproofing

Finish on Weight Time

Manufacturer Plate and for Steel Plate Fiber

and Specimen 1-in. reached or

Material Number Density Thickness 1000°F Mineral

lbs/ft3 lbs/ft2 Min

' Rat ’ 1 Gypsum Go • Thermocoustic Unpainted 9 20.10 1„£8 135 Glass &

do Unpainted 10 22.35 1.86 170 Asbestos

do Shop-coated 63 18.39 1.53 77

do Shoo-coated 64 21.69 1.8l 200

Aver as

e

20.63 1.72 " T4fD

U. S. Gypsum Co • Audicote Unpainted 51 19.59 1.63 164 Perlite &

do Unpainted 52 19-17 1.60 170 Asbestos

do Shop-coated 106 17.73 1.48 75

do Shop-coated 105 20.43 1.70 ...75 __ Aver as

e

19.23 1.60

" 121

Columbia

Acoustics & Unpainted 3 19'. 08 1.59 126 All Glass

Fireproofing Co .Unpainted 4 18.48 1.54 155

Cafco Spray Shop-coated 57 15.30 1.27 58

Standard Fiber Shon-coated 58 19.89 1.66 .80

Aver as

e

18.19 1.52

' 1 65

'

Keasbey & Matti son

Co.

Limpet Unpainted 27 9.75 .81 78 All

do Unpainted 28 10.53 .88 90 Asbestos

do Shop-coated 81 12.27 1.02 110

do Shou-coated 82 11.11 .93 85 _ Averase 10.92 .91 9.1 Larson Products

Plaster Weld Unpainted 45 53.52 4.46 75 Perlite

do Unpainted 46 53.82 4.48 163 Asbestos

N< do Shop-coated 99 42.96 3.58 65 Gypsum

do Shou-coated 100 39 .5.7 3.29 56

Averase 47.47 3.95 90

Zon-O-Lite Co.

Zon-O-Lite Unpainted 39 18.21 1.52 93 Vermiculite

Acoustical Unpainted 4o 18.21 1.52 75 and

Plastic Shop-coated 93 15.84 1.32 55 Asbestos

do Shou-coated 94 16.05 ; 1.34 60

Averase 17.08 1.42 71
TABLE 1 (continued)

Manufacturer

and

Material

Finish on

Plate and

Specimen

Number Density

Weight

for

1-in.

Thickness

Time

Steel Plate

reached

1000°F

Fiber

or -

1 Mineral

lbs/ft* lbs/ft^ Min

Smith & Kanzler Glass

Jetbestos Inc. Unpainted 33 13.56 1.13 91 and

Spray Craft Unpainted 34 14. 28 1.19 74 Asbestos

do Shop-coated 87 14. 07 1.17 70

do Shoe-coated 88 14.76 1.21 50

Average 14.17 1.18 ._ _ 71...

Air-0- Therm

Application Co.. Unpainted 15 16.80 1.40 68 All

Jet-Sulation Unpainted 16 15.96 1.33 68 Glass

do Shop-coated 69 15.57 1.30 47

do Shou-coated 70 23.34 1.94 47

Average 17.92 1.49 £8
DENSITY, POUNDS PER CUBIC FOOT

FIG. I- FIRE ENDURANCE
TABLE 2

Results of Thermal Conductivity Measurements

Mean Temperature Loss of

Manufacturer

and

Material

Density

as

Tested

Temperature

of

Specimens

Gradient

in

Specimens

Weight

on

Drying

Thickness

as

Tested

Thermal

Conduxrtrylty

Ib'/ftT" op °F/im. % 1-in. —3TTT/hr/ftV

°F/in.

Air-O-Therm

Application

Co.

Jet-Sulation

20.0 73.6 43.0 1-9 1.01 0.33

Nat'l Gypsum

Co.

Thermocoustic

20.8 73.6 5-2.5 0.8 1.02 0.35-

Keasbey &

Mattison Co.

Limpet

12.5 73-8 5-5-.. 5- 2.5 0.99 0.35

Columbia

Acoustics &

Fireproofing

Co.

Cafco Spray

19.8 73.9 5-1.5- 0.9 1.06 0.43

Smith &

Kanzler

Jetbestos Inc

Spray Craft

20.8

•

73o 9 43.7 0.9 1.01 0.5-8

Zon-O-Lite Co

Acoustical

Plastic

. 15.8 73.8 48.6 2.2 0.89 0.65

U. S. Gypsum

Co.

Audicote

18 .

5

73.6 43.8 1.8 0.99 0.68

Larson

Products

5-6.1 73.8 43.5 13.5-* 1.00 0.79

Plasterweld

Gypsum Perlite

Acoustic Plaster

*At the prescribed drying temperature the gypsum was partially calcinedo

USCOMM- NBS-DC
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretory

NATIONAL BUREAU OF STANDARDS

A. V. Asl in. Director THE NATIONAL BUREAU OF STANDARDS

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