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Guidelines for Safe Operations on Board- To prevent oxygen deficiency and gas intoxication accidents during operations in enclosed spaces -The Maritime Human Resource Institute, Japan

About These Guidelines
Oxygen deficiency and hazardous gas intoxication
accidents during work in coasting or ocean-goingvessels take people's precious lives. These guidelines
describe important points to prevent such tragic
casualties, providing cases based on actual accidents
and safety measures using examples.
These guidelines do not necessarily provide
measures that must absolutely be taken to prevent
accidents, but give recommendations as effective
safety measures. Make use of them to learn safetyknowledge, for example, by using them in safety
and health committee meetings on board.
People forget and make mistakes. So read theseguidelines repeatedly for your own safety and thatof your colleagues.

iContents
Chapter 1

Basic Knowledge to Prevent Accidents
in Enclosed Spaces ............................................ 1
1-1 Risks in enclosed spaces .................................. 2
1-2 Points for safety measures to prevent oxygen
deficiency and gas intoxication accidents ..... 3

		
Chapter 2

Learn from Past Accidents ............................. 5
2-1 A gas mask was used in case ofoxygen depletion ............................................ 6		

2-2 Ventilation in the tank was insufficient ........ 8
2-3 Hazardous chemical gas was not tested ...... 10
Chapter 3

Measures to Prevent Accidents ................... 13
3-1 Adequate ventilation ..................................... 14
3-2 Sufficient preparation for safe entry ............ 18
3-3 Proper testing ................................................. 22
3-4 Ensuring the safety of workers ..................... 26
3-5 Correct use of respiratory
protective equipment .................................... 30

		

3-6 Performing rescue activities calmly .............. 34
Summary ...................................................................................... 38ii

What is an Accident ?
Marine accidents never stop
Numerous accidents are reported to us each year. You think "It will
never happen to me," don't you? Well, everybody thinks so. But infact, oxygen deficiency or gas intoxication accidents on board occur
almost every year. Do you know why?

Why does an accident occur ?
Most accidents occur when there is a defective part of someequipment or facilities, or a mistake occurs in an operation or task.
It is never due to occasional "bad luck." Oxygen and hazardous gas
are invisible, while their status changes depending on environmental
conditions, and that makes their risk difficult to notice.

Background risk
As you know, to ensure safety in an enclosed space, it is extremely
important that you ventilate the area and measure necessary
values, as well as use respiratory protective equipment as necessary.
Perhaps you are thinking, even if you haven’t said it yet, "it will
be same as usual," "I’ll get it over with quickly," or "it’s too muchbother," aren't you ? Well, an accident always has a root cause.

A "remote chance" still has a possibility !
Usually we are not afraid of an accident because we expect itwill never happen. If an accident occurs, however, we often use"unexpected" or "don't believe" or other words, but it's too late.
To avoid such a situation, we must understand the risks and takepreventive measures, as well as prepare for an accident should
it occur. In other words, we should take necessary safety anddisaster-preventive measures.

iii

Chapter 1

Basic Knowledge to Prevent
Accidents in Enclosed Spaces

Various risks lurk in vessels. Factors peculiar to vessels, such as severe
environments, and vessel structures/equipment that can endure suchenvironments, as well as dangerous cargos, will all lead to various risks.
One of them is a watertight structure, which causes a lot of accidents in
enclosed spaces.
In this chapter, we will give an overview of major risks in enclosed
spaces, as well as cautions for and preventive measures against suchrisks.

1

Chapter 1 Basic Knowledge to Prevent Accidents in Enclosed Spaces

1-1

Risks in enclosed spaces

An enclosed space refers to an area isolated from the outside and not always
ventilated, such as cargo spaces, tanks, pump rooms, chain lockers, a zone such as
double bottoms, or unventilated stores or passages leading to enclosed spaces.
Such areas do not have an ordinary atmosphere due to various reasons, andtherefore involve the following risks almost without exception.

1

Immediate oxygen
deficiency

When air contains insufficient oxygen, a man could die
immediately, because oxygen in the blood becomesinsufficient. Perform sufficient ventilation and testing (thenormal oxygen concentration is 20.9%).
P4: Column 1

2

Variousintoxications

Hazardous gas has diverse toxic effects on blood, nerves
and organs. Certain types of gas are harmful even when
the concentration is 0.0001% (1ppm) or less. Perform
sufficient ventilation and testing when working to ensurethat the concentration does not exceed the threshold limit
value (TLV).
P4: Column 2

3

Explosion of
combustible gas

Combustible gas such as petroleum could explode atcertain oxygen and gas concentrations, when an ignition
source is present. To prevent explosion, ensure that thegas concentration does not exceed one-tenth of the lower
explosive limit (10% LEL), or 1% LEL to secure work safety
in an enclosed space.
P4: Column 3

Suffocation

Oxygen deficiency
in air

Enclosed space2

ExplosionIntoxication
Hazardous gas

Combustible gas

Chapter 1 Basic Knowledge to Prevent Accidents in Enclosed Spaces

1-2

Points for safety measures to prevent oxygen
deficiency and gas intoxication accidents

The following efforts are essential to prevent oxygen deficiency and gas
intoxication accidents.

1 Adequate ventilation
Never fail to perform mechanical ventilation before work. The effect will change,
so take enough time to ventilate as a pre-work operation, and continue ventilation
during work.

2 Sufficient preparation for safe entry
The level of oxygen deficiency substantially changes depending on the situation in
enclosed spaces. Moreover, the effects of hazardous gas on human bodies largely
differ depending on the type of gas. Therefore, thoroughly check the risk ofhazardous gas at the pre-work meeting.

3 Proper testing
Never fail to do testing without mistakes so as not to overlook a dangerous conditionin enclosed spaces.

4 Ensuring the safety of workers
Workpreparation

An attendant must keep checking
the safety of a worker, because theworker may faint during the work.

5 Correct use of respiratory
protective equipment
Since respiratory protective equipment
is the last preventive measure, always
check them and never make a mistakein using them.

6 Performing rescue
activities calmly
A victim tends to panic, resulting inoutrageous actions. In such a casegather all staff together to handle thesituation.

Testing

Ventilation
Worksafety check

Respiratory
protective
equipment/emergency
callRescue3

Chapter 1 Basic Knowledge to Prevent Accidents in Enclosed Spaces

Column 1

Oxygen in the blood changes with the oxygen concentration in air.
Oxygenconcentration

Work
Normal

20.9%

Caution

18% or more

Prohibited

Effects, etc.
Normal condition
Safety limit, mechanicalventilation required

16%

Headache, nausea

12%

Dizziness, muscle weakness

8%

Fainting, unconsciousness,
death within 7-8 minutes

6%

Immediate coma,
respiratory standstill, death• If the oxygen concentration in inhaled
air decreases, the oxygen absorbed
into the blood will also drop, resultingin oxygen deficiency.
• In a s e v ere ox yg en d e ficienc yenvironment, in-blood oxygen isexhaled to the air. Unlike breath
holding which gradually suffocates,
severe oxygen deficiency immediately
makes a person "faint," just as if they
were choked in Judo.

Column 2

The higher the concentration of hazardous materials, the heavier the
impairment.
Limit ofcompensation
process

Death

LethalInfluence

Permanent
impairment

DiseaseNormal function

Impairment

RecoveryHomeostatic function
Healthy
Allowable concentration
Normal regulation Compensation Breakdown

Destruction

Hazardous material concentration (log scale)• Hazardous materials of highconcentration will lead to humandeath or after-effects that last forlifetime.
• The concentration at a worksite shallbe managed within the threshold
limit value, which means limiting theconcentration so that it does nothave adverse effects on the health ofworkers.

Column 3

Combustible gas ignites when three factors -oxygen, gas, and an
ignition source- come together in burning conditions. In enclosed
spaces, the temperature and pressure increase at an accelerated pace,causing an explosion of combustible gas.
FlamepropagationHigh
temperatureHighpressure4• In normal air, the mixing ratio ofoxygen and gas when burning fallsb et we en the lower and upp er
explosion limits.
• Gas with a low ignition point tends toeasily ignite, and its flame propagates
rapidly, generating huge energy.

Chapter 2

Learn from Past Accidents

Quite a lot of accidents have occurred on board to date. We should
learn lessons from such tragic accidents to prevent their recurrence. It is
the only way for us to make the most of the precious lives of victims lostin past accidents.
This chapter describes three cases based on past accidents. Let's learn
about the background situations and causes for each case, and consider
preventive measures against them.

P12: Column 4

5

Chapter 2 Lessons from Past Accidents

2-1

A gas mask was used in case of oxygen
depletion
Case

When the chief officer entered the tank to attach a drain plug, he fainted and fell
over. The bosun thought it was a crisis, immediately put on a gas mask, and entered
the tank to rescue him. But the bosun also felt dizzy, fell down, and died.

Background Factors
1. Inert gas was filled inside the tank to prevent explosion.
2. The chief officer and the bosun were coworkers who had known each other along time, and were really good friends like brothers.
3. The company was equipped with gas masks, but had not explained how to use
them.

6

Chapter 2 Lessons from Past Accidents

Causes
1. The oxygen concentration was not tested before entering the tank.
2. The bosun was too upset about the accident of a comrade to call rescue staff.
3. The bosun was not familiar with the use of a gas mask.

Preventive Measures
1. Crew members must make it a habit to take along an oxygen meter every time
when entering an enclosed space.
2. The company must provide crew members with training useful for emergency.
3. Crew members must be trained to never use a gas mask but to use self-contained
breathing apparatus, when the oxygen and gas conditions are unknown.

7

Chapter 2 Lessons from Past Accidents

2-2

Ventilation in the tank was insufficient
Case

After finishing unloading of gasoline, the vessel went to sea while performing
ventilation cleaning. When crew members entered the tank to wipe off residualliquid, the master ordered the work be suspended because the tank was filled witha strong odor. But an officer, who had not joined in the cleaning work at that time,
did not follow the master's instruction, and entered the tank alone to wipe off theliquid while other members were having a rest. As he did not come out from thetank, another officer on duty noticed something was wrong, and let crew members
rescue the officer inside the tank. After an emergency docking at the nearest port,
the officer was hospitalized, but died later.

Background Factors
1. It was raining, and the temperature was low.
2. The officer intended to be nice to his colleagues because he did not join in theinitial tank cleaning work when other members did.
3. Gasoline contains toxic substances such as benzene and toluene.

8

Chapter 2 Lessons from Past Accidents

Causes
1. Mechanical ventilation was carried out in enclosed spaces, but its efficiency
deteriorated due to the temperature and humidity at that time.
2. The officer did not follow the master's instruction, but entered the tank alone
to work at his own judgment, trying to be nice to colleagues.
3. The company did provide safety training, but mainly on ignition and explosion. It
did not give training on toxicity.

Preventive Measures
1. The required ventilation time changes depending on the type of cargo orenvironmental conditions. So crew members must take enough time toconfirm the safety of the space by testing gas concentrations, while continuing
ventilation during work.
2. The master must thoroughly instruct crew members to keep out of an enclosed
space before confirming safety, and a worker must obtain the master's
permission to enter such an area.
3. The company must periodically visit vessels, provide training and instruction
on dangerous goods, and confirm the implementation status of operating
standards to keep crew members thoroughly informed about them.

9Chapter 2 Lessons from Past Accidents

2-3

Hazardous chemical gas was not tested
Case

After unloading chloroform, the liquid leaked from the sealing at the pump axis,
which spread over the pump room floor. A worker wiped off the liquid, andcontinued maintenance work. Later he felt bad, but still continued the work. Afterdinner, he became sick, and went to a hospital. He was diagnosed as intoxicatedand hospitalized, but died 2 days later.

Background Factors
1. Liquid had often leaked in the pump room due to a defect of the pump axis
sealing.
2. Detection and protective equipment were checked only at vessel inspection.
3. Chloroform not only has acute adverse effects on nerves, but also delayedadverse effects on liver and kidney functions.

10Chapter 2 Lessons from Past Accidents

Causes
1. The pump axis sealing had not been repaired since the parts had not beendelivered.
2. Testing was not carried out, since there were no gas-detecting tubes ofanalysers. Moreover, protective equipment was not used.
3. The worker did not know the hazardous effects of the liquid. Therefore, hecontinued working alone even after he felt sick.

Preventive Measures
1. Defects of equipment or devices must be promptly repaired.
2. The company must provide vessels with easy-to-use analysers to test hazardous
gas concentrations at a worksite.
3. Workers must immediately stop working if they feel sick, and promptly seek
medical advice.

11

Chapter 2 Lessons from Past Accidents

Column 4

To prevent recurrence of accidents, the International Maritime
Organization (IMO) established guidelines for the investigation of
accidents based on the following two aspects in 1999.
Accidents occur due to a variety of factors. The SHEL
model
in the following figure illustrates the relationshipSHEL
between the worker (L on the middle), relevant parties (Lon the bottom), procedure/method (S on the left), facilities, materials andequipment (H on the top), and working environment (E on the right).
• SHEL particularly focuses on defects in therelationship between the worker and otherfactors.
• Link in SHEL
Since individual workers are interrelated,
SHEL is a link between individual workers.

In an organization, decision makers, site managers, andworkers all have their responsibilities; and workers have
responsibilities in their work directly related to an accident,
as well as for preventive measures should an accident occur. Multiple
safeguard is a way to prevent problems (holes in the following figure) fromoccurring at any level, thereby promoting safety.

Multiplesafeguard

maSiteDecnag
ers
maision
ker
s

Wo
rke
rs

Wo
rk

Pre
meventiv
asu e
res

Not
ices

t
ec ng
ef ti
D or
p
re

Hybrid model

12

Acc
ide
nt

• For example, when a problem remains at thesite manager level, if a worker notices andeliminates it, an accident will be prevented.
• The Defect Reporting System aims to correctsuch a problem.

Combination of "SHEL" and "multiple safeguard"Chapter 3

Measures to Prevent Accidents

There are quite a lot of onboard operations as a result of which a
mistake or an error often occurs, leading to an accident. In the following
pages, the work flows of onboard
operations are organized, and tips forindividual jobs are provided. The details
are classified and assigned different
colors of tags as follows. Refer to thecorresponding section number and color
tag to easily access a desired page.

In normal
operations

3-1

Adequate ventilation• Preparation for ventilation• Operation

3-2

Sufficient preparation
for safe entry• Risks, materials and equipment• Pre-work meeting

3-3Proper testing• Oxygen concentration testing• Gas testing/detection

3-4

Ensuring the safetyof workers• Permission to enter/attendant• Post-work meeting

3-5

Correct use of respiratory • Self-contained breathing apparatus
protective equipment• Gas mask

3-6

Performing rescue
activities calmly

In abnormalcases• Initial action and preparation• Training and rescue activities

13

Chapter 3 Measures to Prevent Accidents

3-1

Adequate ventilation

Never fail to perform mechanical ventilation
1 Ventilation efficiency is low at first
Air from the ventilator mixes with air inside the tank, and is discharged little bylittle. Thus, the ventilation effect gradually increases.

2 The amount of air from the ventilator varies
The amount of air from the ventilator varies depending on obstacles in the inlet
or exhaust vent, as well as the length or bending of pipes or ducts.

3 The gas concentration varies from place to place
Air from the vent does not easily reach the corners or the bottom, as a resultof which, the gas concentration varies from place to place; gas heavier than air
tends to accumulate at the bottom, while gas lighter than air rises to the ceiling.

Check the conditionof connectionsand valves.

Hazardous gas mixed
with blowing air is
gradually discharged.

4/10
3/10

Tank

2/10
1/10
0/10
Gas is retained.

14

Pump
room

Chapter 3 Measures to Prevent Accidents

Step 1 Prepare for ventilation

Normal ventilation facilitates air intake, blow, and exhaust efficiently.
To ventilate the tank, connect blower pipes to the cargo lines after cleaning, andadjust each valve to obtain an appropriate amount of air in the tank.

Tips!
• Check for any residual liquid in the cargo line.
• Never fail to connect and disconnect ventilation hoses.
• Adjust valves for ensuring well-balanced ventilation in all tanks.

15

Chapter 3 Measures to Prevent Accidents

Ventilator operations
1 When using the ventilator, the drop in concentration
slowsdown as the ventilation time passes
Since blowing air is first mixed with air in an enclosed space and then discharged,
the gas concentration decreases with ventilation. The discharged amount ofgas decreases accordingly, resulting in a gradual decrease in the change ofconcentration.

2 The drop in concentration slows down due toevaporation of residual liquid
Cleaning water or residual liquid tends to remain at the corners and dents in thetank. Liquid with low volatility or high viscosity, in particular, takes a long time tofinish evaporating.

3 The drop in concentration varies with temperatureand humidity
At a low temperature or a high humidity, water or liquid evaporate slowly, justlike at the laundry, which requires more time than usual to ventilate.

4 Some substances may temporarily lead to a highgas concentration
For some chemical products diluted in water, even with small volatility, the gas
concentration may sharply rise when chemicals evaporate just before the waterdries up.

g

Gas concentration

16

Oxy

on

rati

cent

on
en c

3: Effect fr
om lo
2: E
w tem
ffec
perat
t fro
1: D
ure/h
me
rop
igh hu
vap
midit
in c
ora
y
onc
tion
ent
rati
on
slow
ing
dow
n
Ventilation timeChapter 3 Measures to Prevent Accidents

Step 2 Ventilator operations

Ventilator operations must take enough time, because the ventilation effect, which
is usually determined by the tank capacity, air volume or ventilation time, varies
depending on the type of cargo or environmental conditions.

Tips!
• On the blackboard or the like, clearly indicate the time when and bywhom the start switch of the ventilator was turned on, together witha KEEP OUT notice.
• Take a longer ventilation time than usual at a low temperature or ahigh humidity, because the ventilation efficiency decreases under suchconditions.
• Take a longer ventilation time than usual for liquid cargo with low
volatility or high viscosity, because such cargo tends to remain in
dents, etc.
• Stop the ventilator 10 minutes before testing, and resume ventilation
after testing.

17

Chapter 3 Measures to Prevent Accidents

3-2

Sufficient preparation for safe entry

Understanding the risk of oxygen deficiency
and hazardous materials
1 Understanding the risk of oxygen deficiency• Oxygen deficiency will often cause instant fainting followed by death.
• In an enclosed space, oxidation of rust or cargo, aspiration of sludge or liquid cargo, or
evaporation of residual liquid will all spontaneously lead to oxygen deficiency.
• A tank injected with inert gas has an oxygen deficiency.

2 Understanding the risk of hazardous materials in the
Safety Data Sheet (SDS)• Hazardous effects mean irritation and burn resulting from contact with liquid,
as well as acute and delayed adverse effects from gas inhalation.
• The threshold limit value (TLV) means the limit of concentration which does
not have adverse effects on health in daily work.

3 Understanding appropriate testing equipment• Use an oxygen analyser for oxygen concentration testing (normally 20.9%).
• For hazardous gas testing, check if a volatile organic compound measuring
instrument can be used.

4 Understanding appropriate protective equipment• To prevent contact, use protective
goggles, protective suits, protective
gloves, or protective boots.
• To prevent oxygen deficiency andinhaling high concentration gas, use
self-contained breathing apparatus.
• For hazardous gas, use a gas mask
only when ox ygen deficienc ydoes not occur, and the type andconcentration of gas are identified.

18

Chapter 3 Measures to Prevent Accidents

Step 1 Checking SDS

Check SDS for materials to be used.

Submit the checked SDS.

The degree of hazard greatly varies depending on the type of hazardous
material. Therefore, it is important to check the SDS.

Tips!
• Even when handing liquid cargo that was previously handled, checkthe SDS each time due to the possibility of misunderstanding or poor
memory.
• Accurately match the name of the liquid cargo to the substance in the
SDS to confirm the degree of hazard.
• When a substance name is not clear from the product name, consult
the company.

19

Chapter 3 Measures to Prevent Accidents

Pre-work meeting
1 Never fail to hold a pre-work meeting• During work, a necessary process might be omitted if each person’s duty is notclearly defined.
• Never start work with a lack of understanding. When safety is confirmed, an"ENTRY PERMIT" must be explicitly posted.

2 Prepare necessary equipment/materials• Preparations will progress smoothly without mistakes if "who handles what" isdecided.
• Make analysers, protective equipment,
and rescue materials /equipment
available for immediate use.

20

Chapter 3 Measures to Prevent Accidents

Step 2 Pre-work preparation of materials and equipment
and pre-work meeting

Prepare necessary materials and equipment, and confirm the work flow in a prework meeting.

Tips!
• At the meeting, all seafarers involved in the work must confirm thework plan, while a responsible person must instruct personnel on theirroles.
• Confirm the ventilation start and elapsed time, and continue
ventilation during work.
• Place necessary materials and equipment, such as analysers orprotective equipment, at a location near the entrance to a worksite.

21

Chapter 3 Measures to Prevent Accidents

3-3

Proper testing

Oxygen concentration testing
1 Never fail to carry out testing• If a work area is in oxygen deficiency, it often causes instant fainting, followed
by death. The time to reach oxygen deficiency status varies depending on
various conditions. So never rely on past experience, nor fail to carry out
testing.
• Testing must be carried out from the top of the tank, in order from top,
center, and bottom of the tank. Moreover, after confirming safety, enter thetank, and test oxygen at the working position by extending the tip of thesensor.

2 Oxygen analyser• Use an oxygen analyser of which the reliability has been confirmed by adetection sensor still within its operating lifetime.
• In an enclosed space, hydrogen sulfide from sludge or carbon monoxide fromburning is easily generated, which is not detected by oxygen testing. Use gas
detectors in such cases (See "Complex gas monitor" on page 25).

22

Chapter 3 Measures to Prevent Accidents

Step 1 Oxygen concentration testing

Portable type (example)
RIKEN KEIKI Co., Ltd.

A portable oxygen analyser can carry out testing at a remote position by extending
tip of the sensor. A personal monitor can be taken along during the work, andcarry out testing on the spot.

Tips!
• Turn on the oxygen content analyser, and check if the indicator value
is 20.9% in fresh outside air. Misreading the indicator value may be
dangerous.
• While confirming safety, extend the tip of the sensor to the working
position.

23

Chapter 3 Measures to Prevent Accidents

Gas testing/detection
1 Hazardous gas testing• Hazardous gas is invisible, and has adverse effects through inhalation. Somehazardous gases have no odor, or a slight odor that workers easily get used to.
Never judge if gas is present or not by smelling.
• A hazardous gas detector indicates ultra-low concentration (in ppm:
1ppm=0.0001%) through physical/chemical reactions with coloring reagentsin glass tubes (detection tube-type analyser), or ultraviolet ray emission lights(volatile organic compound measuring instrument).

2 Combustible gas detection• Combustible gas such as in oils may explode even with a concentration within
the explosion limit. Check that there is no risk of explosion.
• A combustible gas detector indicates the risk of combustion as a lower
explosive limit (LEL: 1 to a few percent for many substances) rather than a gas
concentration itself.

3 Two test values are different things
When doing any testing, test the top, center, and bottom of the space as wellas the working position, while confirming safety. Do not confuse hazardous gas
testing with combustible gas detection: they are totally different in purpose andmethod. They cannot be used interchangeably.

24Chapter 3 Measures to Prevent Accidents

Step 2 Hazardous gas testing and combustible gas detection
Typical hazardous gas detector
Volatile organic compound
measuring instruments

Detection tube-typemonitorTypical combustible
gas monitor

Tapered nozzle

Buzzer

Detector
tube

RIKEN KEIKI Co., Ltd.

Menu
Mode switch
Power switch

RIKEN KEIKI Co., Ltd.

SHINOHARA ELECTRIC Co., LTD.

Gas
sampling
pump

GASTEC Corporation

Typical complex
gas monitor

RIKEN KEIKI Co., Ltd.

Most chemical products can be tested by two types of instruments: the volatileorganic compound measuring instrument on the left, and a detection tube-typemonitor*. To prevent explosion, use the combustible gas detector (at top right). It isalso useful to use a complex gas monitor (at bottom right) which integrates oxygen,hydrogen sulfide, and carbon monoxide sensors, in addition to a combustible gas
detector.
*Some instruments have their own name, such as "Kitagawa Gas Detector Tube System" or "Dräger Tube."

Tips!
<Volatile organic compound measuring instruments>• Turn on the equipment, and confirm the results of automatic stand-by checking.
• Select a target substance from the tested gas selection menu. If awrong substance is selected, the indication value will substantiallydiffer, which may lead to a certain risk.
• Confirm a zero indication in fresh air.

25

Chapter 3 Measures to Prevent Accidents

3-4

Ensuring the safety of workers

Points during work
1 Never enter an enclosed space without records and permission• Prior to entering an enclosed space, confirm safety, and test and record
oxygen and gas concentrations.
• Obtain permission to enter the enclosed space from a responsible person andapproval to enter from the workers doing the work, and record them.
• To observe the above points without fail, use a checklist.

2 Supervise workers at work
• An attendant must stand outside, and keep talking to the workers at work to
consistently check on their safety.
• A responsible person shall carry out concentration testing as necessary.
• Always have rescue materials and equipment ready for use just in case.

26

Chapter 3 Measures to Prevent Accidents

Step 1 Supervise the work

An attendant must confirm safety, record the permission to enter, and always
supervise the workers during the work.

Tips!
• A responsible person must check on safety including oxygen deficiency,
give permission to enter, and record it.
• An attendant must stand at a position from where the lower levels
and the tank bottom can be seen, and should frequently talk to theworkers at work, directly or by using a transceiver, at regular intervals
to check on their safety.
• If the attendant feels anything is wrong, even very minor, immediately
make the workers at work evacuate the worksite.

27

Chapter 3 Measures to Prevent Accidents

Points after work
1 A responsible person must check the safety ofworkers at work, and record the results
There is a risk of placing a manhole cover while a worker remains in the tank,leaving him alone.

2 A responsible person must takesafety measures after work
Never fail to close the entrance of the enclosed
space, and take measures to prohibit entering.

3 A responsible person must makeused materials and equipment
ready for use next time
Clean, check for abnormality, and store them.

28

Chapter 3 Measures to Prevent Accidents

Step 2 Work completion

After the work, a responsible person must check the safety of the workers, andclean and check materials and equipment before storage to make them ready foruse next time.

Tips!
• A responsible person must gather all workers involved in the work to
the meeting, and check the safety of all of them.
• A responsible person must check working conditions, the status ofdrain plugs, etc.
• A responsible person must maintain and check materials andequipment before storage to make them ready for use next time.

29

Chapter 3 Measures to Prevent Accidents

3-5

Correct use of respiratory protective equipment

Self-contained breathing apparatus(for air supply in case of oxygen deficiency or dangerous hazardous gas environment)

1 Apparatus constitution
The apparatus consists of a high pressure gas cylinder, pressure reducing
valve, cylinder valve, pressure indicator, facemask, attaching belt and frame. It
decompresses a certain amount of air, and ventilates it to the facemask.

2 Precautions• Firmly tighten the belt, and put on the facemask to achieve a fit for preventing
an air leak.
• The amount of air in the gas cylinder is limited; it can be used only for a shorttime if the respiration amount is large.

3 Maintenance of apparatus
In a vessel, check the gas cylinder air pressure, deterioration of rubber andother parts, and leak at the hose connection. On land, periodically undergo the
manufacturer's inspection.

30

Chapter 3 Measures to Prevent Accidents

Step 1 Use of self-contained breathing apparatus

SHIGEMATSU WORKS CO.,LTD.

Thoroughly familiarize yourself with the use of the apparatus, as it will be used incase of emergency.

Tips!
• Check that the gas cylinder air pressure is sufficient before use.
• Train yourself to smoothly fasten a number of belts (to put on theapparatus within one minute).
• After wearing, check that the facemask closely fits the face.
• Use the apparatus cautiously so as not to use air excessively, by
watching the pressure indicator.

31

Chapter 3 Measures to Prevent Accidents

Gas mask (to reduce exposure to hazardous gas)
1 Apparatus constitution
The apparatus consists of a cartridge, facemask, and fastening belt. The
cartridge contains an adsorbent for gas, which generates no oxygen. Adsorbents
for organic gas, acid gas, ammonia gas, and others are currently available, which
are used case by case, depending on the target gas.

2 Three conditions for use
1. Do not use in oxygen deficiency conditions (20.9% oxygen by volume byoxygen content meter).
2. Identify the hazardous gas, and make sure no other gas is present.
3. Use a gas mask with a cartridge appropriate for the target hazardous gas inan area with a limited concentration for a limited duration of time.

3 Management of cartridge• The adsorption breakthrough curve (in the following figure) indicates the limit
of usable time of the cartridge.
• The cartridge requires sealed storage. Even if sealed, the cartridge will
deteriorate. Replace a deteriorated cartridge promptly with a new one.

4 When feeling sickThe capacity of the cartridge has a limit
Gas concentration

If you detect an odor duringuse, or feel sick, immediately
stop working, go outsidewhere you can breathe, andthen remove the mask.

Danger

Gas concentration
during work

Caution
SafetyTime towork safely

32

Time used
Time never toexceed(breakthrough time)Chapter 3 Measures to Prevent Accidents

Step 2 Use of gas mask
Examples of gas masks
Detached typeCompact direct-connected type

Direct-connected type

Test oxygen and gas concentrations first.

SHIGEMATSU WORKS CO.,LTD.

Misuse of gas masks has often led to death. Obtain permission from a responsible
person, and use the mask correctly.
(Note) Misuse of gas masks includes: using the mask in oxygen deficiency conditions, mismatch of the typeof cartridge to the target gas, and using the cartridge after exceeding the usage limit.

Tips!
• A responsible person must confirm environmental conditions todetermine if a gas mask can be used.
• Attach a cartridge which is appropriate for the target gas and hasenough time left for use.
• Wear it securely so that the facemask closely fits the face.

33

Chapter 3 Measures to Prevent Accidents

3-6

Performing rescue activities calmlyFirst actions to be undertaken
1 If you find an abnormal condition of a worker at work
• The attendant must not leave the safe place, but instruct the worker toevacuate by himself.
• The attendant must also ask anyone to call a rescue team. Never enter an
enclosed space without safety measures.

2 If a worker becomes unable to move
• The attendant must ask anyone to call a rescue team. Never enter an enclosed
space without safety measures.
• The master or other person must immediately call a Maritime Rescue
Coordination Center (MRCC) without hesitation.
• Check the operation of mechanical ventilation equipment, and intensively
ventilate the tank where the worker is.

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Chapter 3 Measures to Prevent Accidents

Step 1 Training and initial action

For rescue, keep yourself calm, and prepare thoroughly.

Tips!
• The attendant must call crew members in the vessel, while the masteror other person must call for rescue.
• The rescue team must wear self-contained breathing apparatus and aharness.
• Other crew members must set lifting blocks and a rope.

35

Chapter 3 Measures to Prevent Accidents

Rescue is not easy
1 Familiarize yourself through training• Rescue activities must be conducted by a nominated responsible person, andtrained officers and crew.
• When entering an enclosed space, never fail to wear self-contained breathingapparatus.

2 If rescued• Move the victim to a breathable place with fresh air, check breathing andheartbeat, and give artificial respiration or cardiac massage, as necessary.
• If an emergency squad arrives, smoothly and skillfully cooperate with thesquad.

3 When the victim becomes conscious• Seek medical advice even whenthe victim becomes conscious,
because he may have inhaled
substances that can cause
complications at a later time.

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Chapter 3 Measures to Prevent Accidents

Step 2 Rescue activities

To lift the victim, support him so as not to bump the adjacent wall, etc., hold him
securely to prevent falling, and when he is lifted above the manhole, hold him by
his underarms.

Tips!
• Approach the victim, and attach the lifting rope by a trained method.
• Carefully pull the lifting rope, while checking the victim's condition.
• After lifting up, hold him by his underarms to take him to a safe place,and lay him down. Use cardiopulmonary resuscitation methods asnecessary.

37Summary
Key Points
Adequate ventilation

Discuss before the work

Accurate testing

Never enter without permission / supervision

Correctly use protective
equipment

Gather everyone together, and keep
yourself calm in case of abnormality

MessageNow you understand what risks exist on board or in enclosed space, and how toprevent accidents, don't you? However, knowing and doing are two different
things; you may lose your calm or get confused when you face an emergency.
Thoroughly familiarize yourself with preventive measures and rescue activities,
so that you can do them without any difficulty.
Laws stipulate obligations of testing and use of protective equipment whennecessary. Therefore, the company must make necessary equipment asconvenient as possible, and ensure that crew members never fail to use them.
Do enough training on a regular basis, so as to handle any abnormality, if it
occurs, calmly. Losing your calm can lead to secondary accidents.
Such attitudes and practices will
be useful not only for seafarers
themselves, but also for theirfamilies and acquaintances, aswell as for the company. We
hope all of our readers never
have an accident.

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Easy to Understandwith Illustration !!

Guidelines for Safe Operations on Board- To prevent oxygen deficiency and gas intoxication accidents during operations in enclosed spaces First copy of First Edition, published on March 31, 2015
Editor:Special committee for study and research on safety measures useful forcomplying with SOLAS, STCW, or other regulations for dangerous goods
transport vessels, low-ignition point fuel vessels and liquefied hydrogentransport vessels, as well as for preventing accidents.

Cooperating organization: The Association for Promoting Safety and Sanitation for Seafarers
and Japan Maritime Center.
Material provided by:

SHIGEMITSU WORKS CO., LTD., RIKEN KEIKI Co., Ltd,SHINOHARA ELECTRIC Co., LTD., and GASTEC Corporation

Published by:

The Maritime Human Resource Institute, Japan Kaiji Center Building 5F,
4-5 Kojimachi, Chiyoda-ku, TOKYO 102-0083, Japan
TEL: +81-3-3264-3871 FAX: +81-3-3264-3808
URL http://www.mhrij.or.jp/
		
http: //www.maritime-forum.jp/en/©2015 The Maritime Human Resource Institute,Japan.

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The Maritime Human Resource Institute, Japan
http://www.mhrij.or.jp/