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NATIONAL BUREAU OF STANDARDS REPORT 

7061 



FIRE TESTS OF A STEEL COLUMN 
and 


SUPPLEMENTARY SPECIMENS PROTECTED 

with <s>, °h 


GLASS-FIBER REINFORCED PAINT 




by 


U cy 'V 'ey 

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J . V . Ryan 


<|Jb|> 

U. S. DEPARTMENT OF COMMERCE 
NATIONAL BUREAU OF STANDARDS 


THE NATIONAL BUREAU OF STANDARDS 


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NATIONAL BUREAU OF STANDARDS REPORT 

NBS PROJECT MBS REPORT 

1002-12-10120 January 13 , 1961 7061 

FIRE TESTS OF A STEEL COLUMN 
and 

SUPPLEMENTARY SPECIMENS PROTECTED 
with 

GLASS-FIBER REINFORCED PAINT 

by 

J. V. Ryan 
Physicist 


Report to 

Office of the Chief of Engineers 
Bureau of Yards and Docjts 
Headquarters, U. S. Air Force 


IMPORTANT. NOTICE 

NATIONAL 8UREAU OF STANDARDS REPORTS are usually preliminary or progress accounting documents 
Intended for use within the Government. Before material In the reports Is formally published It Is subjected 
to additional evaluation and review. For this reason, the publication, reprinting, reproduction, or open-literature 
listing of this Report, either In whole or In part, Is not authorized unless permission Is obtained In writing from 
the Office of the Director, National Bureau of Standards, Washington 25, D. C. Such permission Is not needed, 
however, by the Government agency for which the Report has been specifically prepared If that agency wishes 
to reproduce additional copies for Its own use. 


<NBS> 

U. S. DEPARTMENT OF COMMERCE 


FIRE TESTS OF A STEEL COLUMN AND SUPPLEMENTARY SPECIMENS 
PROTECTED WITH GLASS-FIBER REINFORCED PAINT 


by 

J . V . Ryan 


ABSTRACT 

A system consisting of a blend of paint and 
glass fibers for use as a fire protective material 
sprayed on structural steel was evaluated by five 
small-scale tests plus one standard fire test of 
a 13-ft column# The effects of thickness and of 
an overcoat of paint alone were shown in the small 
tests . 


The particular column tested, with 3/I6 in. 
thickness of protective material, exhibited 57 min. 
fire endurance. 


1. INTRODUCTION 

Many large buildings consist of a steel frame plus an enclos- 
ing shell, with few, if any, partitions or columns other than those 
making up the enclosing structure. Recent fires have shown the 
severe damage to unprotected steel columns and roof trusses that 
may result from fires in buildings of this general design. This 
construction is particularly suitable, and widely used, for air- 
plane hangars. This report gives the results of tests to evaluate 
the effectiveness of a protective material that may be applied 
directly to steel members by spray techniques. 

2. MATERIAL 

The protective materials consisted of glass fibers and two 
paints. The first paint was SAF 303 Resin base Fire Retardant 
Paint. One sample was found to weigh 12.1 lb/gal. The second 
paint was SAF 202. One sample was found to weigh 11.*+ lb/gal. 

The glass fiber was provided by the applicator and no technical 
data were obtained. 

. The SAF 303 paint was applied by a special double-nozzle gun 
that hls-o ' chopped the glass f-uJerV to lengths intended'" -t'o ‘he about 
1-1/4 in. long and fed them into the paint just after it left the 
sprayer. It was possible to spray paint without glass fibers. 

The application to the specimens wad done by a professional painter 


2 


He first wet the surface with paint and then built up the desired 
thickness of the paint-glass fiber mixture by repeated coats. 

The material was tamped lightly between coats. The successive 
coats were applied as rapidly as the skill of the painter per- 
mitted, with no intentional delays to allow drying between coats 

On two specimens, an overcoat of SAF 202 was applied within 
one week after the 303 -fiber mixture had been built up to the 
desired thickness. The SAF 202 paint was sprayed on without 
the inclusion of glass fibers. 


Six specimens were prepared consecutively by the same crafts 
men. The specimens were one steel column and five steel plates. 
The column was a 6H20 section 13 ft long with flange stiffeners 
in the upper 3 ft. The steel plates were 2 ft square, of 16 gage 
hot rolled steel, spot-welded to a grid of 3 /*+ in* cold rolled 
steel plasterers' channels. The protective material was applied 
to the face of the plate opposite to that welded to the channel 
grid. The overcoat of SAF 202 was applied over the SAF 303"gl a ss 
fiber coat on two of these plate specimens, only, but not to the 
column. 

The thicknesses of the protective coats were measured, as 
were the weight per sq ft of the material on the flat plate 
specimens : 

Specimen Col Plate 1 PI 2 PI 3 PI A PI 5 


Note: Plates 1 and 3 were overcoated with SAF 202. 

The steel plate specimens were stored in a room maintained 
at 73°F and 50 per cent relative humidity until they reached con- 
stant weight. The first specimen was tested 53 bays after the 
application of the protective material, and the other four during 
the following week. 

The column specimen was stored in a room heated, when 
■necessary, to comfort eorfctftions for 10A days before test. It 
was not practical to determine the period of aging by weight 
measurements, but, based on the time required for the plate 
specimens, the column's protective coating was assumed to have 
been aged for a satisfactory period. 


3 . SPECIMENS 


Thickness, in. 3/16 
Weight , lb/ft 2 


.094 .112 .082 .O 83 .231 

.5^ -75 .52 .5^ 1A9 


- 3 - 


4. TEST METHODS 

Each specimen was tested in an appropriate furnace. The 
furnaces were gas fired and the fuel flow regulated automatically 
so that the average temperatures measured in the furnace chambers 
were as close as feasible to those specified in the standard time- 
temperature curve prescribed in ASTM E-119, which include: 1000°F 
at 5 min, 1300°F at 10 min, 1550°F at 30 min, 1700°F at 1 hr. 

4.1 Steel Plate Specimens 

Before each fire test, the protective coating on the steel 
plate was cut with a knife through to the plate at about 1 in. 
from the edges. This was done so that the tendency of the 
material to fall or to stay in place would not be affected by 
the edge support by the furnace. 

Each specimen was placed coated face down, to close the 
top of a small furnace designed to expose an area about 23 by 
23 in. Each was backed by a firebrick transducer and asbestos 
millboard laid on the steel channel grid. The edges of this 
assembly were insulated. Temperatures were measured by means 
of chromel-alumel thermocouples connected to self-balancing 
potentiometers. Thermocouples were attached to both faces of 
the transducer and the upper face of the steel plate specimen. 

The end point of each test was established as the attainment 
of 1000°F temperature at the thermocouple junction attached to 
the steel plate. 


4.2 Column 

The column specimen was placed in a furnace specifically 
designed for the fire exposure of such specimens. All but about 
the top 3 ft of the 13 -ft specimen was exposed to fire. The 
column was subjected to a load of 80750 14, computed on the basis 
of a stress of 17000 psi reduced for the actual length-to-radius 
ratio. Temperatures were measured by chromel-alumel thermocouples 
attached to the steel column before the protective materials were 
applied. Observations were made of the thermal elongation of the 
column and its subsequent deformation under load. The only 
applicable end point in such a test is failure of the column 
to sustain the applied load. 


- 4 - 

5. RESULTS 

5.1 Steel Plate Specimens 

The data from these tests consisted of temperature readings 
at 5 min intervals throughout each test. The results are 
simply the times at which 1000°F was reached on the steel plate. 
These times are tabulated below: 

Plate No. 12345 

Failure, min 47 59 47 44 70 

Examination after test indicated that the protective coat- 
ings had puffed up somewhat and had remained in place throughout 
each test. 

5.2 Column 

The protective coating on the column turned black within the 
first minute. It puffed up, continuing to do so until about 
20 min, at which time the maximum thickness was estimated at 2 in. 
The development of cracks in the coating accompanied the puffing. 
The column expanded as the temperature increased until the average 
at one level reached 1000°F, at 50 min. The column yielded under 
the load gradually for a few minutes and then rapidly. It was 
judged to have failed at 56 min. The applied load was removed 
then and the test stopped after the 1 hr temperature readings. 

Examination after test showed the protective material still 
in place. The column was bowed along most of its exposed length. 

The fire endurance of the column was limited by load 
failure at 56 min. The highest section average temperature was 
about 1125°F and the one point maximum about 1190°F. The control 
of the furnace was such that a correction of +1 min was applicable 
to the failure time. 

6. DISCUSSION 

Comparison among the steel plate specimens indicated that in- 
creased thickness of protective material lead to later failure 
by the criterion applied. The use of the SAF 202 overcoat lead 
to a slightly later failure than for a specimen without it, 
having essentially the same total thickness. 


- 5 - 


7. SUMMARY 

The results of the tests indicated that the material 
remained in place throughout fire exposure up to 1 hr 10 min 
gave greater protection for greater thickness; and that the 
fire endurance of the particular column tested was 57 min . 


USCOMM-NBS-DC 



Temperature 





U.S. DEPARTMENT OF COMMERCE 
Frederick H. Mueller, Secretary 

NATIONAL BUREAU OF STANDARDS 
A. V. Astin, Director 

THE NATIONAL BUREAU OF STANDARDS 

The scope of activities of the National Bureau of Standards at its major laboratories in Washington, D.C., and 
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