ARCHIE'
PAPERS
OF
SHIP RESEARCH INSTITUTE
Performance of Fireproof Lifeboats of Reinforced Plastics
By
Osamu NAGATA and Kazuhiko OHNAGA
March 1980 Ship Research Institute
Tokyo, Japan
Technische Hogeschool
Delft
Papers of Ship Research Institute, No. 61 (March 1980)
PERFORMANCE OF FIREPROOF LIFEBOATS OF
REINFORCED PLASTICS FOR TANKERS*
By
Osamu NAGATA** and Kazuhiko OHNAGA"
INDEX
ABSTRACT
The International Convention for the Safety of Life at Sea encourages all the participants to undertake research work on tanker lifeboats which are capable of resisting fire when attached to davits, and of being safely lowered with their full complement and then cleared from the ship's side in conditions of fire on the surface of the water.
Much cooling water which flows on the outer surface of a boat will be able to protect the FRP lifeboat from fire. But it is very difficult to cover
Bibliotheek van de
Afddng Scheepsbov- en Sche?Tvaartkunde
Technisc,e ol, Delft
DOCUMENTATIE
DATUM1
Received on Nov. 19, 1979. Ship Equipment Division.
This paper is the translation of the report published in the Report of Ship Research Institute (Vol. 16, No. 3).
Abstract 1
1. Introduction 2
2. Heating Test of FRP Plate 4
2.1 Test Method 4
2.2 Test Results 7
3. Oil Fire Test of Model FRP Lifeboat 10
3.1 Test Method 10
3.1.1 Model FRP Lifeboat 10
3.1.2 Oil Fire Test Tank 11
3.1.3 Fire Test in Launching Process 12
3.1.4 Fire Test on Model Lifeboat 13
3.2 Test Results 14
3.2.1 Fire Test in Launching Process, T. No. I 14
3.2.2 Fire Test in Launching Process. T. No. II 19
3.2.3 Fire Test on Model Lifeboat, T. No. III 21
3.2.4 Fire Test on Model Lifeboat, T. No. IV 23
4. Tension Test of Heated FRP Test Pieces 25
5. Water Spray Test of Actual Tanker Lifeboat 29
6. Calculation of Heat Transmission 32
6.1 Calculation Formula 32
6.2 Case Study on Heating Test of FRP Plate 34
6.3 Case Study on Oil Fire Test of Model FRP Lifeboat 37 6.4 Case Study on Actual Lifeboat in Fire on the Sea Surface 39
7. Conclusion 41 Acknowledgement 42 References 43 ...-...-...
..,..._
...
...
..,...,
...
...
...
.,...all the outer surfaces of the boat with limited capacity of pump, when the boat is being lowered in the wind or running against the wind.
Therefore, it is necessary to investigate the extent of damage and effectiveness of heat insultation of the FRP lifeboat which is not
sub-stantially fireproof.
Two kinds of fire tests, tension tests of heated FRP plates, and water spray tests of actual tanker lifeboats were conducted as follows:
FRP plates of 750 x 990 (mm) which were the same materials as those of FRP tanker lifeboats were set vertically in front of a test furnace of about 500°C. And the plate was heated for twenty minutes while cooling water flowed on the surface of the plate.
Four runs of large scale oil fire tests were conducted using two kinds of half-size models of FRP tanker lifeboats.
Tension tests were conducted to know the extent of decrease of tensile strength affected by the heat addition to the FRP plate.
Water film thicknesses on the outer surface of shell were measured
for two kinds of actual tanker lifeboats.
The main results of the studies for the FRP fireproof lifeboat are sum-marized as follows:
The material of FRP tanker lifeboat, which is composed of self-extinguishing and fire-retardant additions, can resist an oil fire of 1000°C for about thirty seconds, without cooling water on the outer surface of shell
plate.
The water film of 0.6 mm in thickness on the outer surface of shell plate is necessary to protect the boat and crews inboard for five minutes in conditions of fire on the surface of the water.
In these conditions, the temperatures and heat fluxes of the boat will not exceed the following values.
Inner surface temperature of shell plate 150 ° C
Inboard air temperature 60°C
Heat flux into the outer surface of shell plate ....4500 Kcal/m°-h
Heat flux into the inboard air 300 Kcal/n.1241
1. INTRODUCTION
As everyone learned through the bitter experience with the collision of a LPG tanker "Yuyo Maru No. 10" of 44,000 G.T. with a cargo vessel
"Pacific Ares' of 11,000 G.T. in Tokyo Bay in Nov. 1974, marine casualty
of a tanker normally involves immeasurable risk of danger threatening the loss of number of human lives in the large scale oil fire on the sea surface in consequence of a massive oil spillage from the tanker.
In the International Convention for the Safety of Life at Sea, 1960, each contracting government was requested to undertake studies on life-boats for tankers. In accordance with such recommendations by the Con-vention, Ship Research Institute. Ministry of Transport launched its study project', on fireproof lifeboats in 1964, and essential design considerations, performance and operational criteria for tanker lifeboats were investigated through basic experiments (water spray test, air-tightness tests of access openings, air discharge tests from high-pressure vessels, operation tests of
i)
3
the engine with lean-oxygen suction air), and fireproof tests of a steel lifeboat.
Following the aforementioned experiments of a steel lifeboat, fireproof tests 2' on an FRP lifeboat were carried out by Japan Marine Machinery Development Association in 1968, and Ship Research Institute joined the
project by participating in temperature measuring.'' The results of the
tests have shown that even a lifeboat made of FRP material can serve as a fireproof lifeboat with satisfactory levels of fireproof characteristics and heat-resistant properties providing that the entire outer surface of the boat
is effectively cooled by sprayed water.
However, when FRP is used as the hull material of a fireproof lifeboat, effective cooling means must be established through careful studies as the FRP material itself is not essentially fireproof when compared with steel. Namely, in addition to the standstill upright condition of the FRPlifeboat, we must fully consider the safety features of the boat in the lowering process or in the running condition on the sea surface, including also such extra-ordinary cases that the cooling effect on the lifeboat by sprayed water is temporarily or locally missing by the heel of the boat or by being scattered into the air by wind. The full-scale fireproof tests of each prototype lifeboat in oil fire on the water surface may cause unjustifiable level of pollution and
unreasonable cost of experiment, if we insist on carrying-out of such large scale of fire tests. Accordingly, it has become necessary to predict the fire-resistant characteristics of the fireproof FRP lifeboat which have been the vital considerations in the evaluation of its safety features by obtaining the relationship between the flow rate of sprayed water on the outer surface of the lifeboat and temperature of the boat itself, the temperature of the
inboard air and also the heat flux into the lifeboat.
In this study the following items were investigated and verified : The minimum rate of sprayed water capable of maintaining an un-broken water film on a vertically held FRP plate subjected to heating in a small heating furnace and the burning condition of the FRP plate were examined.
Oil fire tests were carried out using models of FRP lifeboat under the test condition closely resembled to an actual case of FRP lifeboat in oil fire on the sea surface.
On the basis of the measured results obtained through tests (1) and
(2) above, the heat transmission characteristics of the FRP plate were analyzed, and the values of coefficients necessary for the calcula-tion of fire-resistant performance of actual FRP lifeboat were de-termined.
After completion of fire tests (1) and (2), test pieces were taken from the vertically-held FRP plates and the models of FRP lifeboat, and the depth of burn damage and the residual strength of the test pieces after the heating were investigated.
THERMAL CONDUCTIVITY 115 0, 0 THERMAL CDFFUSIvITy T, PIECE MARK SPECIFIC .NE AT 100 .1 TEMP. e0 4.5
Fig. 1., Property values of FRP plate.
111
0
4,0
Water spray tests were carried out on actual FRP lifeboats and the distributions of water film thickness on the outer surface of the life-boat were measured.
By using the results of (3) and (5), proposals were made for predict-ing the fire-resistant characteristics and the thermal insulation per formance of an actual FRP fireproof lifeboat.
2. HEATING TEST OF FRP PLATE
The thermal conductivity and the thermal diffusivity of FRP material are approximately 1/200 and 1/100 of that of steel respectively. However, its smoke point is in the neighbourhood of 230°C, and its ignition point is approximately 400°C. In view of these physical properties inherent with FRP material, it is indispensable to provide means to cool its surface by water sprinkling or the like when such material is used as the hull material of the fireproof lifeboat.
The breakdown of water film, the burning conditions of the plate and
the temperature rise were investigated when vertically held FRP plates covered with falling water film at various flow rates were subjected to heating.
2.1 Test Method
The FRP material used for fireproof lifeboats is mixed with 'approxi-mately 10 parts of antimony trioxide and paraffin chloride to 100 parts of polyester resins for improving its nonflammability and self-extinguishing
properties, and is formed to a thickness of 6 to 8(mm) with a specific
gravity of 1.5 to 1.6 being filled with 28 to 35( ) of glass fibre. The
chem-ical compositions and thickness of FRP plates used in the tests were the
same as the shell plates employed in the fireproof FRP lifeboatsbuilt in the
domestic shipyards. As shown in Fig. I, the thermal properties such as
specific heat and thermal conductivity vary with temperature, but the
dif-ferences between specimen B (formed to a thickness of approximately
7 mm by the hand lay-up method with 35% of glass fibre content under the
0,5
'Z02 8
all
Fig. 2. Heating and water supplying apparatus of FRP test plate.
right-hand side walls, 30 units on the front wall, and 6 units on the floor
for ensuring uniform temperature distribution within it. The FRP test plate of 0.75 m in height and 1 m in width was held on an open vertical plane in front of the furnace. The water overflowing from the upper water tank goes down 0.15 m along the vertical outer surface of the steel water tank and runs down 0.75 m along the vertically held FRP test plate, and then
it is drained outside.
In order that the heating surface of the FRP
test plate is covered with uniform thickness of falling water film, careful consideration was given in the finish of the upper edge of the vertical steel plate of the water tank and the seam between the steel plate and FRP test
plate. On the non-heated side of the FRP plate,a model box of 0.4 m in depth
lined with thermal insulation of glass wool was provided for accumulating
5
glass fibre lamination of 450M x 2+600M x 3+600R +600M) and specimen C (formed to a thickness of 8 mm by the sprayed-up method with 28% of glass fibre content) were not significant.
An external view of the heating and water supplying apparatus is
shown in Photo 1. The inside dimension of test heating furnace is 1.4 m in height, 1 m in width and 1 m in depth, and the test furnace is provided, as shown in Fig. 2, with propane gas burners-26 units each on the left and
Photo 1. Heating and water supplying apparatus.
MEASURING POINTS OF TEMPERATURE NO. OF GAS BURNERS FIRE
INNER SURFACE OF
A9 - A19
FURNACE A20 -A22
FRONT SIDES 30 2612 OUTER SURFACE OF INNER SURFACE OF
FOP PLATE AO -AR
FRP PLATE BO 08 FLOOR 6 INNER AIR WATER BB -BIN820 - 023 AT000P4ERE A23
-the heat transferred from -the FRP plate.
Exposed Chromel-Alumel thermocouples were used for the temperature measurements of the following points:
11 points each for the fire temperatures within the furnace and for inner air temperatures inside the model box
9 points each for the temperatures on the inner and outer surfaces
of the test plate
1 point each for the atmospheric and supply water temperatures
3 points for the drain water temperatures
3 points for the temperatures on the inner surfaces of the furnace
The thermocouple wires of 1 mm o were used for measuring high
tem-peratures of fire and the inner surfaces of the furnace, whereas
thermo-couples of 0.3 mm o were used for the rest of measuring points, and all measured temperatures, 48 points in total, were continuously printed out by two digital temperature indicators.
Thickness 3 of the water film flowing down along a smooth vertical
plane surface, in case of laminar flow, can be expressed by Nusselt's4) theorem (1) , and when Re>400, it is expressed by Brauer'sp) experimental equation (2) as follows:,
when Re <400
k g
y3Reo ( 1 )when Re >400,
0 .302(-=`'2 )
-Re"'
( 2 )where acceleration of gravity
v : kinematic viscosity
Q: volume flow rate per unit width
Re: Reynolds number of liquid film (= Q1)
For water filth thickness measurements, the water electric resistance. ,servo-meter with an up-and-down needle was used, and water film thickness values changing irregularly with time were analyzed by the signal processor and probability density of the thickness was determined asshown in Fig. 3. The probability density curves are approximately analogous to the form of normal distribution. As the water overflowing from the upper water tank
runs downward, it becomes faster and waves, and the mean value of water
film thickness with time decreases,, but the fluctuation of thickness increases. The relationship between the mean value of falling water film thickness with time and volume flow rate per unit width obtained from Fig. 3 is shown in Fig. 4. Although the thickness of water film on the outer surface of steel plate (80 mm from the top of the plate> is larger than that obtained from
CI MEAN THICKNESS OF WATER (FILM '..'STANDARD DEVIATION
.5 1.0 .
THICKNESS OF FALLING WATER FILM CM141 Fig. 3. Probabilty density of water
film thickness:,
LT_ UPPER PARTS
(ON THE STEEL PLATE)
UPPER PARTS
AMIDDLE PARTS./ (ON THE IFRP PLATER LOWER PARTS U. Ii Re (04) 0 300 400 500 10 20 30
FLOW RATE (L/MIN.M)
Fig.. 4., Thickness of falling water -film.,
RRAAR (Re) ool
40
7
equations (1) and (2), the water film thickness measured on an. FRP plate (over 500 mm from the top of the plate) is in close agreement with the value calculated from the equations.
The water film thickness under the volume flow rate per unit width of Q=25 //min.m with a water temperature of 20°C is approximately 0.5 mm, When the value of Q is less than 10 //min.m, it becomes difficult to obtain uniform water film thickness on the outer surface of the plate:
After the temperature rise in the furnace nearly stopped, the vertical
FRP plate on a tray covered with falling water film was inserted at the
open plane of the furnace, and the plate was heated for approximately 20 minutes. Since no differences were noted among the fire temperatures at the deep position of the furnace (A19 in Fig. 2), in the center of the furnace.
(A18) and in the neighbourhood of the FRP plate (A13), the mean tem-perature of the combustion gas measured at 9 points in the neighbourhood
of the FRP plate (A9A17) was regarded as the mean temperature of
fire in the furnace.
The average temperature of fire in the furnace is as shown in Fig. 5, and it reached 520±40(°C) in 5 minutes, and 550±30(°C) in 1.0 minutes.
The volume flow rates per unit width Q used in this test were 0, 10, 17.5, 25 and 40 (//min.m).. An additional test under the average fire temperature
of 400°C in 5 minutes,. 420C in 10 minutes was carried out for the case of Q=0.
2.2 Test Results
The results of tests on non-water-cooled test plate C were shown in Figs. 6 and 7.
Average temperatures of the outer and inner surface of the plate and the inner air temperature of the box were plotted when the average tem-peratures of fire in 5 minutes were 400°C in Fig. 6. When the temperature.
\
L /MIN HEIGHT 0.41/ (MM) 1 20 LOWER .50 .07 20 UPPER .56 .02 40 LOWER .61 It 40 UPPER .79 .03I .1720 (LAMINAR) 6 2 C 600.011 11.2.1 '2;!_ il 0 Lc" 7ob 600 sob
40
PO, a: 2 300rrEMP. 'OF ATMOSPHERE; TA =16..0°C )
;
8 OUTER SURFACE TEMP. OF FRP 'PLATE Win a INNER SURFACE TEMP. OF FRP PLATE01,NN.ER A l.R TEMP. a: UI2 II_ 00, 1 2 4 6, 113 142 14 16 1'8 20 TIME- (MIN.) Fig. 6. Average temp. of FRP plate
(No cooling, C2).
FLOW RATE MARK T.NO kL/MiN1
C3 0 C2 0 '200 A C2 10 C3 17.5 B2 25 C3 40 10 12 TIME (MIN.)'
Fig. E. Average temp. of fire in the fireplace.
0 1 0 0 LU go I 11-1 0 I( TA 7.0'C /
iiOUTER SURFACE TEMP. olINNER SURFACE TEMP. oi1NNER AIR TEMP.,
18 NO 112 14 1 6 .18 20
TIME-(M1N.)' Fig. 7. Average temp. of FRP plate
(No cooling, C3).
of fire was lower than the flash point of FRP' material, a large volume of thick black smoke was emitted from all the heating surface of the test plate due to combustion of gel coat resins, but no burning flame of any signifi-cance from the surface of the test plate was observed, and the temperature
rises on the outer and inner surfaces of the test plate were 140°C and 40°C respectively in 5 minutes, and 200°C and 100°C respectively in 10 minutes. When the temperature of fire was approximately 500°C, however, flames were generated on all the heating surface of the test plate in 6' minutes and the plate temperature rose sharply afterwards as shown in Fig. 7. No disintegration of glass fibre was noted in either case, and no significant change of the plate in shape and appearance was observed either. The results of tests are shown in Figs. 8 to 11, when the heating surface of the FRP plate exposed to fire at the temperature of approximately 500°C
goo Average temp. of A9A17 in Fl9.2
0
0
WO O('1 111 1-0 TA 8 0 °C ...
...
...
2 4 6 8 10 12 14 16 18 20 TIME -C MIN.)Fig. 10. Average temp. of FRP plate
(25 //min. m, B2)
(TA 6.0 °C )
2 4 6 8 10 12 14 16 8 2.0
TIME - ( MIN.)
Fig. 9. Average temp. of FRP plate
(17.5 //min. m, C3). ( T. 5. 5 't )
PV=gggggg
I I I I I 0 2 4 6 8 10 1.2 14' 1 T6 1.6 20 TIME- (MIN.)Fig. 11. Average temp. of FRP plate
(40 //min. m, C3).
9
is cooled by falling water at the volume flow rate per unit width of 10-40 (//min.m).
The entire surface of the FRP plate at the volume flow rate per unit width of 10-17.5 (// min.m) is uniformly covered with water film when no heating is added, but once the plate is placed in the furnace, the water film immediately starts to breakdown with the occurrence of boiling and evapora-tion of water. Thus the surface of the plate is burnt and roughened as shown in Photo 2. The roughened surface encourages disturbance of water flow
and then acceleration of water evaporation. In these cases the heating surface of the FRP plate receives radiation energy either penetrating
through the thin water film or directly through the broken area of water film. Therefore, the surface temperature of the FRP plate is higher than that of the drain water as shown in Figs. 8 and 9. When the volume flow rate per unit width is in a range from 25 to 40 (/ min.m), the water film formed on the surface of the FRP plate is not broken even when it is placed
( TA 7.0 °C ) O OUTER SURFACE TEMP. AO-08
DINNER SURFACE TEMP. BO 138
o INNER AIR TEMP. 89-8I7
A SUPPLY WATER TEMP. 820
Lu +DRAIN WATER TEMP. B21 B23
0 0
-;4 113 lb 12 4 16 18 20
TIME- (MIN.) Fig. 8. Average temp. of FRP plate
(10 //min. m, C2).
-
Photo 2. FRP plate (10 //min. m, C2).
in the furnace, where most of the radiation energy is absorbed by the water
film and it is discharged together with the drain water. Therefore the
temperature of the surface of the FRP plate is lower than that of the drain water as shown in Figs. 10 and 11. And no generation of smoke or occur-rence of burning from the plate is observed. The critical volume flow rate per unit width capable of cooling the outer surface of the vertically held FRP plate in the small heating furnace effectively has been proved to be approximately 25 //min.m.
3. OIL FIRE TEST OF MODEL FRP LIFEBOAT
In order to verify that the critical volume flow rate per unit width determined through the heating test of FRP plate in a small heating furnace is also effective for an actual FRP lifeboat, model FRP lifeboats covered
with cooling water at a critical volume flow rate per unit width of 25
//min.m were placed amid an oil fire, and then the burnt condition of the boat, and temperature rises in the boat hull and inboard air were examined. Since it was predicted that water spray on the lifeboat would possibly be disturbed by the heel or trim of the lifeboat in lowering or running condi-tion, or by being scattered into the air by wind, fire tests were also carried out in such extraordinary conditions of spray.
3.1 Test Method
3.1.1 Model FRP Lifeboat
The models of FRP lifeboat used in the test are shown in Fig. 12. The model lifeboats have simplified figures of 1/2 scale of an actual lifeboat. The models of the midship body and aft body were separately prepared to know the sprinkling effects on the sides and bottom shell plate of different inclinations. Each model lifeboat is 2 m in length, 1.4 m in breadth and
1 m in depth. The FRP plate is formed to a thickness of approximately
7.5 mm by hand-lay-up method with 28% of glass fibre content with the lamination of G.C.+600M x 5+450M. The gunwale of the model lifeboat is
End 01 rr Stiff 6 0400 .ro Covered .06 450.2 N_02 (tor Po sooge (Midship F o're _N_0.4 (f or_LI/J_ -*.(5/0_0 Water ton. Eg, Pp:5 Port PL u 400 co NS2..4Cf or 1,111/01Tegs, Sannh1.4_114act____ 2200 If- et)
Ottpump. o_oc meSor g
.-O o -C J. I o0iI I 4 .0 ',. En
iyili
. aemraa ti 11111M11111.!!MiMit L3490J L Fig. 13.Fig. 12. Models of life boat.
rounded for ensuring undisturbed uniform flow of falling water along the surface of the boat. However, such rounded corner was intentionally omit-ted at fore and aft end corners of the deck to check the cooling effect of the sprinkling water.
3.1.2 Oil Fire Test Tank
The arrangement for fire test is shown in Fig. 13. The test tank is
S torb
00
22
om.eter NO.L
, (for T.NO I-01)
(or Ao0o0 _4._L0000_ . NO.I(for IV) 40, 52500 3500. 2000.0 Arrangement for fire test.
M_04_6 Trii-Ast ,urfocetemp. It 5,00,1 IflBEmomete R om e ss 0 0 t?.; _250Q 11
made of steel plate with dimensions of 15 m in length, 11.4 m in width and 0.9 m in water level so that the distance between the model lifeboat and tank wall can be secured at least 5 meters. The boat deck and launching device are provided at the middle of the longer side of the water tank so as to receive sufficient amount of radiation energy. Four poles are vertically held at four locations of the tank for measuring fire temperature at elevations of
ip.o. I,. i_.1_ -. 'I° i , so.ss , YBP.Oil POO 2000 0 IA.OF PIPE 050 11. 050 50 0.025
OUTER SURFACE TEMP.
I NNER SURFACE TEMP.
NNER AIR TEMP
,6.01
;
a 0
0.5, 1.5, and 2.5 (m) above water line respectively by Chromel-Alumel
thermocouples with SUS protection tube of 3.2 mm..
3.1.3 Fire Test in Launching Process
When a fireproof lifeboat launches into the sea surface enveloped in flames, two types of water supplying system may be considered ; i.e., the one is a system where water is pumped from the mother ship and supplied
through the connecting hose to the sprinkler pipe of the lifeboat, and the other is a system where water from the ship is directly sprayed to the boat. Although the former system has such advantage that the almost entire outer surface of the lifeboat can be covered with sprayed water, it inevitably in-volves defects such as complicated handling for connecting the mother ship to the lifeboat by the hose. While on the other side, the latter system is
featured by its simple design requirements and reliable operational per-formance in an emergency. Therefore this system is often used in practical
applications. However, it also can not be free from such disadvantage
that the water sprinkled from the nozzles at the height of the boat deck of the ship will be disturbed by wind blow..
In the test No. 1 of the above latter system, the midship body of the model lifeboat was suspended by the davit at a height of 1 meter above the water level of the tank, and water was sprayed upon the deck of the model
lifeboat from the sprinkler head provided at the top of the cradle at the
height of approximately 7 meters above the water level. The boat deck and launching device were covered with sprayed water from the drencher head provided in the vicinity of the sprinkler head. The flow rate of the sprinkler head at a pressure of 1 kg/cm2 was 80 //min.., and the effective coverage
diameter of sprinkled area on the water surface was approximately 10
meters when there was no wind. The flow rate of the drencher head wag. 80 //min., the angle of divergence was 90°, and the reach was approximately 5 meters, when sprinkling was carried out on a horizontal plane at a pres-sure of 1 kg/cm2. The used fuel was 72 liters of gasoline for ignition and 1,280 liters of heavy oil of class A. The Chromel-Alumel thermocouples with SUS, protection tube of 1 mm o were arranged at 6 points each for temperature measurements on the outer and inner surfaces of shell plate,. the inboard air, the surface of steel members on deck, and ambient air tem-perature in the vicinity of the deck. These 30 points together with the afore-mentioned 12 points of fire temperature were subjected to. automatic
temperature measurements by two units of digital temperature recorders.. The points of temperature measurements are shown in Figs. 12 and 13.
In the test No. II, no water was applied to the model lifeboat assuming a failure in the sprinkler system, and the same amount of fuel as in the test No. I was used. It must be noted that the model lifeboat used in the test
No. I is again subjected to intense oil fire without cooling, although the
13
break-down of the model.
3.1.4 Fire Test on Model Lifeboat
In the fire test on the model lifeboat, the midship and aft body were supported in the centre of the test tank where twice the quantity of heavy oil as that used in the fire test in launching process was burnt. For estimat-ing the amount of heat transmission to the lifeboat and for examinestimat-ing the cooling effect of the drencher heads for midship bottom, the model lifeboats were supported on a frame levelled at an elevation of 1 meter above the water surface so that the bottoms were also exposed to the fire during the
test. The arrangement of water sprinkler pipe is shown in Fig. 12. The
spout holes of 3 mm in diameter are arranged in three rows in the center sprinkler pipe "A" of 50 mm in diameter. The pitches of the holes in the
center row "c" with the direction of spouting vertically downwards are 100 mm, and the pitches of the hole in both side rows "a" with the direction of spouting at 45 - are 50 mm. The spout holes "b" of 3 mm in diameter with the pitch of 50 mm are arranged in a single row in the end sprinkler pipes "B" with the direction of spouting obliquely down towards the end plates. The fire test No. III was carried out at the critical volume flow rate per unit width of 25 //min.m, confirmed by the heating test of the FRP plate. And the flow rate from the sprinkler pipe right above the model lifeboat is 195 //min. for the midship body and the aft body each. One drencher head with the angle of divergence of 180° in the horizontal direction was addi-tionally arranged below the bottom on each side of the midship model to cover the bottom surface with sprayed water at the flow rate of 60 //min. under the pressure of 1 kg/cm2. Accordingly, the total rates of sprayed water were 315 /min. for the midship body, 195 //min. for the aft body ; thus making the total to 510 //min.
When water mentioned above was sprinkled, the maximum
pres-sure in the sprinkler pipe was 0.3 kg/cm2 and the thickness of water film was approximately 1.7 mm on the deck, 0.6-1.3 (mm) on the side plates, and 0.5-0.8 (mm) on the end plates. For the lifting eye-bolts of the model lifeboat, the sprinkler pipe had to be installed at the higher position of the
model than in the case of an actual lifeboat, therefore the water stream directed to the end plates was affected by wind blow, and thus the condition of water sprinkled on these plates was not necessarily satisfactory.
In the test No. IV, the flow rate from the sprinkler pipe was decreased
to 1/3 of that in the test No. III and the drencher heads were not used.
Namely, the flow rates of sprayed water for the midship body and the aft body in this test were 65 /, min. for each ; thus making the total to 130 //min. The maximum pressure in the sprinkler pipe was 0.15 kg cm' and the thick-ness of water film was 1.1-1.5 (mm) on the deck, 0.5-0.7 (mm) on the side plates, and 0.4-0.7 (mm) on the end plates. When there was no wind, the entire outer surface of the model lifeboat was barely covered except for the bottom plate of midship model around the centre line.
3.2 Test Results
The summary of test result from the test No. I to No. IV is as given in Table 1.
3.2.1 Fire Test in Launching Process, T. No. I
(cooling by the sprinkler on the davit ; the model lifeboat suspended above water)
In one minute after ignition, the fire spread all over the entire area of the water surface with peaks marked in a period from 1 minute 30 seconds to 3 minutes 30 seconds when the model lifeboat was totally enveloped in flames as shown in Photo 3, and the model lifeboat was completely out of sight. The temperatures of the fire were as shown in Figs. 14 and 15, and
reached 500-1,100(°C) except for those areas affected by the splash of sprinkled water. In five minutes after the ignition, the area of the sea surface enveloped in flames decreased to approximately 1/5 of the total area of the tank, and the fire went out of the model lifeboat and extinguished
-
-Photo ,a. Fire of T. No. I (2 min. after ignition)..
2 3 4 5 6, 7 8 9 10 Li
TIME (MIN.)
Fig, 14. Temp. of fire (T. No. I, fore
and aft). ?i000 0. '11.1 I- 800 BOO 400' 200 6 7 8 9 I0 II TIMEcroiN.%
Fig. 15. Temp. of fire (T. No. I, sides).
0 Ft) o FM A FL AU AM AL 1200 0 0 PM PL SU SM SL 1200 c,71000 600 400 200 2 3 4 5
Table 1,
Test results of fire test
Type of test
rue test in lat nchjng process,
,
Fire test on Model lifeboat
Test No, T, Not I
- -
--T. No, II- - - -
--T. No. HI = = T. No. IV 1 Test date 9:20 aim Nov. 16, '77 1:20 p.m, NoV, 16, '77 9:20 ann. Nov. 18, 1.77 ', 1:20 p.m. Nov. 18, '77 __ -en 0 O.) ;--, 0- - Atmospheric tempi and humidity
7.5°C, 87% 11.5°C, 78%
-
-
--17C, 73% 12°C; 78% Water -temp, '6.5°C , 19°C 15°C 19°CWind direction and velocity
NNE ,0.8-1.0 (m/s) ____ ____ NNW 0,4-1.2 (m/s) NW I. 2--4.2 (in/s): NW 1.8-4. 2 (m/s) -,-> 76 g -0 4 Type
Mid ship body
The model boat used in T. No. I
Midship body and aft body The model boats used in T. No, III
Installed position
End of the water tank at a height 1 ni above W.L.
End of the water tank with a draft of 150 mm
Middle of the water tank at a height 1 in above W.L. Middle of the water tank at a height lm above W.L.
Rate of Sprinkling (//min.)
Boat d ck \ , w , Boat de avit) " Boat deck \ 60, Boat davit)
Midship body: Deck & sides
195
Bottom PL
120
Midship body: Deck & sides 65-°0 Bottom PL
0 1 Model lifeboat
-'Model lifeboat Aft body 195 Aft body ..-1 a) 0 44
Kin d and amount
Heavy oil of class A
1280 /
Heavy oil of class A
1280 /
Heavy oil of elass A
2560 1
Heavy oil of Class A
2560 1
Thickness abave water
7.5 min 7.5 min 15 min 15 inni 0 65,0
Test No.
Type of test Deck plate Fire Outer surface of shell plate Inner surface of shell plate Inboard air
T. No. I
Soot found on four corners, but no trace of burn on gel coat. Gel coat cabonized Two glass fibre layers in average found carbonized, and secondary joints found locally separated. Gel coat found carbonized allover.
Table 1.
(Continued)
Secondary joints all
No appreciable
carbonized and
change noted.
separated from the body, but no damage to packing. Two to three layers in average found carbonized allover. Two to three layers in average found carbonized, and secondary joints found locally separated. As submerged below water, no progress than that noted in T. No. I observed.
do.
Gel coat found locally carbonized.
do.
Gel coat and one layer found locally carbonized. Gel coat found locally carbonized. Gel coat found locally carbonized.
do.
Midship body
Aft body
Gel coat locally carbonized. One layer aft found carbonized. Gel coat found sub- stantially carbonized. One to two layers in average found carbonized and locally separated. Two layers found carbonized. Two to four layers found carbonized, and secondary joints separated from the body. Two layers found carbonized. Three to four layers found carbonized. Midship body
Aft body
Midship body Aft body Midship body Aft body Midship body Aft body Midship body Aft body
'Note]
These low indications were the fire temperatures above the fore part of the midship body affected by the north- westerly wind.
750-1090 *440-1210 *340-1050 .360-1200 50 560 670 800 25-450 42-120 75-650 460,-420 40 150 170 210 20 41 27 38 39 80 160-220
45 70
130 146 30 33 18 28 50 60 85-165Fire test in launching process
Fire test on model lifeboat
T. No. II
T. No. III
T. No. IV
Side plates Fore and aft end plates Bottom plate
1 -
-250 200 II-N.1 15 50 10
2 34 5 67 8
9 10 II TIME 1I)Fig. 16. Steel surface temp. around the
boat deck (T. No. I).
oS)) 52 S3 S4 55 S6 0 ) 2 3 4 5 6 7 8 9 10 I% TIME (MIN-)
Fig: 18. Temp. of outer surface of shell
plate (T. No.
200
0 I 2 3 4 5 6 T 8 9 10 I,II
TIME (MIN.)
Fig. 17. Air temp. around the boat
deck (T. No. I).
2 3 4 5 6 7 8 9 10 II
TIME (MIN.)
surface of
Fig. 19. Temp. of inner
shell plate (T., No. I).
17 naturally in eight minutes. During this period, the flame stood upright to a height over 20 meters. The measured temperatures of the surface of the steel members and air around the boat deck are shown in Figs. 16 and 17. The temperatures of outer surface, inner surface, and inside air of the model lifeboat are as shown in Figs. 18, 19 and 20. The sprayed water was
dispersed by the wind induced by the fire, and the effective flow rates of
spray, in terms of the amounts of water directly reaching the boat deck
and the deck of the model lifeboat, were approximately 10 //min.m2 and //min.m2 respectively.. In this condition the temperatures of the surface
200 100 250 150 100 50 0 I '7 I). 7 50 00 50
5 C.
2 3 4' 5. 6' 7 8 9 ND
TIME (Mill.)
Fig. 20. Temp. of inboard air (T. No.
of the steel Members and air around the boat deck, except for the areas
directly above the fire (Al, A4, Si and S4 in Fig. 13), were 40°C or less, and the strength of the boat deck and functions of the launching gears were not affected by the fire. The burnt condition of the model lifeboat is shown in Photo 4 in which we recognized that the deck remains almost intact, but
Photo 4. Model after T. No. I.
the side plate, bottom plate, and fore and aft end plate are damaged. Such can be attributed to the specific considerations in which the corners con-necting the deck with side plates were rounded to facilitate smooth flow-ing down of the water from the deck to the sides. On the contrary as the corners which connected the deck with end plates were intentionally left un-rounded, the flow of the water on the end plates were in worse condition. The materials of fore and aft end plates which were not effectively cooled
by the Water were found carbonized in two glass fibre layers, and the
secondary joints were found separated in part. The materials of bottom
and side shell plate, where the cooling effects of the water flow were less, were found carbonized in one layer locally, and the gel coat was almost
entirely burnt all over. However, the boat deck was found nearly intact. The flow rate of 'effective sprayed water as low as approximately 10 //min.m2 proved to be effective to protect the model tolerable for a few minutes.. F.
1'
Pr.11. 100 I).1,200 0'1000 2 1.-"- 800 600 .4 200
2 34 5
6 7 6 9 10 II TIME (MM.)Fig. 21. Temp. of fire (T. No. II, fore
,arid aft). cr, FUI FM FL Au' AM AL 120 i 000 800 600 400 200"
Photo 5. Model after T. No. II.
1( 2 3 4 5 6 7 8 9 10 II
TIME (MIN,) Fig. 22. 'Temp,. of fire (T. No.. II,. sides).
19 The end plates and the bottom plate of the model lifeboat were found burnt locally, and their outer and inner surface temperatures reached 560°C and 150°C respectively. The temperature rise of the inboard air reached
°C)' from the initial temperature at maximum.
3.2.2 Fire Test in Launching Process, T. No. II
(no cooling ; the model lifeboat floating on the water)
In two minutes after ignition, the fire spread all over the entire area of the water surface with peaks marked in a period from 2 minutes 30 seconds to 4 minutes 30 seconds. The temperatures of the fire are as shown in Figs. 21 and 22. Although the temperatures at FU, FM and FL on the north of
the water shown in Fig. 13 were relatively low due to the NNW wind,
the other temperatures reached 600-1200 ( °C).. In six minutes after the ignition, the area of the water enveloped in flames decreased to approxi-mately 1/5 of the total area of the tank and the fire went out of the model lifeboat, and in six minutes SO seconds the fire extinguished naturally. As
I
35-60 (
shown in Photo 5, the model lifeboat without cooling was found carbonized allover in two to three layers with two lines of fine cracks running on the aft end plate. However, no significant changes in shape and color inside the boat were noticed. After completion of the Test No. I, two glass fibre layers of the middle part of the aft end plate had been cut off for observation. As a result, the burn damage on this part was worsened further and only one to two layers were left undamaged after the test. From these experiments, it
may be found that even the detached outer layer of carbonizd resins and fibre serves to protect the inner layers to a considerable extent from being affected by heat. The secondary joints between the deck and the end plates were found seriously carbonized and almost separated from the boat body.
The temperatures of the outer and inner surfaces of the shell and the Inboard air are shown in Figs. 23, 24 and 25. The outer layers of the life boat were 'completely burnt, and the temperature rise of the inner surface and inboard air reached 160-200(°C) and 120-135 (°C) respectively from the initial temperatures.
5 6 7 8 9 10 )1 0 I; :2
34
345 6 78 9
1011TIME (MIN.) TIME (MIN.).
Fig. 23. Temp. of outer surface of Fig. 24_ Temp. of inner surface of
shelf plate (r. No_ IT). shell plate (y., No. II).
150 oa M1 SP o: F WO 0' 50 CZ; .6:200 LUI II 50: )100 50 TP 13 SP A SS, F ,0 I 2 3 4 5. 6 8 9 10 II TIME (MIN.)
Fig. 25.. Temp. of inboand air (T. No. II).
2
1 °I 000: o: 600 400 0 r--o FM A FL AU Is AM AL 01i000 0. 800j 400 2 00 ,600 2 3
4 56 7
8 9 10 1.11 TIME (MIN.)Fig: 26. Temp. of fire (T. No. III, fore, Fig. 27., Temp. of .fire. (T. No. III,
and aft). sides).
Photo 6. Model after T. No. III.
11 2 3 4 5 6 7 8 9 10 II TIME (WM) 13 PM PL Sul SM SL. 21
3.2.3 Fire Test on Model Lifeboat, T. No. III
(the model lifeboat supported in the centre of the tank ; the flow rate of cooling water 510 //min.)
In one minute after ignition, the fire spread allover the entire area of the water surface with peaks marked in a period from two minutes to five, minutes 30 seconds. The temperatures of the fire are shown in Figs. 26 and
27. Although the temperature at FU on the north of the water was relatively' lower due to the NW wind,, the other temperatures reached 500-1050 ( °C).
In seven minutes the area of water enveloped in flames decreased to 1/5 of the total area of the water, and the fire went out of the model lifeboat, but it took 16 minutes before it was extinguished naturally. This delayed
ex-tinguishing was caused by the repeated combustion of fuel in varying
intensity as the fuel was drifted to the south end of the water due to north-westerly wind of 1.2 to 4.2 (m/s)...
The burnt condition of the model lifeboat after the test is shown in
Photo 6. The fore and aft end plates and thecorners were found carbonized
800
on the gel coat due to poor water flow condition caused by the wind, but the rest of the areas were found intact.
In the case of actual lifeboat, the corners connecting the deck with the end plates must be rounded, and the sprinkler pipe should be installed as closer to the lifeboat body as possible.
The temperatures of the outer and inner surfaces of the shell and in-board air are as shown in Figs. 28 to 33. The highest values of temperature rise were 10-30 ( -C) at the inner surface of the shell and 5-20 ( °C) at the
o 400-450. 350- 300- 250- 200-BO 50 TP a SP . SS BP BS F ,.;04.1:-0 I 2 3 4 5 6 8 9 IO 11 TIME (MIN.)
Fig. 28. Temp. of outer surface of
shell plate (T. No. III, midship).
0 2 3 5 6 7 8 9 10 II
TIME (MIN)
Fig. 30. Temp. of inner surface of
shell plate (T. No. III, midship).
1-100
50
2 3 4 5 6 7 8 9 10 II
TIME (MIN)
Fig. 29. Temp. of outer surface of
shell plate (T. No. III, aft body).
0 I 2 3 4 5 6 7 8 9 10 II
TIME (MIN)
Fig. 31. Temp. of inner surface of
shell plate (T. No. III, aft body).
ALI 2 0 a: 01 ; 4 TIME (MIN.)
Fig. 32. Temp. of inboard air (T. No
III, midships). I200.1 :e 11)09r ALI 1- 800 600 4"00 200 0 01 M SP SS F FU' FM FL AU AM AL
Fig. 34. Temp. of fire-(T.. No. IV, fore
and, aft).
inboard air, and the arrangement of sprinkler piping and drencher heads at the bottom has been proved to be satisfactory.
3.2.4 Fire Test on Model Lifeboat, T. No. IV
(the model lifeboat supported in the centre of the tank; the flow rate of cooling water 130 //min_.)
In one minute after ignition, the fire spread allover the entire area of the water surface with peaks marked in a period, from one minute 30 seconds to five minutes. The temperatures of the fire are as shown in Figs_ 34 and 35. Although the temperatures at FU, FM and FL on the north of the water were relatively lower due to the NW wind, the other temperatures reached
600-1200 ( °C). In seven minutes after the ignition, the water area
enve-loped in flames decreased to 1/5 of the total area of the tank, and the fire went out of the model. In this test too, the fuel on the water surface was
drifted to the south end of the water due to the NW wind of 1.8 to 4.2(m/s),.
1110001 0:
II 2 3 4 5 6 7 8 9 10' III
TIME (MIN.)
Fig. 33. Temp. , of -inboard air (T. No.
III, aft body).
1200 800 600. 400' 20a, 10 low A PL SU SMI SL 0 I 2 3 4 5 6 7 le 9 10 II TIME (M
Fig. 35.. 'Temp. of fire T. No IV,
sides), 0 2 5 6 7 8 9 2 3 4 5 6 7 8 9 0 II TIME . 23
Therefore, the aft body on the lee side was enveloped in flames for five minutes 30 seconds and was subjected to far more severe thermal conditions
than that of the midship body. During this test, the power supply of
the sprinkler pump failed in about two minutes after ignition, and all
the sprinkling was cut off after that time. As the result, the extent of the damage to the models was, as shown in Photo 7, as serious as that in the
Photo 7. Model after T. No. IV.
test No. II of the fire test on model lifeboat without water cooling. In partic-ular, the aft body was found carbonizedone layer on the deck, one to two
layers on the side shell plate, two to four layers on the fore and aft end
platesand the secondary joint above the port side stiffener within the boat was found to be separated.
The temperatures of the outer and inner surfaces of the shell and in-board air are as shown in Figs. 36 to 41.
IC00 600 400 200 0 L 2 3 4 5 6 7 8 9 10 II TIME (MIN.)
Fig. 37. Temp. of outer surface of shell plate (T. No. IV, aft body). 2 3 4 5 6 7 8 9 tO II
TIME (MIN)
Fig. 36. Temp. of outer surface of
shell plate (T. No. IV, midship).
I
1:200 150 100 50 (-2 150 a: Lu z 100 50 0 I 2 3 4 5 6 7 8 9 10 TIME (MIN)
Fig. 40. Temp. of inboard air (T. No.
IV, midship).
2 3 4 5 6 7 8 9 10 II
TIME (MIN.)
Fig. 39. Temp. of inner surface of
shell plate (T. No. IV, aft body).
0 I 2 3 4 5 6 7 8 9 10
TIME (MIN)
Fig. 41. Temp. of inboard air (T. No.
IV, aft body).
4. TENSION TEST OF HEATED FRP TEST PIECES
When a lifeboat has escaped from the sea surface enveloped in flames, it may locally be damaged by burning with insufficient residual strength and possibly unfit for further service at sea. In order to clarify this point,
ten-sion tests were carried out on the test pieces used in the heating test in Section 2 and those subjected to oil fire tests in Section 3 in accordance with the requirements specified in JIS K6911.
The tension test results for heated test pieces are shown in Table 2. Photos 8 to 11 show the fractured condition of the test pieces subjected
to the tension test. Photo 8 shows the test pieces taken from the heated FRP plate cooled by falling water at a rate of 10 / /min.m in the heat-ing test of FRP plate described in Section 2, and Photos 9 to 11 show
the test pieces taken from the model lifeboat after the oil fire tests. The 25
2 3 4 5 6 7 8 9 10 II
TIME (MIN.)
Fig. 38. Temp. of inner surface of
shell plate (T. No. IV, midship). TP o M SP SP' A 1.1
Table 2.
Tension test results for heated test pieces
Thermal load before tension
test
Composition of glass fibre
4-, 5 -W I, d NO (1) ct, AV BV
Max. temp. reached
0
-g cd ). (=I a) -k z 5.9 Tensile force (kg) 4`il 4-5> zgzp
El Inner surface Outer surface Min. 1590 Max. 1830 Mean 1710 1:4 o 1 G.C+230R+450M +600M X 3+860R G.0 +455M x 2+605M X 3+ 600R+605M 7.0 1820 1920 1860 1 Nil Sprayed-up method CV 8.9 1670 2020 1710 1 G.C+ 600M X 6 C'V 7.3 1830 2070 1930 1 Test pieces G.0 + 23OR + 450M + 600M +860R A10 150 Un- known 2 6.3 910 1530 1200 .70taken from FRP plates
G.0 +455M x 2+605M x 3+ 600R+ 605M B10 140 Un- known 1-2 7.5 930 1780 1430 .77 after heating test Sprayed-up method C10 (Photo \ k 8 ) 130 Un- known 2 mm 9.2 1020 1670 1310 .77 4 <1.1 SP 170 700 2 7.4 900 1590 1200 . 62 4-1 713 SS 190 700 6.1* 350 590 440 .23 o .1 o o , or2 1-+ E G.0 + 600M x 5+450M BP 110 Un- known 2 6.9* 880 1270 1050 .54 BS 100 Un- known 2 6.8* 1260 1400 1350 .70 210 800 2-3 4.5* 530 790 610 .32 o AP Un- known Un- known 3 39* 520 670 600 .31 t.) AC Un- known Un- known 3-4 3.6* 510 590 560 .29
t
AS (Photo \ 9 ) Un- known Un- known 4-5 3.6* 370 650 520 .27 Test pieces Test results -.-
-I-, ,i) 2-3 FTable 2.
(Continued)
Thermal load before tension
Composition of glass fibre
-0... VI wc\/ ,1) -1-a ct ,.., .4_,. cl 1.U., w ;,..
Max. tern 13' reached
'..,o c),... bL;,-, - - tn En g w---,.., Tensile force ,(kg) c 4E1 bs) .- tv) I surnneif ace
0 t
-u et surface mill, r -Max _ a Men test 1:7-4°) °"`"" ,4 u t P.,,f_-,' ''''-o a, ca ,z...,l'
.._, i-4-r.-. TP 40 70 0 8.4 1510 1630_
1590 .87 10.0 -p4. ct ...., -cs cd ,-. .... 0 S? 90 330 1 7.8 1220 1420 1330 .69 9.3 , G.0 S3 ,so cp .., 0 .--. cs ..0 :_g co G. C -I-600M X 5+ 450M BP 40 470 6.6 1500 1900 1720 .89 13.1 40 640 2 7.0 1080 1440 1270 .66 9,7 Tv' a) F Un-ot.o o0 s..-P 4-, -cs o 0,, 4, ..,_: -.-ct, H ,.., el 47f, o 1:, o 1 I (Phote) 10 known known 1 7. 2 ' 1250 1720 1510 ,78 108 A Un- known Un- known G. C 7.4 1600 j 1980 1830 .[95 13.0fp
' Un- known 460 G.0 --1 6.4 1670 2020 1850 .'93 15.6* Zs SP 200 900 2 7.2: I 1190 1490 1350 I ,n.70 10. 1* rn a) rn y .;1.). a, 4-1 a) -c o -n"
-tC G. C.,1- 660M x 51-450M SS (Photo) \ 11 J 170 750 1-2 7.8 1 780 I 1950 1580 1 , 82 10.5 V) cp IE. cd E-i F known known 1 8:2 1460 1790 1660 .86 10.3 A 220 900 2 5.8* 1010 1230 1090 .56 9,8* _ Test pieces Test results INotes] 1.Five test pieces each having width of 19 mm were taken in accordance with the requirements of JIS K6911.
2.
Items affixed with * signify that the test pieces had thinner sectional area due to partial disintegration of glasS fibre layer at time of preparing the test pieces. G.0 signifies gel coat, R roving cloth, M chopped strand mat, and figures prefixed to letter M or It sighify glasS fibre density (g/in2) and those affixed to either of these letters signify the number of layers.
BS
-= - ' -I n - ° 4 0..12
Photo. 9. Test pieces. of 'AS' (Midship. model after T. No. I, II).
-,41-11-17, F ,B 110:1.3 mm , ft. r r4.4. breadth 1B)' 18.8min thickness ,(1) 8.6 mm breaking good (P)1020 kg VA burnt away blackened and charred
M changed colour
;
Photo, 8. Test pieces of `C 10' (after heating and tension tests).
111 r;47/3717PC B 18.5 mm
41. 3.7 mm
P' 470 kg
Photo A, Test pieces of 'F' (Midship model after T. No. IV),
layer separations were noticed in many cases between discolored and non discolored mats. As shown in Table 2, when one layer of glass fibre is burnt away, the strength becomes 70'80 ( %) of the original one; and when, two or three layers, 30-60 ( %) of the original one.
1' 7.4 mm P 1670 kg
.7/17 AI 1
zip; AFT, SS e iq5mrr, 4,.? . -I * 14 or 4 : 'D=s-rtJ.--FAL
-Photo 11. Test piece; of 'SS' (Aft model after T. No. III, IV).
r 6.2 m P 78 0 kg
5.. WATER SPRAY TEST OF ACTUAL TANKER LIFEBOAT Although the carrying-out the full scale fire -test on actual fireproof lifeboat in oil fire on the water surface will be desirous for verifying the safety of a lifeboat, it involves great difficulties..
Through the heating and fire tests described above, it has been
estab-lished that the characteristics of fireproof and thermal insulation of the FRP lifeboat are fairly good providing that its outer surface is entirely
covered with water film of sufficient thickness. Then, the water spray tests, were carried out to investigate the water film thickness distribution on two kinds of actual fireproof lifeboats, each sized 8.5 m in length and 3.2 m in breadth, and information necessary for the assessments of the character-istics of fireproof and thermal insulation of actual lifeboats was obtained.
Photo 12 shows a view of the water spray test on a lifeboat built by
Company C. The lifeboat and sprinkler system by Company B are closely resembled to those of Company C except for differences in which the lifeboat built by Company B is provided with a wheel house at its bow and additional sprinkler system of perforated pipe at its bow and stern.
Photo 12. Water sprinkling test of tanker life boat.
In the spray test, water film thickness distributions on the outer
surfaces of the lifeboat were measured in even keel, heeled and trimmed condition in consideration of possible rolls and pitches during the process of lowering or running on the water. The points of water film thickness measurements are as shown in Fig. 42. The flow rates of water during the test were assumed to be 95 m"/ h in lifeboat C, 70 m3/h in lifeboat B. The volume flow rates per unit width at the canopy from the above data would be approximately 100 / min.m in lifeboat C, and approximately 75 //min.m in the case of lifeboat B. The minimum flow rates which might be at the upper parts of side shell plate would be approximately 80 // min.m in
lifeboat C and approximately 60 //min.m in lifeboat B.
Fig. 43 shows the changes in water film thickness with time on the measured results concerning the heating test of vertically held FRP plate
type C
---- type B nproy Nozzle Hatch Perforated Pipe
1.01-=
2.0
Spray Nozzle Perforated Pipe
Gee) 5 1_=r: L.8.5 m .3.2 m D. I. 25m (type C ) I. 22m (type B) Dock
Fig. 42. Measuring points of water film thickness.
top0 S,de Ho rch DeckZ
(Outer sat/aces of the real tanker life boat of type C )
F.
L .W L.
Perforated Pipe
20 1/rnin.m 40 /trim. ITT
(Laufer Darts of the vertical at plate )
Fig. 43. Water film thicknesstime recording.
Type, Total Flow Rate Condition of Boat Engine (RPM) 0 Shell Side C) CD 2.0-3.0
-1.2-1.41.3-1.7g
Deck @Table 3. Sprinkling test results for tanker life boat
5 Deg. of Heel- 5 Deg. of Triming Angle 16 Deg. of Trim
Even I Even
I
Keel to to by the by the Keel I by the by the
Star- Port Stern Head Stern Head
bord C, 95 M./H (Estimated) - 0.9-1.61.2-1.91.2-1.71.5-1.9 15, 1.4-4.71.8--2.111 7-2 11.5-2.411.7-2.7
-r 10.6-0.7 1.0-1.50.8-1.21.2-1.71.2-1.41.1-4.2 ® 1 1.0-4.311.4-,2.01.5-1.81.5-2.1
-
1.2-1.51.1-1.51.3-1.i e 1 1 I 1 1.4-4.61.3-1.81.3-2.41.2-1.41.1-1.61.2-1.51.3-1.61.6-2.0 (6-1- 1.4-2.0
1.2-1.6 B, 70 M3/H (Estimated) 2.0-2.52.0-3.21.5-1.91.3-1.51.2-4.6 (A)-
;f3-__ I- 1.3-1.7
- 1.0-1.4 cC 1.6-1.91.0-1.42.0-3.00.9-1.21.7-2.2 T-
- 1.7-2.31.1-4.6 ® 1.1-4.7,0.8-4.5 0.8 1.51.6-1.9-
0., 1.1-1.61.8-2.21.1-1.5 g 0.7-1.3-
-
-31
in Section 2, and those obtained through the spray test of lifeboat C. The results of spray test are as given in Table 3 where no significant
differences are noted between the measured water film thicknesses of life-boat B and C. When omitting exceptional large values of water film thick-ness, the mean values of water film thickness measured on the outer surface of the lifeboats range between 1 and 2 (mm). When the lifeboat was heeled or trimmed to 5 degrees, no part of the water film was broken and it has been confirmed that the entire outer surface of the lifeboat was covered with
2310 2630 2620 2620 2630 2600 2600 2600 1830 1830 1840 1840 1850 2500 i 2500 2500 0.68 0.67 0.73 0.65 0.61 0.40 0.44 0.38 -0.20 -0.21 -0.21 -0.22 -0.24 0 0 -0.03 0.88 0.88 0.94 0.87 0.85 0.40 0.44 0.41 0.46 0.43 0.48 0.42 0.38 0.30 0.34 0.30 Pump (RPM) Pump Ps -w PD-Ps Spray PN Nozzle PD 1.6-1.7
-1.3-2.0-
-
- 1.1-.4.63.0-3.61.2-L5 1.3-4.8-
-
-1.1-.1.93.05.O-
--
- 2.0-3.21.3-2.31.1-1.41.2-4.71.3-4 © - 1.0-1.51.1-4.31.5-2.81.0-4..2-
-=--
-
-water film of 0.6 mm or more in thickness.
6. CALCULATION OF HEAT TRANSMISSION
From the results of the heating test of FRP plates in Section 2 and of the oil fire tests on model FRP lifeboat in Section 3, radiation absorption coefficient of water film on the outer surface of the shell, and heat transfer coefficient at the inner surface of the shell were determined. And calcula-tions of heat transmission, when an actual fireproof lifeboat is fully enve-loped in flames at sea, were worked out.
For obtaining correct value of heat transmission into the lifeboat which is enveloped in flames on the sea surface, it is necessary to solve the
follow-ing complicated problems : 1) phenomena of fire, 2) behaviors of flowing
down water, 3) mechanism of radiation and convection with respect to
flowing down water film and lifeboat body, 4) evaporation of water film, 5) various phenomena in association with smoking and combustion of life-boat body, etc. Although it is practically impossible to obtain detailed
answers to these complex matters at the moment, analysis was attempted on a simplified heat transmission model as shown below using electronic computer. model TOSBAC 5600, which is provided in the Information Sys-tems Section, Ship Research Institute.
6.1 Calculation Formula
When an FRP plate is not covered with water, amount of heat transfer to outer surface of the plate per unit area and time from combustion gas can be expressed by the formula below6, on assumption that amount of heat transfer by convection is negligible :
q,,= 4.88¢{(Td 100)4 (T0/100)4} ( 3 )
where
T flame temperature (°K)
To: temperature of outer surface of plate (°K)
total absorption factor
(I) is a function of effective flame emissivity E, shape factor, emissivity
of heated surface, and is a function of mean equivalent beam length of gas, T, , T, partial pressure of combustion gases and absorption coefficient of flame radiation.
The heat transmission into the FRP plate was considered to be
un-steady and one-dimensional in the direction of the thickness of the plate, as no significant difference on eac hnine points of outer and inner surface
temperature measurements could be noticed in the heating test of FRP
plate. The solution was calculated with linear explicit difference
( 8 )
33
the plate and for the effects of property values due to temperature changes. Plate thickness and heating time are divided into Jx and it, and
tem-perature T (P +1, n) after elapse of time (P+1) it at position nix is
ob-tained from
T(P + 1, n)=F IT (P, n + 1)-1- T (P , n 1)} ± (1 2F) T(P, n) ( 4 )
where
F =- a pit I (Jx)2 1/2
: thermal diffusivity of plate
As an initial condition temperature distribution T (0, 11) in the
direc-tion of plate thickness at time t=0 is given, and as boundary condidirec-tions temperatures of the outer and inner surfaces of the plate at an arbitrary
time, T (P, 0), T (P,N) are given. When thermal fluxes q (P. 0) , q (P, N)
are given in place of outer and inner surface temperatures, these tempera-tures are obtained from the following equations :
T(P +1, 0)=2F T(P, 1) + (1-2F)- T(P , 0) + 2A F q(P , 0)
(5)
T (P 1, N) = 2F (P,N - 1)+ (1 2F) T (P, N)-2A q(P,N) ( 6 )
where
A= ix 12 D: plate thickness (=Nix)
: thermal conductivity of plate
Heat flux q (P, 0) of the outer surface of the plate can be approximated as below by using the temperature gradient at the outer surface of the plate :
q(P, 0) = {T(P+ 1, 0) T(P, 0)1/(2A -F) +{T(P, 0) T(P, 1)11A
(7)
Assuming that the heat transferred to the inside of the lifeboat does not get out, the following equation can be obtained with respect to heat flux q (P, N) entering from the inner surface of the lifeboat to the inboard air :
q(P, N) = ce{T(P , N) T (P)} = r c
V JT
S where
iT ,= T ,(P)
T(P-1)
TA: inboard air temperature
V: inboard air volume
S: heated surface area of plate
,
1: specific weight of air
c: specific heat of air
: heat transfer coefficient at inner surface of plate
Heeat flux to the outer surface of plate q(P, 0) is equal to the increase of accumulated heat of the shell plate and inboard air with time ; i.e.,
q(P, 0) = q(P, N) + 'ix- 'ET {T(P,n)T(P - 1, n)}
P zit
where
e n : specific heat of plate specific weight of plate
In the case of a plate cooled by water running along the surface, the amount of heat by combustion gas to the outer surface of the plate is the sum of heat by radiation transmitting the water film and heat by convection from the water film. However, the problem is extremely complicated as it must be solved with unsteady-state partial differential equations while pay-ing sufficient considerations with the velocity and temperature distribution of running down water film associated with evaporation. Therefore, we employ a simplified method as follows. Assuming that the heat flux equiva-lent to (1 e- AL)p is absorbed by water under Beer's law while heat flux passes through water film of thickness L. then heat flux q' which reaches the outer surface can be expressed by the following equation :
q =e-K L (10)
where
K: radiation absorption coefficient of water
For reference, infrared absorption coefficient of water radaited from a propane gas infrared heater is shown in Fig. 44.
6.2 Case Study on Heating Test of FRP Plate
By substituting equation (4) with the experimental data shown in Figs. 6 to 11, the temperature distribution in the direction of plate thickness was obtained as in Fig. 45, and heat fluxes at the outer and inner surfaces of the plate were calculated by using equations (8) and (9). The average heat flux at the outer surface of the plate is shown in Fig. 46. When the volume flow rates per unit width are 10 and 17.5 (//min.m) , the heated surface was locally and intermittently burnt away as shown in Figs. 8 and 9, and then heat fluxes were also unstable. When the flow rates were 0, 25 and 40 (1 min.m), the heat fluxes reached their maxima in 2 to 3 minutes after the beginning of heating, and became constant after that time. Fig. 47
C2 OL/MtN 200 7.- 0 n',. 2 ',,s? o -..., 100 "/ ----,-..z. /.0 0.5 C 3(17.5i 92(25) C3(40ro 4 6 .8 10 DEPTH /THICKNESS
Fig. 45. Temp. distribution of FRP
plate.
1- EXP(-KL)
0
0
HEAT
SOURCE INFRARED HEATER( C31-1.) 690°C
K ABSORPTION COEFF I CENT 3.5mrri
--.5 Mrci'
0.5 1.0 1.5 mm)
THICKNESS OF WATER. L
Fig. 44. Radiation absorption through water.
C3(0) C2 0) C2 (10) C3(17.5 ) 82(25)5) C3(4 OL/MIR) TIME (MIN.)I 0
Fig. 46. Average heat flux at the outer
surface of FRP plate. 35 ,... yr, C' ,.. '5 ..)P/4,. Lu Z 04,,,, ...,-'.... 0 O0 0
shows the average heat flux at the inner surface which becomes nearly
constant approximately 4 minutes later than that shown in the case of the outer surface.
When the combustion gas temperature is much higher than that of the outer surface, the ratio of the heat flux at the outer surface to black body
emissivity power E at the combustion temperature can be expressed as
below :
go' IEb=0.e-xL
Shown in Fig. 48 is the value of q' 1E, for FRP heating test with water cooling. The calculated value) of total absorption factor under experi-mental conditions is about 0.4 ignoring generation of combustion smoke, and then the value of q'/E which is 0.2-0.3 from the experimental result under non-water-cooled condition, is considered nearly appropriate. If the total absorption factor is calculated by substituting equation (11) with the value given in Fig. 48 and K=5 mm from the experimental result, then we
obtain c5 = 0.23.
The heat transfer coefficient a from the inner surface of the FRP plate to the air in model box, calculated by using equation (8) and the experi-mental result, is 1,-3 (Kcal/m211 °C) which is in approximate agreement with that of the steady-state natural convection of the vertically held smooth
SO: HEAT FLUX AT THE OUTER SURFACE
0 Eb: BLACK EMISSIVE POWER
70 60 -J 050 D40 -J <30 Ui 20 I 0 C3(0) C2(0) C2(10) 8 I0 TIME (MIN.) Fig. 47. Average heat flux into the air
in box. to (L/MIN.) 0 .o... x 17.5 w 25 oe, 8 40 0 d 0 2 4 6 10 12 14 16 (8 TIME (MIN.)
Fig. 48. qo'/Eb for FRP heating test.
C3(17.5)
C3(40 L/MIN ) 82(25)
1
flat plate.
6.3 Case Study on Oil Fire Test of Model 'FRP Lifeboat
The same procedures were taken in calculating the heat of the model lifeboat as those used in the case of heating test abovementioned. Figs. 49 to 52 show the mean temperatures and inner surface of shell plate, and inboard air.
The results of temperature measurements of actual FRP
900 8001 700 00 a_ 500. 400 300 200, 100 200 ° 50 --f-I 011 SD ifAFT. -.IV MI F IV AFT._ c }REFERENCE 2 v) 0, 8 10 TIME ( MIN. ),
Fir. 49, Average temp. of fire..
REFERENCE?)
1
2
46
A'TIME .( MIN. )
Fig. 51. Average temp. of inner
sur-face of shell plate.
400 300 800 700 t 0 0 F
500
200-tO0 8 10 TIME (MIN.)Fig. 50. Average temp. of outer
sur-face of shell plate.
15 '100 Lb.( 2 f .4A 'REFERENCE 21, A-A` transmission of FRP plate of fire, outer fireproof life -50 6 8 10 TIMF ( MIN.)1
Fig. 52. Average temp. of inboard air.
uJ .37 I 00 0
/
(boat are also shown for reference2,3'. The actual lifeboat was 8 m in length;
(mm) in plate thickness and an oil fire test tank measured 18 x 13.2 (m) .
The temperatures represented by symbol E are those measured on the
lifeboat which was sprinkled at a rate of 65 m" /II while the boat was floated in the centre of the water surface and the fire burnt itself out in seven
minutes and 30 seconds. The temperature represented by symbol
r
are those measured on the lifeboat which was in the middle of the water tank and sprinkled at a rate of 90 m",/h in its lifted position at an elevation of 1.2 m above the water, and air foam fire extinguishing operation was started in five minutes after the ignition. Ineither case, the measured temperatures at the inner surface of the shell and inboardair are in close agreement with those measured in the test No. III under the standard conditions of water sprinkling.From the experimental results of the oil firetest of the model lifeboat, temperature distribution across the shell plate and heat flux at outer and inner surfaces were calculated.
The temperature distribution in the direction of plate thickness when the temperature of the outer surface reached its peak is shown in Fig. 53.
800 700 600 T' 500 co \,,,'.2, 0 0 x ,7.,, . o a: a z400 cr til D 200 I 00 ,
Fig. 53. Temp. distribution of FRP
shell plate.
TIME (MIN.)
Fig. 54. Average heat flux at the outer
surface of shell.
In the case of the test No. II with non-water-cooled condition, the temper-ature of the plate at its half the thickness reached as high as approximately 300°C. The depth featured by this temperature is nearly identical with the
depth of burn damage of the shell plate shown in Table 2.
The mean heat flux into the outer surface of the shell plate due to the fire is as shown in Fig. 54, and exceeded 25,000 Kcal/m2h, when no water
. --. I (.13 ,fl CD 00 al ...z A, - A 7 C r) - X F AFT ,, A . % a 2 4 6 .8 1.0 DEPTH/ THICKNESS
a
IN.
Fig. 55. Average heat flux into the inboard air.
Although the value of heat transfer coefficient from the inner surface of the plate to the inboard air underwent considerable changes with time, the
mean value of 1-3 (Kcal/m' h) was in close agreement with the result of the heating test of FRP plate.
By substituting equation (3) with the mean heat flux to the outer sur-face of the shell under non-water-cooled condition, we obtain total absorp-tion factor 0=0.27 which is larger by about 20% than that obtained in the
heating test of FRP plate. When the experimental results of K=5, mm
shown in Fig. 44 and water film thickness of L=0.5 mm at the critical flow rate on the vertically held FRP plate are inserted into equation (10) , the
value of becomes approximately 2,000 Kcal/m". h which is in close
agree-ment with the experiagree-mental results of the test No. III shown in Fig. 54.
6.4 Case Study on Actual Lifeboat in Fire on the Sea Surface
It would be very difficult to predict precisely the time required for a lifeboat to run away from fire on the sea surface after being lowered on the water and heat load to which the lifeboat would be subjected. Therefore, making reference to the paper, it was assumed that the lifeboat would be subjected to fire on the sea surface at a temperature of 1000°C for a period of 5 minutes.
When both the mean flame emissivity and shape factor are presumed to be one respectively, the total absorption factor 0 will be 0.7 in considera-tion of emissivity of heated surface. Absorpconsidera-tion factor of radiaconsidera-tion by water
K=5 mm, and the temperature of fire T,= 1000+ 273 (°K) are inserted into
equation (10) to obtain the value of heat flux at the outer surface of the 39 sprinkling was applied. However, the mean heat flux in the case of the test No. III with water sprinkling at the critical flow rate of 25 //min.m was only 2,500 Kcal/m2-h. The approximate mean heat flux into the inboard air was 150 Kcal/m' h under non-water-cooled condition and 20 Kcal/m' h
under water sprinkling at the rate of 25 //min.m as shown in Fig. 55.
/
/
\
..
A
,-,---lifeboat. The computed results are as shown in Fig. 56 where it is approxi-mately 90,000 Kcal/n/2- h under non-water-cooled condition ; approxiapproxi-mately
4,500 Kcal in= h under water-cooled condition with water film thickness of
0.6 mm. The solid lines and broken lines shown in Fig. 57 are the
temper-TEMP. OF FIRE :1000°C
K 5000/m (I) 0.7
0 .3 .6 9
THICKNESS OF FALLING WATER FILM (MM)
Fig. 56. Calculated heat flux at the
outer surface of boat.
VOLUME OF INBOARD AIR ---- 25 tr3
HEATED SURFACE OF BOAT---2 5 m2
HEAT-TRANSFER COEFFICIENT AT THE INNER SURFACE OF SHELL
-- 3 KCAL / M2. H°C PROPERTIES OF FRP SHELL PLATE
(X: .174 KCAL/MFOC
--- - - C: .25KCAL/KG,C
r: 1550 KG/M3
T
TEMP. OF OUTER SURFACE TEMP. OF I NNER SURFACE
^0
oc) --TEMP. OF INBOARD AIR
1.0 TEMP. OF FIRE :000°C ri K ,5000/m CD . 0.7 M t .5 MIN. ujO 0 7.8, a Pit:e., 0 0 1.0 0 0 0.6 0.7 5 6 7 8 9 10 THICKNESS OF PLATE (MM)
Fig. 57. Calculated temp. of boat in
fire.
atures of FRP shell plate on its outer surface and inner surface in five
minutes respectively. Assuming that the inner surface is thermally
insu-lated, the temperatures of inner and outer surface are calculated using
equations (5) and 6). And the temperature distribution in the direction of plate thickness is computed by using equation (4). The dot-dash-line inthe figure represents the calculated results of the inboard air temperature in five minutes which are obtained on the 8-meter actual tanker lifeboat by substituting equation (8) with the following values :
Area of heat transfer from the inner surface of boat to inboard air A=25 m2
Inboard air volume V=25
T °
0
