GROWTH THROUGH THE CREATION OF SHARED VALUE

SPECIAL FEATURE 2:
THREE INITIATIVESFOR SECURITY, SAFETY,
AND RELIABILITY

Prevention

Emergency

Restoration

Supply Control Center

Sitting on top of four colliding tectonic plates, Japan is known as anearthquake-prone nation. As a provider of public services to thenation’s economic center, it is our duty to enhance our social value bycontinuing to ensure a stable supply of energy, while making safety
the foremost priority.
Natural disasters pose a serious threat to Tokyo Gas. Constantly awaresystem is based on the three pillars of “prevention,” “emergency,” and“restoration.” Preventive measures help minimize damage when a major
earthquake occurs; emergency measures prevent secondary damage,such as fires and explosions; and restoration measures target the resumption of gas supplies as soon as possible. Ensuring that these three disaster preparedness pillars are firmly in place is intricately linked to raising oursocial value and enhancing the Tokyo Gas brand, which centers on “secu-TOKYO GAS ANNUAL REPORT 2011that a disaster could occur tomorrow, the Company’s crisis managementrity, safety, and reliability.”

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SPECIAL FEATURE 2:
THREE INITIATIVES FOR SECURITY, SAFETY, AND RELIABILITY

1PREVENTIVEMEASURES

We Have Built Production and Supply Facilities

City Gas Production Terminals

Using Advanced Seismic Design Standards andLNG transported by LNG vessels is stored in underground

We Have Doubled and Tripled Safety Precautions.

tanks at three terminals on the shores of Tokyo Bay. There,

City gas produced at our three LNG terminals oncity gas.

the LNG is vaporized and odorized before being sent out as

the shores of Tokyo Bay is supplied to households,
office buildings, commercial facilities, and factories
via an extensive pipeline network. Gas is sent fromthe terminals through a high-pressure trunk pipelinethat loops the Tokyo area, then through a networkof medium-pressure pipelines, which branch into
many low-pressure pipelines.
These city gas production facilities have been
built so that they are capable of withstanding earthquakes on a scale similar to the Great HanshinAwaji Earthquake (M7-class earthquakes).
The surface level of the liquid stored in some ofthe largest underground tanks in the world isLNG Vaporizers
LNG is pumped into aluminum pipes, andthe liquid is warmed by the seawateraround the pipes, which transforms LNG
back into its gaseous form.

always below ground level. Consequently, even in
the unlikely event of a crack or break in a tank, theLNG could not seep outside.
Tokyo Gas is able to provide stable supplies ofcity gas using its safe production and supply system, which has been constructed to withstandmajor earthquakes and other natural disasters.
Nonetheless, we have had to face the reality thatthe recent Great East Japan Earthquake triggered
unexpected developments that caused serious accidents. Therefore, we are currently investigating
measures needed to ensure an even higher safety
threshold, which we will implement in due course.

Underground Tanks
LNG is stored in underground tanks thatTOKYO GAS ANNUAL REPORT 2011

are made to withstand M7-class earth-Tokyo Gas Uses Strong Pipelines Capable ofquakes. Even in the unlikely event ofWithstanding Movements in the Earth’s Crust.

damage to a tank, the LNG cannot leak

Because almost all of our pipelines are underground,always below ground level.

ground movement during an earthquake can have a
direct impact on them. This is why Tokyo Gas uses
high-pressure and medium-pressure pipelines madefrom welded steel pipes that provide exceptional

High-Pressure Pipelines
The high-pressure pipelines that connect one terminal withstrength and flexibility. In both the Great Hanshin-

another and terminals with governor stations are made of strong

Awaji Earthquake and the recent Great East Japan

steel pipes that are welded together. Tokyo Gas patrols theEarthquake, the pipes exhibited excellent earthquake resistance.

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because the surface level of the liquid isground above the pipelines on a routine basis. Our high-pressurepipelines withstand the force similar to the Great Hanshin-Awaji
Earthquake, with no interruption to gas supplies.

GROWTH THROUGH THE CREATION OF SHARED VALUE
SPECIAL FEATURE 2:
THREE INITIATIVES FOR SECURITY, SAFETY, AND RELIABILITY

Tokyo Gas Supply Control Center
The Supply Control Center monitors and controls gas supply
around the clock, 365 days a year. Our own wireless communication network links the Supply Control Center with the LNGterminals and governor stations. In case of emergency, theCenter can quickly gather information and control gas supply.

Gas Meters (Microcomputer-Controlled)
Gas meters are installed in the homes of all of Tokyo
Gas’s 10 million customers to measure the amount ofgas used. When an earthquake measuring five on theJapanese seismic intensity scale of seven is detected,
the task of ensuring safety by shutting off the gas isVent Tower
Vent towers are used to safely release pipeline gas
into the atmosphere depending on the severity ofentrusted to each microcomputer-controlled meter,
which stops the flow of gas.

damage caused by an earthquake. Vent towers arelocated at LNG terminals and governor stations.

Low-Pressure Pipelines
After gas pressure has been reduced at district governors, our network of more than 45,000-km lowpressure pipelines delivers the gas to homes,offices, stores, and other facilities. Tokyo Gas issteadily switching to the use of polyethylene
pipelines, which offer superior durability, to increase
the earthquake resistance of low-pressure pipelines.

Disaster Prevention Blocks
Low-pressure pipelines are divided into approximately
140 large district blocks. If a block sustains serious damage, gas supply to pipes in that particular block can be

Gas Holder

District Governors (Pressure Regulators)

A gas holder is a spherical container made from high-strength

District governors reduce the pressure of gas transferred throughsteel plates. It stores gas during the day to meet the demand

medium-pressure pipelines, then sends it on through low-pres-fluctuation between day and night. A gas holder can withstandsure pipelines. All district governors are equipped witha strong earthquake such as the Great Hanshin-Awaji

earthquake sensors. When a sensor detects an earthquake

Earthquake. An ignition source will not ignite or explode whenmeasuring lower six on the Japanese seismic intensity scale ofplaced in a gas holder that contains no air.

seven, the district governor automatically shuts off gas supply.

Earthquake Sensors (Seismometers)
Governor Stations

A seismometer detects the seismic intensity felt by a building during

Governor stations are facilities that adjust gas pressure. The

an earthquake. Seismometers are linked to the automatic shut-off sys-pressure of gas sent from a terminal is reduced at a governor

tem at the nearest district governor so that supply can be immediately

station before it is delivered to a medium-pressure pipeline.

shut off when seismic intensity reaches a predetermined level.

Medium-Pressure Pipelines
After gas pressure has been reduced at governor stations, it is sent to district governors located in each area via medium-pressure pipelines. As is the case withhigh-pressure pipelines, most of these pipelines are buried below ground. TheyTOKYO GAS ANNUAL REPORT 2011

shut off without affecting supply to other blocks.

are made by welding strong steel pipes together and are designed to withstandearthquakes on a scale similar to the Great Hanshin-Awaji Earthquake.

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GROWTH THROUGH THE CREATION OF SHARED VALUE
SPECIAL FEATURE 2:
THREE INITIATIVES FOR SECURITY, SAFETY, AND RELIABILITY

2

EMERGENCY
MEASURES

All Major Facilities Have Emergency Shutoff Systems.
The delivery of gas must be stopped immediately inthe unlikely event of a break in a gas pipeline.
Therefore, all supply facilities, such as terminals andThe medium-pressure pipeline
network is divided into 15
medium-pressure blocks

gas holders, as well as large buildings and facilities,

The low-pressure pipeline
network is divided into around
140 low-pressure blocks

including underground malls and high-rise buildings,
are equipped with an emergency shutoff system.
There are two types of emergency shutoff systems.
There is the emergency shutoff valve, which can beoperated remotely, and the automatic shutoff system, which is connected to seismometers. These

Disaster Prevention Blocks

systems are used to ensure safety in a number ofother situations besides an earthquake. They also

it first ensures that it can do so safely. In such situa-safely release gas inside pipelines into the atmos-tions, medium-pressure and low-pressure pipeline

phere via vent towers installed in major facilities if

networks are divided into a number of “blocks.” Supply

required due to the severity of damage.

is shut off to blocks that have sustained considerable
damage, while blocks with no damage or relatively

Our System Prevents Secondary Damage andminor damage continue to receive gas supplies.

Minimizes the Area in Which Supply Is Interrupted.

Because the system is configured so that gas is

In a major earthquake, in order to prevent secondary

not supplied from one block to another, gas supply

damage, it is necessary to stop the supply of gas tocan be stopped quickly without affecting otherareas where gas facilities and equipment have sus-

blocks by shutting down the supply sources, suchtained damage. However, even in the event of anas district governors and governor stations, within aemergency, Tokyo Gas considers it important to con-particular block. Even during the recent earthquake,tinue supplying gas wherever possible so as not toTokyo Gas’s earthquake damage prevention systemcause inconvenience to customers, although of course

functioned properly.

Our SUPREME* System Controls Low-pressure
Gas Supply
Under the SUPREME system, we have installed
earthquake sensors in all of our nearly 4,000 district
governors, which supply low-pressure gas. WithTOKYO GAS ANNUAL REPORT 2011

approximately one sensor per square kilometer, thislevel of installation density is unparalleled on a global scale. The system quickly and effectively helps
prevent secondary damage by estimating damage
from the distribution of the size of tremors. The system then collects fire warnings information andremotely shuts off supply to blocks assumed tohave sustained considerable damage.
* Super-dense Real-time Monitoring of Earthquakes

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Earthquake Sensor(Seismometers)

Distribution of Earthquake Sensors(Red dots: Tokyo Gas seismometers
Blue frameworks: Disaster prevention blocks)

GROWTH THROUGH THE CREATION OF SHARED VALUE
SPECIAL FEATURE 2:
THREE INITIATIVES FOR SECURITY, SAFETY, AND RELIABILITY

3

RESTORATIONMEASURES

Meticulous Preparedness Ensures Resumption

are resumed. Using this equipment, we can supplyof Supply as soon as Possible.

gas continuously to high-priority customers, such as

In areas where the supply of gas has been shut

hospitals, welfare facilities, and evacuation centers.

down, we must resume service as quickly as possible to minimize the inconvenience to our customers.

Gas Companies Nationwide Join Forces in

We have equipment, materials, and systems readyTimes of Disaster.

for deployment at a moment’s notice in the event ofThere are as many as 200 companies supplying citya disaster. This enables Tokyo Gas to draw on thegas throughout Japan. When an earthquake or othercombined strengths of the Group to begin repairs

kind of disaster causing serious damage occurs, theseand restoring services.

companies come together under the auspices of theJapan Gas Association to help efforts to resume gas

Mobile Gas Generation Equipment Temporarily

supply as soon as possible. In the recent disaster,

Enables Supply to Hospitals and Evacuation Centers.

teams from Tokyo Gas andTokyo Gas has portable

other companies swunggas generation equipment

into action to provide assis-that it uses to provide tem-tance primarily in theporary gas supplies until

Tohoku region.

normal supplies in the area

Inspecting a Customer’s Gas Meter

Repairing a Low-pressure Supply PipeTOKYO GAS ANNUAL REPORT 2011

On March 11, 2011, the Great East Japan Earthquake occurred. The earthquake’s
epicenter was located in the Pacific Ocean off the Sanriku area of northeastern
Honshu. Here, we explain this earthquake’s impact on our customers, and our
response and other initiatives.
Although the Great East Japan Earthquake was the greatest earthquake ever recorded in Japan, Tokyo Gas was fortunate in that none of its terminals, pipelines, or otherfacilities sustained major damage. However, we shut off gas supplies to 30,596 customers, including the entire area of Hitachi City, in order to ensure their safety.
Directly after the earthquake, the Company established an Emergency Response
Organization, with President Tsuyoshi Okamoto as its leader, and immediately
launched its response.
When restoring services to areas where gas supply has been stopped, it is important to prevent secondary damage from occurring once service is resumed.
Consequently, Tokyo Gas has to check pipes supplying each customer and gas
appliances one by one to ascertain whether or not there has been any damage.
Up to 711 employees, including those from Tokyo Gas, installation companies,
Tokyo Gas LIFEVAL, and other Group members, took part in the restoration ofservices in order to minimize the inconvenience to our customers as quickly as
possible and reduce their anxiety. On the first day, March 13, gas supply was
restored to hospitals, which had top priority. In the end, gas services had been
reinstated to all customers in about one week.
One reason we were able to restore services ahead of schedule was that we had
begun using methods for rapid restoration that had been provisionally implemented from October 2010. We developed these methods by applying pastexperiences in restoring gas supplies following earthquakes. We first devised anumber of restoration methods suitable for a variety of damage scenarios. We
then selected the most practical of these for implementation.
Going forward, even if a major earthquake should occur, we will work hard tosecure the safety of customers and minimize inconvenience. By adopting thisapproach, we will endeavor to establish and maintain trust in gas as a form of energy, as well as in Tokyo Gas itself.

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