Failure Knowledge Database / 100 Selected Cases

Fire of Petroleum Tank, etc. by Niigata Earthquake
June 16th, 1964, Niigata, Niigata pref.
AKATSUKA, Hirotaka (High Pressure Gas Safety Institute of Japan)
KOBAYASHI, Hideo (Tokyo Institute of Technology)(Summary)
The N iigata earthquake on June 1 6th, 1 964, ha d a m agnitude of 7 .5, a nd a se ismic scale of 6. T heearthquake c aused a n urban bridge t o f all d own, ap artment b uildings constructed w ith st eel rei nforced
concrete to be overturned, and fires to break out in petroleum tanks. These incidents caused a different typeof damage compared with past incidents, and t hey attracted notice as new types of urbane disasters. TheNiigata earthquake was al so t he first s eismic dis aster i n Jap an wh ere the li quefaction o f the g roundattracted notice. Among the disaster incidents caused by the earthquake, five crude oil storage tanks in arefinery caught fire and continued burning for two weeks, spreading into the surrounding area and burning
down a total of 286 adjacent houses. One of them was a 3 0,000kL floating roof type tank, 51,500mm indiameter, and 14,555mm in height, which was fully stocked with oil. The cause of the fire was ignition bysparks generated by the collision of the floating roof with the side wall, which in turn was caused by themovement of the cr ude oil by t he slos hing phenomenon. The fire a lso s pread to t wo sp herical tanks f or
LPG made of 70 kg /mm2 (700MPa) cla ss high tensile steel , 1, 200m3 in vol ume, 13 ,240mm in in ner
diameter, and 25mm in thickness, resulted in the splitting and buckling of a supporting leg. Furthermore, allof the equipment in t he r efinery, including h orizontal set tanks a nd frei ght ta nks, w ere d amaged. T heNiigata ear thquake w as al so on e of th e most serious seismic disas ters to af fect chemical pla nts, and it
brought about many precepts such as the increased perception of the liquefaction phenomena of the sandy
ground, the importance of investigations into earthquake-proof designs for tanks, and the importance of theapplication of fire-proof concrete coating to supporting structures.
1. Event
Each tank in the refinery was shaken by the earthquake in the north and south direction, coinciding withthe d irection to th e seism ic ce nter (Fig ures 1 a nd 2). The flo ating r oofs of fi ve c rude o il st orage ta nks
shocked, a nd shaking motion of o ne of t hem was co mplicated by it s incl ination to th e w est, w hich w as
caused by subsidence of the ground that was associated with the soil liquefaction phenomenon. "Sloshing"is defined as the phenomenon of vibration induced on the free s urface of a li quid contained in a vessel by
the shaking of the vessel itself (Figure 3). In the sloshing of large vessels such as petroleum tanks, the forceof im pact t o t he t op a nd the ne gative pressure to the side w all are serious problems. As a result of t heshaking of th e floating roof, the cru de oil flowed out of the t op of the tank, fell down along the side wall,
and was ignited by the sparks generated by the collision between the floating roof and the side wall. The
crude oil storage tank yard was located adjacent to the main plant area. That is, the tank was within 40m of
the plant area, and 48m away from the nearest equipment. A part of the crude oil flowed into the main plant
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Failure Knowledge Database / 100 Selected Cases

area and caused fires in the catalytic conversion plants including the reactor, a part of the heating furnace,
the heat exchangers, the gas separator, and a part of the compressor.
Various damages occurred as a result of the liquefaction of the ground. The "liquefaction of the ground"occurs when seismic vibration causes sandy ground saturated with underground water to become a li quid.
Buildings t hat ha d been s upported by the gr ound los e th eir s upport an d become til ted or sin k into theground. O n the other hand, str uctures that h ad b een bur ied u nderground are lifted out of t he ground(Figures 4 a nd 5). The gro und l iquefaction phenomenon caus ed un even settlement to th e tanks, which
resulted in the def ormation an d fai lure of th e p ipes (Figure 6). The oil fence cracked to expose th e
reinforced steel bars, which in turn suffered from thermal expansion by the fire, causing the fence to lose its
strength and col lapse. Underground water rose up t o the s urface by the gr ound liquefaction, fill ing thecampus together with the sea water that had come in with the earthquake induced tidal wave (Tsunami). Oilflowed o ut t hrough cracks in the tanks a nd pi pes a nd was sprea d by the fl ood w ater, ca using t he f ire tospread at an accelerated rate.
As a result of the fire, one of the leg poles supporting a spherical tank for LPG split and buckled due toinner pressure from heated rain wat er that had been seal ed in the pole during th e con struction wo rk.
Because a part of the refinery campus was at sea level, the flow of underground water and sea water caused
fire to spread extensively. The surrounding houses to which the fire spread were divided into four areas.
Houses in one of t he areas located more than 200m from the refinery caught fire because the ground levelof the area was lower so the burning oil was carried by the flow of water.

Houses in another area locatedat a distance of 30 to 50m lee side of the yard containing the small size tanks (ca. 10m in diameter) in therefinery caught f ire immediately after the outbreak of the fire at the plant. The other two areas were very
close to the refinery, with a part of the houses located at a distance less than the length of the diameter of
the tanks. The ground level in those areas was also low enough that the sea water carrying the burning oil
flowed into the area, causing the fire zone to expand rapidly.
2. CourseThe Niigata earthquake that occurred at 13:02, June 16th, 1964 had a magnitude of 7.5, and a seismic
scale of 6. The earthquake caused five crude oil storage tanks in refinery to catch fire. The fire spread over
the tanks and the tank yard. The fire was remarkably difficult to extinguish, one of the tanks continued toburn until 17:00 on June 29th, and another four ta nks burned until 10:00 on June 24th. The burning crude
oil t hat fl owed out during the fire ca used fires t o e xtend to t he i ntegrated plant containing t he heat ing
furnace, the heat re covery boiler, the reactor of the catalytic conversion process, the hydrolysis treatment
equipment, and the bott om of the hydrolysis reactor for the desulphurization process. A part of the hi ghvoltage electric substation was also burned down by the oil that flowed out of the tanks.
3. Cause(1) Sloshi ng phenomenon
The floating roof ty pe tank is considered to be safer than the cone roof type tank because the floating
roof minimized vaporization loss of the stocked oil by eliminating the vapor phase. However, the danger2

Failure Knowledge Database / 100 Selected Cases

associated w ith t he s loshing p henomenon is greater f or th e fl oating ro of t han for th e c one r oof. T his
disaster ha ppened as a res ult of t he fo llowing pro cess; th e flo ating roof w as sha ken vigorously by th eearthquake t ogether wi th t he uneven se ttlement of t he t ank caused by the ground li quefaction, w hichresulted in ignition of the oil by sparks generated by the collision between the floating roof and the sidewall. T he s parks w ere ge nerated by th e metal to uch s ealing be tween t he fl oating roof a nd the side w all.
Recently, soft touch sealing composed of synthetic rubbers or urethane foams has been used instead of themetal touch sealing.
(2) Insuf ficient earthquake-proof design
Insufficient i mprovement of th e basic fou ndation for hea vy str uctures as ta nks and i nsufficient
flexibility of the pipe line against the subsidence of the ground resulted in the amplification of the damages,
especially in the areas of ground liquefaction and of zero ground level ground into which sea water could
easily flow . I n fa ct, som e of t anks that were l ocated on t he im proved basic fo undation suf fered li ttle
damages from the uneven settlement. At the initial stage, the oil fence helped to preve nt expansion of thefire, however, later it collapsed because of insufficient earthquake-proof design.
4. Immediate Action
When an earthquake occurs, operators must shut the valves of pipes in order to prevent oil from flowing
out, and they must stop boilers and furnaces to eliminate possible sources of ignition. A large scale refinery
fire is tremendously difficult to extinguish. Therefore, measures preventing the expansion of refinery fire，such as early detection of outflowing oil or spreading fire, are very important.
5. Countermeasure
In response to the accident, the following countermeasures have been taken;(1) Application of the vibroflotation method in order to improve the basic foundation.
The v ibroflotation is a method for co nsolidating and ti ghtening lo ose an d soft ground as fol lows; thevivroflot (vibrator with water jet) is s lowly lowered wh ile vibrating to the bottom of soil layer, and then it
gradually withdrawn while feeding sand into the area.
(2) Improvement of the floating roof type tank.
The metallic seal mechanism was elim inated entirely and the side wall was heightened to prevent theoutflow of oil.
(3) Protection of the supporting legs of poles for stock tanks.
The reg ulation requ iring t hat t he l egs be co vered w ith fire-pr oof concr ete of m ore than 5 0mm inthickness was introduced.
(4) Increase of earthquake-proof considerations for the piping.
Design s uch as the spr ing sup port a nd the flex ible j oint ha ve b een a dopted d epending o n t he k ind ofpiping. Moving underground piping above ground has made it easier to find defective parts during ordinary
operation and to take necessary actions quickly in the case of an emergency.
(5) Increase of the earthquake-proof performance for the oil fence.

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Failure Knowledge Database / 100 Selected Cases

Applying a flexible structure to the joints of the oil fence and introducing redundancy of the oil fence
have increased its earthquake-proof performance. If th e inner fence is broken, the outer fence prevents theoil from flowing to the outside.
6. Knowledge○Never skimp on consolidation of the ground foundation.
Refinery and petrochemical complexes are usually constructed near the coast, where the ground is oftenloose and soft. If im provement of t he ground foundation is insufficient, then uneven settlement can easily
occur for tanks as a result of an earthquake. Also, other accidents such as [Heavy oil flowed out by break oftank at Mizushima on 1974] can occur.
○Consider all of the dynamic situations that occur as a result of an earthquake.
Piping and its related parts will fail as a result of an earthquake if the tank, the emergency shut valve,
and the piping are no t set on the same foundation. Disasters like [Leak of LP gas from piping of the l ow
temperature stoc k t ank at South H yogo pref. ear thquake on 1995] ca n als o occur as a re sult of anearthquake.
7. Discussion
Fires and other disasters resulting from failures of petroleum tanks as a result of earthquakes around theworld that are comparable to this accident are as follows;(1) 1933, Long beach earthquake, California, USA, Magnitude 6.3.
(2) 1960, Chile earthquake, Chile, Magnitude 7.8.
(3) 1964, Alaska earthquake, Alaska, USA, Magnitude 8.4.
(4) 1978, Miyagi prefecture offshore earthquake, Japan, Magnitude 7.4.
(5) 2003, Tokachi offshore earthquake, Japan, Magnitude 8.0.
In the Tokachi offshore ear thquake th at occ urred on September 26th, 20 03, a to tal fire of a naphtha
storage tank occurred. A total fire is a fire that covers the total surface of top of the tank. This kind of fireoccurs after t he fl oating ro of sin ks d own, a nd it is d ifferent from t he ri ng fire t hat occurs as a resul t ofleaked o il around t he p erimeter o f t he t ank. The cau se of the i gnition o f that fire i s still unknown. The
floating roof was thought to have sunk because it was broken after the sloshing phenomenon continued fora long period. The w eakness of the f loating roof type storage tanks against the sloshing phenomenon waspointed o ut i n this c ase as w ell. Many t anks t hat did n ot c atch f ire a nd a part of t he p iping w ere s till
damaged by this earthquake, which showed that the countermeasures adopted against earthquakes were stillinsufficient.
8. Information Source(1) Report of Field Investigation on Niigata Earthquake, September 14, 1964, Mining Department, MITI.

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Failure Knowledge Database / 100 Selected Cases

9. Primary Scenario
01. Insufficient Analysis or Research
02. Insufficient Environment Study
03. Lacked Research for Foundation of Ground
04. Production
05. Hardware Production
06. Engineering Work
07. Insufficient Ground Improvement
08. Failure
09. Deformation
10. Liquefaction Phenomena
11. Bad Event
12. Thermo-Fluid Event
13. Petroleum Tank
14. Sloshing Phenomena
15. Bad Event
16. Chemical Phenomenon
17. Spark Generation
18. Ignition
19. Firing
20. Secondary Damage
21. External Damage
22. Extended Fire
23. Burned Down of Houses

5Failure Knowledge Database / 100 Selected Cases

RefineryFig. 1Site of refinery.

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Failure Knowledge Database / 100 Selected Cases

BoileBoileAdjacentfactory

Oldfactory

Niigata Refonery,Showa Oil Co.

OfficeTransformationroom

Leadadding

FlarestackFurnace

Firepump

Products tank
Reactor
New Factory

Integrateplants
Crude oil pump

Fig. 2

Damaged part of refinery.

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Failure Knowledge Database / 100 Selected Cases

Floating roof(Shaking)Floating roof
(Ordinary)

Earthquake

Fig. 3 Sloshing phenomenon.

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Failure Knowledge Database / 100 Selected Cases

http://www.jecc.co.jp/tech/bumon_head/frame_kanbo.html）
Fig. 4 Liquefaction of ground (Kawagishi-cho).

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Failure Knowledge Database / 100 Selected Cases（http://www.jecc.co.jp/tech/bumon_head/frame_kanbo.html）
Fig. 5

Uplifted manhole by liquefaction (Near girder bridge of Echigo-line).

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Failure Knowledge Database / 100 Selected Cases

BrokenG.L.

FailedFig. 6

Damage of tank attachment piping.

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