Failure Knowledge Database / 100 Selected Cases

LP Gas Explosion from the Overturning of a Tank Truck
Oct. 26, 1965, Nishinomiya, Hyogo
AKATSUKA, Hirotaka (High Pressure Gas Safety Institute of Japan)
KOBAYASHI, Hideo (Tokyo Institute of Technology)(Summary)
During the nighttime of October 26th, 1965, a five-ton tank truck running on a national highway in
Nishinomiya City overturned due to the improper steering by the driver who fell into a doze while driving.
Sustaining a shock from the overturn, the safety valve and the slip tube level gauge protruding from the topof the tank truck were broken and caused LP gas to blow out.

The spilled LP gas diffused into

approximately 1m thick white fumes, which crawled ahead across the range of 200 m along the nationalhighway.

About five minutes later, LP gas ignited from an unknown source.

Numerous ignition sources

are conceivable, but the real one is still unknown. This fire resulted in a great disaster causing 5 deaths,
26 serious and minor injuries, and 31 residential destructions.
120,000,000 yen.

The estimated amount of damage was

The carrier company could not afford to compensate for the total amount of damage,thus causing the compensation negotiations to proceed slowly.

1. Component
Five-ton tank truck (inside diameter: 1,750 mm, length: 5,030 mm, barrel thickness: 12 mm, material:
60 kg class high strength steel) (See Fig. 1)

2. Event
During the evening hours, a five-ton tank truck running on a national highway in Nishinomiya City,
Hyogo was overturned due to the improper steering by the driver who fell into a doze while driving.
Figs. 2 and 3)(SeeThe tank truck, which was estimated to be running at a speed of 60 km/h or more,

overturned just before the pedestrian overpass, slid away about 8 m, and crashed against the support of theoverpass.
Sustaining a shock from the overturn, the protruded safety valve (size 50A) and slip tube level gauge
were damaged.
situation.

Given a shock such as this, a safety valve of any material would break down in thisThe tank truck struck the curb, causing the right side of the truck (seen from the loading

position) to be dented 110 mm deep, 1,200 mm long, and 600 mm wide.

However, no areas were foundwhere LP gas leaked, and no marked abnormalities were identified in the other fittings, either.
The gas blown out from a rupture (50A/19.6cm2) kept spreading, ignited, and exploded about fiveminutes after the initial blowout. Assuming that the LP gas freely escaped from the hole, most of the LP
gas escaped in about five minutes before the inflammation.

The escaped LP gas developed into about 1 m

thick white fumes, which crawled ahead across the range of 200 mm along the national highway. (See Fig.
4)

Part of the fumes filled the southeast area of the overpass and went downwind beyond a wall (about 21Failure Knowledge Database / 100 Selected Casesm high) into the neighboring residential area.
wall fell down toward the sidewalk.

This was also identified by the fact that the concrete-block

The LP gas diffused in such a wide range that numerous ignition

sources were conceivable but none of them has been identified as the real one.

Yet, the possible

inflammation sources could be narrowed down into: (1) Inflammation sources in the neighboring private
residences (such as thermostat of electric refrigerator, pilot lamp of gas range, motor of an outside homepump, or embers in an incinerator); (2) fire sparks from exhaust fumes of running vehicles; and/or (3) theengine or electric sparks from the tank truck.

3. Course
The tank truck that caused the accident left the garage at Higashi-nada Ward, Kobe City on Oct. 25th atabout 7:00 p.m. and reached a fueling plant at Arita City, Wakayama on Oct. 26th around midnight.

Atthe plant, 5,000 kg of LP gas, which was mainly composed of propane gas, was loaded onto the truck inabout 20 minutes. After that the truck set out on its return at about 0:50 a.m. on the same date.

Sometime after 3:00 a.m., the driver, who had felt drowsy, turned the wheel left hastily to avoid a black
passenger car crossing ahead from the right.

However, noticing a light car running at left in the direction

as the truck went, the driver suddenly turned the wheel right in a panic, causing the truck to lose its balanceand overturned.

4. Cause(1) Falling asleep at the wheel
The direct cause of the accident was the driver dozing off while driving.

All drivers who transport

hazardous substances should be well aware that they are driving a potential weapon/bomb and attend totheir tasks in a perfect physical condition at any time.
(2) Damage to protruding parts
The cause of this accident having developed into such an extensive LP gas explosion was the leakage ofLP gas from a punctured hole on the parts which protrude from the truck.
safety valve and the slip tube level gauge.

The parts in question were theIt was ironic that these safety devices contributed to the spreadof a disaster.

5. Immediate Action
There was no possible action to take against this accident, partly because it happened at midnight andpartly because the time from the start of the leak of LP gas until its inflammation was short (five minutes).
In the event of a large-scale LP gas leak, however, it is important to notify it to the fire department andinform to the local residents to stop using fire or flammable substances and evacuate to safety.

6. CountermeasureWith this accident as a turning point, the following amendments were made to the enforcementregulations of the High Pressure Gas Control Law (Dec. 1965):(1) Notification system of a transport plan2

Failure Knowledge Database / 100 Selected Cases(2) Limitations on transport routes(3) Use of two drivers for a transport of 200 km or more
(4) Prevention of damage to fittings such as valves and level gauges.

7. Knowledge○ Design equipment and fittings with latent risks in mind.
To design equipment and fittings, assume the possibilities of an accident, and design such a structurethat can prevent the spread of an accident.

8. Information Source(1) Discussion on the Report of Tank Truck Accident in Nishinomiya City (1965): Industry Div., Dept. ofCommerce, Industry and Labor, Hyogo Prefecture.
(2) Fusion and Explosion of Oxygen Gas Containers in Process of Filling Operation

9. Primary Scenario
01. Carelessness
02. Fatigue or Poor Health
03. Lack of Sleep/Rest
04. Regular Movement
05. Dangerous Movement
06. Drowsy Driving
07. Traffic Accident
08. Overturn of Tank Truck
09. Failure
10. Fracture/Damage
11. Rupture of the Safety Valve/Level Gauge
12. Leakage of LP Gas
13. Secondary Damage
14. External Damage
15. Fire
16. Bodily Harm
17. Death
18. Accidental Death
19. Loss to Organization
20. Social Loss
21. Destruction of Residences by Fire
22. Damage to Society
23. Social Systems Failure3Failure Knowledge Database / 100 Selected Cases

24. Compensation for Damages
25. Difficulties in Compensation Negotiations

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Failure Knowledge Database / 100 Selected Cases

Slip-tube typelevel gauge

Safety valve

Level gauge
support fitting

3

Tank volume : 11m

Fig. 1

Tank lorry.

5Failure Knowledge Database / 100 Selected Cases

Fig. 2Turned lorry on its side (Rear view).

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Failure Knowledge Database / 100 Selected Cases

Fig. 3

Turned lorry on its side (Front view).

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Failure Knowledge Database / 100 Selected Cases

Direction of wind

Manhole blown away
Hanshin rail way

Painted door surface burned
OsakaTree and plant burnedand died.
Polyestr burneddRoa
nalatio oad)Nshin ional RtHan#2 43 Na#(Kobeca. 100 windows
glass broken

Pond

Burned out area

Koroen primary school

Fig. 4

Rough sketch of accident spot.

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