Tanker safety guide chemical four edition 2014

The ICS Guide has since become the standard reference work on chemical tanker operations, with subsequent editions taking particular account of the need for chemical tankers to comply with additional IMO regulations to ensure the prevention of pollution. It is recommended that a copy should be carried on board every tanker engaged in the carriage of chemicals by sea.This fourth editi on of the Guide is the result of substantial revision and updating.In response to feedback from users, and in order to improve access to important information, much of the content from the previous edition''''''''s appendices has been incorporated into the main body of the text, while being comp letely redrafted in the interests of improved understanding. The latest Guide reflects the continuing need for guidance on well established industry best practice, but also takes account of more recent developments which have emerged in the chemical trades. In particular, it should be noted that this updated edition addresses IMO''''''''s adoption, in May 2014, of important new SOLAS requirements for the fitting and use of inert gas on board chemical tankers

TANKER SAFETY GUIDE

CHEMICALS

FOURTH EDITION

INTERNATIONAL CHAMBER OF SHIPPING

INTERNATIONAL CHAMBER OF SHIPPING

Established in 1921, the International Ch mber of Shipping (ICS) is the principal international trade association for shipowners, representing the global industry at IMO and the other international bodies that impact on shipping Its membership comprises national shipown rs' associations from 36 countries, covering all sectors and trades and over 80% of the world merchant fleet

While the advice given in this Guide has been developed using the best information available, i t is to be followed

at the users' own risk No responsibility is accepted by Marit ime International Secretar iat Services Limited, or by the International Chamber of Shipping Limited, or by any fi rm, corporat ion or organisation who or which has been in any way concerned with the furnishing of data, the compilation, publication or authorised translation , supply or sale of this guidance, for the accuracy of any information or advice given herein, or any omission herefrom or consequences whatsoever resulting directly or indirectly from use of this Guide, or from compliance with or adoption of guidance contained herein, even i f caused by a failure to exercise reasonable Cilre

INTERNATIONAL CHAMBER OF SHIPPING

FOURTH ED I TION

Publihed by Maritime International Secretariat Services Limited

38 St Mary Axe, London, EC3A 8BH

Tel +44 20 7090 1460

Email p blications@marisec.org

Web www.ics-shipping.org

© Maritime International Secretariat Services Limited 2014

No tra slation of this guide into a foreign language may be made without the express permission of Maritime International Secretaria Services Limited

FOREWORD TO THE FOURTH EDITION

The first edition of the ICS Tanker Safety Guide (Chemicals) was published in 1971 and complemented the

Dangerous Chemicals in Bulk The ICS Guide was developed from a clear demand, from shipping companies and seafarers, for advice on best practice with respect to safety at sea

editions taking particular account of the need for chemical tankers to comply with additional IMO regulations

engaged in the carriage of chemicals by sea

users, and in order to improve access to important information, much of the content from the previous edition's appendices has been incorporated into the main body of the text, while being completely redrafted in the

interests of improved understanding

also takes account of more recent developments which have emerged in the chemical trades In particular, it

should be noted that this updated edition addresses IMO's adoption, in May 2014, of important new SOLAS

requirements for the fitting and use of inert gas on board chemical tankers This followed an in depth IMO

review of tanker safety- in which ICS participated - that has taken the best part of a decade

Earlier editions of this ICS Guide provided advice on the precautions to be taken prior to entering enclosed

spaces and cargo tanks In the intervening years, serio s enclosed space accidents have unfortunately

continued to occur, primarily due to a failure to follow establihed procedures The need for updated and

improved guidance on this most important safety topic has therefore been given even greater emphasis, with

separate chapters dedicated to both enclosed space entry precautions and to the correct use of nitrogen as an inerting medium

A new feature introduced in this edition is the use of yellow coloured text boxes These contain a summary o

information of adjacent text regarding a particular safety issue Although readers should pay particular attention

a comprehensive understanding

Following the example of the previous edition, a model Material Safety Data Sheet (MSDS) has been included to encourage the presentation of data in a standard format This is particularly important with regard to emergency and first aid information, which needs to be readily identifiable and in a common layout When a ship is at sea,

or at a remote terminal, external assistance may not be available, and easily accessible emergency advice is

therefore vital

Emphasis also continues to be given to the importance of ships and terminals completing the Ship/Shore Safety Checklist in advance of conducting any cargo operations in port, with a revised Checklist and full guidance for completion being incorporated as Appendices

Last but not least, particular attention has been given to the best means of instilling an effective safety culture

No Guide of this nature can ever be complete, however much care and effort has gone into its preparation

Comments and suggestions for improvements to the Guide are therefore always welcome, and should be

PURPOSE AND SCOPE

The purpose of this ICS Guide is to provide those serving on ships carrying hazardous and noxious chemicals in bulk with up to date information on recognised good practice in safe and pollution free operations

This Guide is intended for use on ships regulated under MARPOL Annex II (Regulations for the Prevention of Pollution by Noxious Liquid Substances) including oil tankers operating in accordance with Annex II when they are carrying chemical cargoes However, its contents are also relevant inter alia to shipping company managers, cargo interests, training institutes and terminal operators

The Guide is intended to be compatible with the International Safety Guide for Oil Tankers and Terminals (ISGOTI) in order to provide consistent safe advice and also to minimise the increasing burden associated with audits and vetting inspections This Guide is also a companion to the ICS Tanker Safety Guide (Liquefied Gas) The Guide's recommendations cannot cover every possible situation that may be encountered on a chemical

tanker, but they do provide wide general guidance on safe procedures and safe working practices when handling and transporting chemicals in bulk

In the interests of consistent and uniform safe working practices, it is recommended that a copy of this Guide

be kept - and used -on board all chemical tankers Chemical tankers should also have on board ISGOTI, which should be consulted in conjunction with this Guide, especially whenever oil cargoes are carried

The Guide deals primarily with operational matters and good safety practices It does not make

recommendations on the construction or maintenance of chemical carriers or their equipment: such standards are set by IMO, national administrations and classification societies Likewise, the Guide does not address the operation o specific items of equipment or their repair In some cases, however, general reference is ade to

these matters as well as to relevant regula ons

It should be noted that this Guide is not intended to address commercial matters such as tank cleaning

standards, cargo quality maintenance or equipment performance, which (consistent with IMO regulations) may

be determined by industrial practices and the requirements of cargo owners

CONTENTS OF CD ACCOMPANYING THIS GUIDE

The CO accompanying this fourth edition contains the full text of the Guide with a 'search function'

The CO also contains p ntable/amendable versions of most appendices

IMPORTANT NOTE

It is emphasised that this Guide is intended to complement, not supersede, any company safety and

operational guidelines or ship emergency plans, including safety management procedures required by the IMO International Safety Management (ISM) Code It should also be borne in mind that in all cases the advice given may be subject to local or national regulations, and that terminal operators have their own safety procedures which could affect cargo handling operations and the measures to be adopted

in emergencies The Master and all personnel must be aware of and comply with those regulations and procedures Their existence will be highlighted by the use of the Ship/Shore Safety Checklist included in Appendix 3 of this Guide which, together with its guidelines for completion, remains a fundamental part

of establishing safe conditions for transport by sea of chemicals in bulk

ACKNOWLEDGMENTS

This edition of the ICS Tanker Safety Guide (Chemicals) continues the tradition of providing a consolidation of

experience and best operating practice in the chemical tanker industry Its production would not have been

possible without the assistance of those individuals, companies and organisations that have so generously given

their time and expertise to ensure its accuracy in the interests of the safe carriage of chemicals by sea

meetings making sure that the text was both accurate and that it reflects industry best practice - Toralf S0renes

Eitzen Chemical, Per Winther Christensen of the Danish Shipowners' Association and Peter Maasland of Shell

Particular mention is also made of the following industry associations: the Chemical Distribution Institute

(COi), the International Parcel Tankers' Association (IPTA), the International Association of lndependant Tanker

Owners (lntertanko) and the Oil Companies International Marine Forum (OCIMF) These organisations have

kindly provided a 'peer review' of the fourth edition in order to verify that the contents meet the needs of

the wider industry and their advice and comments have been carefully considered in the drafting of this

industry publication

5

CONTENTS

FOREWORD TO THE FOURTH EDITION

PURPOSE AND SCOPE

Density and specific gravity

Volume expansion coefficient

Charge accumulation and relaxation in liquids

Generation of static

Static generation during cargo operations

Static generation during tank cleaning

Static generating portable equipment

Unstable chemicals

Chemicals that react with oxygen

Chemicals that react with water

Reaction o acids w h water

Incompatible chemicals

Reaction with construction materials

1.8 Hazardous Cargo Information 38

1.8.2 Contents of a Material Safety Data Sheet 38

7

3.10.9 Summary of STCW requirements -hours of work and rest 66

3.11 Personal Protective Equipment (PPE) 67

CHAPTER 4 - REGULATORY FRAMEWORK

Regulatory Guidelines

IMO MARPOL Regulations

MARPOL Annex I - Prevention of Pollution by Oil

MARPOL Annex II - Prevention of Pollution by Noxious Liquid Substances

MARPOL Annex VI -Prevention o Air Pollution from Ships

IMO International Code for the Construction and Equipment of

Ships carrying Dangerous Chemicals in Bulk (IBC Code)

Tank types

Summary of IBC Code requirements

lnerting and padding

Damage stability

Inert Gas Requirements for Chemical Carriers

IMO Ballast Water Convention

CHAPTER 5 - SHIP AND EQUIPMENT

Alarms and shutdowns

Air supply to control systems

Liquid level gauges

Overfill detection systems

Pressure indicating devices

Temperature monitoring equipment

Atmosphere Monitoring

General

General recautions

Oxygen analysers

Flammable gas detectors

Toxic gas detectors

Venting Systems and P/V Valves

Vapour Return Systems

Heating and Cooling Systems

Tank Washing Systems

Fixed tank washing machines

Portable tank washing machines and hoses

5.12 Gas Freeing Equipment 111

5.13.4 Compressed nitrogen stored on board 113

5.13.5 Liquid nitrogen stored on board 114

5.13.6 Pressure swing adsorption (PSA) nitrogen generators 114

5.13.8 Oil red inert gas generators 1 5

5.14.5 Cargo hose connections 116

5.15 Electrical Equipment and Installations in Hazardous Areas 118

6.5.2 Ship/shore communications during cargo operations 134

6.7.1 Inspection o cargo tanks prior to loading 136

6.7.2 137

CHAPTER 8 - TANK CLEANING AND GAS FREEING

Procedures and Arrangements Manual

Supervision and Preparation Responsibility

Tank cleaning plan

Pre-cleaning meeting

Preparations

Cargo Tank Washing and Cleaning General

Tank washing atmospheres

Prevention of toxic exposure during tank cleaning

Prevention of static generation during tank cleaning

Tank washing in an inert atmosphere

Tank washing in non-inert atmosphere

Precautions for sounding tanks

Transfer of wash water to slop tanks

Special Cleaning Methods Introduction

Reactive cargoes

Manual cleaning

Use of tank cleaning additives

Steaming Recirculation washing

Cleaning or gas freeing of cargo from non-cargo spaces Monitoring Tank Cleaning Operations

Precautions for sounding tanks when not using a sounding pipe

Arrangements for the Disposal of Tank Washings and Slops General

Management of slops

Mandatory prewash water

Tank Cleaning in Port Tank Cleaning Equipment Gas Freeing

Safe procedures for gas freeing after tank cleaning and cleaning by ventilation Opening up of cargo lines and handling equipment

CHAPTER 9 - ENTRY INTO ENCLOSED SPACES

Presence of inert gas including nitrogen

Oxygen enrichment Atmosphere in Enclosed Spaces Requirements for Enclosed Space Entry

9.5 Testing Before Entry 189

or Suspected to be Unsafe

1 7.4 Medical first aid after exposure to ch micals 208

10.8 First Aid and Further Care 209

13

APPENDICES 211

Appendix 4 Ship/Shore Safety Checklist Guidelines 227

DEFINITIONS

For the purpose of this Guide the following interpretations apply

Administration (flag state)

Administration (port state)

The maritim administration of the country in which the ship is registered

This is the authority that is responsible for the issuance of statutory certificates

related to the operation o a ship, and is responsible for inspections to ensure compliance with appropriate standards

The administration of the country in which a port is situated

Equipment of a design that has been tested, approved and certified by an appropriate authority, sch as a flag state administration or classification

society, as safe for use, for example, in a specified hazardous atmosphere

The condition arising when the blood is deprived of an adequate supply of oxygen so that loss of consciousness may follow

A gas or vapour, which may or may not have toxic properties, which when present in sufficie t concentrations excludes oxygen and leads to asphyxia

The lowest temperature to which a solid, liquid or gas needs to be raised to

cause self-sustaining combustion without initiation by a spark or flam or

other source of ignition

An explosion typically resulting from a catastrophic fail re of a vessel containing a liquid significantly above its boiling point at normal

atmospheric pressure

The temperature at which the vapour pressure of a liquid equals that of the

atmosphere above its surface; this temperature varies with pressure

The connecting together of electricity conducting metallic objects to ensure electrical continuity

That part of the ship which contains the whole cargo system, cargo pump rooms,

and includes the full beam deck area over the length of the ship above the cargo containmen system Where fitted, the cofferdams, ballast or void spaces at the

after end of the aftermost cargo space -or the forward end of the forward most

cargo space - are regarded as being excluded from the cargo area

Any operations involving the handling of cargo, tank cleaning, purging or venting etc

The transfer of cargo to or from the ship

Uneven flow caused by vapour pockets within a liquid

15

Certified gas free

(see also Gas free)

Certified safe electrical

equipment, fittings, arrangements and materials used in the construction

o a ch mical carrier are in compliance with the IMO IBC Code Such certification may be issued on behalf of the administration by approved classification societies

A term signifying that a tank, compartment or container has been tested by

an authorised person using an approved testing instrument, and found to be

in a suitable condition - i.e not deficient in oxygen and sufficiently free from toxic and chemical gases - for a specified activity, such as tank entry (See Approved equipment)

An instrument used for the detection of gases or vapours which works on the principle of a reaction between the gas and a chemical agent in the apparatus; the gas discolours the agent or the agent dissolves some of the gas

A system in which the contents of a tank can be measured by means of

a device which penetrates the tank, but which is part of a c.losed system preventing the release of tank contents

The isolating space between two adjacent steel bulkheads or decks; it may be

a void or ballast space

An instrument for detecting flammable gas/air mixture and usually measuring the concentration of gas in terms of its Lower Flammable Limit (LFL) No single instrument is re able for all combustible vapour

A space which has any of the following characteristics:

l mited openings for entry and exit;

Inadequate ventil tion; or

Is not designed for continuous worker occupancy, and includes, but is not limited to, cargo spaces, double bottoms, fue tanks, ballast tanks, cargo pump rooms, cargo compressor rooms, cofferdams, cha in lockers, void spaces, duct keels, inter-barrier spaces, boilers, engine crankcases, engine scavenge air receivers, sewage tanks, and adjacent connected spaces This list is not exhaustive and a list should be produced on a ship by ship basis

to identify enclosed spaces

Equipment or apparatus which will withstand, without damage and in accordance with its prescribed rating (including recognised overloads), any explosion o a prescribed flammable gas to which it may be subjected under practical operating conditions and which will prevent the transmission of flame to the surrounding atmosphere

(See Combustible gas detector)

Filling limit (or ratio) That volume of a tank, expressed as a percentage of the total volume, which

can be safely filled, having regard to the possible expansion (and change in density) of the liquid

Flame arrester A device used in gas vent lines to arrest the passage of flame into

enclosed spaces

Flame proof equipment (See Explosion proof equipment)

Flame screen (gauze screen) A portable or fitted device incorporating one or more corrosion resistant

wire woven fabrics of very small mesh used for preventing sparks from entering a t ank or vent open i ng, or for a short period of time preven ti ng t he passage of flame, yet permitting the passage of gas (not to be confused with

Flame arrester)

Flammable Capable of being ig ted and b rning in air

Flammable gas A vapour/air mixture within the flammable range

Flammable limits The minimum and maximum concentrations of vapour in air which form

explosive (flammable) mixtures are known as the Lower Explosive Limit (LEL) and Upper Explosive Limit (UEL) respectively (For the purpose of this Guide, these terms are synonymous with Lower Flammable Limit (LFL) and Upper

Flammable Limit (UFL) respectively.)

Flammable range The range of flammable vapour concentrations in air between the lower

and upper flammable limits Mixtures within this range are capable of being

ignited and burning

Flash point The lowest temperature at which a liquid gives off sufficient vapour to form

a flammable mixture with air near the surface of the liquid or within the apparatus used This temperature is determined by laboratory testng in a prescribed apparatus

Gas absorption detector (See Chemical absorption detector)

Gas dangerous space A space or zone within the cargo area which is designated as likely to contain

or zone flammable vapours and which is not equipped with approved arrangements to

ensure that its atmosphere is maintained in a safe condition at all tmes

Gas detector An instrument which alerts someone to the presence of gas, especially in

spaces where gas is not normally expected

Gas free Gas free means that a tank, compartment or container has been tested using

approved gas detection equipment and found to be sufficiently free, at the time of the test, from toxic, fammable or inrt gases for a specified activity, such as tank entry

Gas freeing Gas freeing means the process where a portable or fixed ventilaton system is

used to introduce fresh air into a tank in order to reduce the concentration ohazardous gases or vapours to a level safe for tank entry

17

lower Explosive limit

lower Flammable limit

MAK

MARPOL

(See Flame screen) Work involving fames, incendive sparks or temperatures likely to be sufficiently high to cause ignition of flammable gas The term includes any work involving the use o welding, burning or soldering equipment, blow

torc es, some power driven tools, portable electrical equipment which is not

intrinsically safe or contained in an explosion proof housing, and equipment with internal combustion engines

A document issued by a person authorised by the Master permitting specific work to be done, for a specified time in a defined area, employing tools and equipment which could cause ignition of flammable gas (see Hot work)

The International Maritime Organization is the United Nations specialised agency responsible for developing international regulations for safety at sea and pollution prevention

A spark of sufficient temperature and energy to ignite flammable gas

A gas (e.g nitrogen) or mixture of gases containing insufficient oxygen to support combustion

The introduction of inert gas into a space to reduce and maintain the oxygen content at a level at which combustion cannot be supported

(See Flammable)

A cargo which contains an inhibitor

A substance used to prevent or retard cargo deterioration or a potentially

hazardous chemical self-reaction, e.g polymerisation

An insulating device placed between metallic flanges, bolts and washers, to prevent electrical continuity between pipelines, sections o pipelines, hose strings and loading arms, or equipment/apparatus

Intrinsically safe equipment, instruments, or wiring that are incapable of

releasing sufficient electrical or thermal energy, under normal or abnormal conditions, to cause ignition of a specific hazardous atmospheric mixture in its

most easily ignited concentration

LEL (see Flammable limits) lfl (see Flammable limits)

MAK values are daily eight hour time weighted average allowable values for exposure to chemicals in the workplace applicable to healthy adults International Convention for the Prevention of Pollution from Ships

Material Safety Data

Restricted gauging system

(also known as restricted

ullage system)

Document containing information and instructions on hazardous materials

A MSDS contains details about hazards and risks relevant to the substance,

requirements for its safe handling, and actions to be taken in the event of fire

or exposure to the product MSDS is synonymous with SOS

COME is equipment required on oil tankers as part of the approved oil discharge and monitoring control system It is used to monitor the discharge into the sea of oily ballast or other oil contaminated water from the cargo

tank areas

Occupational Exposure l mits (OELs) are intended to help to control exposure

to dangerous substances in the workplace, by setting the maximum amount

of (air) concentration of a s bstance that can safely be allowed The average exposure tme in OEL lists is normally eight hours per day (often referred to as TWA-Sh or Time Weighted Average -Sh)

An instrument used to measure oxygen concentratons, expressed as a percentage by volume

Throughout this Guide the percentage of oxygen in air is referred to as 21 %, since most instrumentation in use on ships has a gauge or scale which reads to

21 % Strictly, however, the percentage of oxygen falls several hundredths of a percent below that figure, variously quoted between 20.85% and 20.95%

Filling and maintaining the cargo tank and associated p'iping system with

an inert gas - or other gas, vapour or liquid - in order to separate the cargo from air

The ph nomenon by which the molecules of a particular compound link together into a larger unit containing anything from two to thousands of

molecules, the new unit being called a polymer

Purging means the introduction of inert gas into a tank which is already in

an inert condition with the object o further reducing the oxygen content and/or reducing the conten of existing hydrocarbon or other flammable vapours to a level below which combustion cannot be supported if air is subsequently introduced into the tank

The mass of the vapour compared with the mass of an equal volume of air, both at standard conditons of temperature and pressure Th s vapour density

o 2.9 means that the vapour is 2.9 times heavier than an equal volume of air

under the same physical conditions

The Master or any officer to whom the Master may delegate responsibility for any operation or duty

The shore supervisor in charge of all operators and operatons at the terminal associated with the handling of products, or responsible delegate

A system employing a device which penetrates the tank and which, when in use, permits a small quantity of cargo vapour or liquid to be released When

not in use the device is completely closed

Upper Explosive limit

Upper Flammable limit

Vapour density

Vapour pressure

Ventilation

Venting

the effects of ship motions

International Convention for the Safety of Life at Sea

A vapour sample of known composition and concentration used to calibrate (or span) a s ip's gas detection equipment

The ratio of the weight of a volume o a substance at a given temperature

or at a different given temperature (Since temperature affects volume, the

tempera tu re a t which a spec i fic gra v i ty comparison is ma de needs to be known and is stated after the ratio.)

The electrical charge produced on dissimilar materials through physical contact and separation

The 'time weighted average' (fWA) concentration of a substance to which it is

believed workers may be repeatedly exposed, for a normal eight hour working

day and 40 hour working week, day after day, without adverse effect It may

be supplemented by a 'short-term exposure limit' (STEL)

A sort informal safety talk at the workplace prior to conducting planned

work Its objective is to raise awareness of all relevant aspects of the planned work, and particularly to discuss procedures and safety requirements

Where it is proposed to carry a liquid substance in bulk which has not been

included in the IBC Code, the appropriate authorities involved in the proposed

operation must establish and agree on a provisional assessment for the proposed operation on the basis of the guidelines referred to in MARPOL Annex IVReg .2 and must notify the IMO of the agreements When the

tripartite agreements have been notified to the IMO, the agreements of

the assessments for the products (or trade names) are issued in the form of MEPC.2/Circular

UEL (see Flammable limits)

(See Relative vapour density)

The pressure exerted by the vapour above the liquid at a given temperature

access, by natural or mechanical means using a fixed or portable system

The release of cargo vapour or inert gas from cargo tanks and associated systems

CHAPTER 1

HAZARDS AND PROPERTIES

OF CHEMICALS

1 HAZARDS AND PROPERTIES

OF CHEMICALS

that are carried as cargoes, and the precautions necessary to minimise or avoid these hazards

1.2.1 Density and specific gravity 1.5.2 Exposure to toxicity

1.2.2 Volume expansion coefficient 1.5.3 Degrees of toxicity

1.2.3 Melting point 1.5.4 Exposure limits

1.2.4 Vapour pressure 1.5.5 Precautionary principles

1.2.8 Water solubility 1.6.3 Chemicals that react with oxygen

1.3 Flammability 1.6.4 Chemicals that react with water 1.3.1 Flash point 1.6.5 Reaction of acids with water

1.3.2 Explosive/flammable limits 1.6.6 Incompatible chemicals

1.6.7 Reaction with construction materials

1.4 Static Electricity

1.7 Corrosive Substances

1.4.1 General

1.4.2 Charge accumulation and relaxation 1.7.1 General

in liquids 1.7.2 IBC Code requirements

1.4.3 Generation of static 1.8 Hazardous Cargo Information

1.4.4 Static generation during cargo operations 1.8.1 Material Safety Data Sheet

1.4.5 Static generation during tank cleaning 1.8.2 Contents of a Material Safety Data Sheet

1.4.6 Static generating portable equipment 1.8.3 Inhibited cargoes

of oil tankers in that, on a single voyage, a large number o cargoes with different properties and

inherent hazards may be carried In port, several products may be handled simultaneously a one

berth, typically involving such different operations as loading, discharging and tank cleaning

The transportation of bulk chemicals by sea not only quires purpose b ilt ships and equipment,

but also seafarers who have received specialist training, both theoretical and practical, in order

to understand the properties of the vario s chemicals and the potential hazards involved in

cargo operations

When planning the carriage of chemical cargoes it is essential that the ship's crew and the company managing the vessel are provided with a full specification of each cargo in order to ensure compliance with international stowage, handling and carriage requirements Furthermore, the cargo details

should provide the ship's crew with all of the information that they may require in order to handle the cargo safely and to minimise the impact that cargo operations may have on the environment

PHYSICAL PROPERTIES

DENSITY AND SPECIFIC GRAVITY

Density is defined as the mass of a substance per unit of volume, usually expressed in the standard (SI)

Specific gravity (SG) is the ratio of the mass of a product when measured against the mass of an

equal volume of water Because specific gravity is expressed as a ratio, it has no measurement

units However, the SG can vary according to the temperature of the product It is quite common

to see the SG quoted as 20•04 · c which refers to the density of the product at a temperature of

2o·c referenced against the den ty of water at a temperature of 4 • c This temperature reference is selected because water has its maximum density of 1,000kg/m' at 4•c

For chemical carriers, design parameters specify the maximum density of roducts that can be carried

in each cargo tank The design strength can differ between various tanks on board the same ship,

resulting in different maximum densities and maximum filling ratios

The information regarding tank strengthening can be found in the classification society's specifications for the ship, and the Master should be familiar with any restrictions that may be imposed when

loading high density cargoes Especially important is the need to be aware of and avoid the risk of

slack loading a tank This is because slack loading can lead to sloshing forces that may cause damage

to the tank structure or its internal fittings and equipment Classification societies provide information

about tank strength in various formats and the Master should ensure that the restrictions are

understood and that there is full compliance

1.2 2 VOLUME EXPANSION COEFFICIENT

Whereas the mass of a product does not vary with temperature its volume generally expands with

increasing temperature As a consequnce, the density will vary with temperature

For petroleum products, volume correction factors are calculated using American Society for Testing and Materials (ASTM) tables

23

1.2.3

temperature, using the following fonmula:

Oa = Or + ((Tr - Ta) x OCF) Where:

Oa = density at actual temperature (Ta)

Or = density at reference temperature (Tr)

OCF = density correction factorrc

Density correction factors are usually not stated in the MSDS or commodity databases, and will

typically be obtained from the loadin master or cargo surveyor

For example: Methanol

Dr at 2o·c = 0.7913 The OCF for methanol is 0.00092/'C What is the density (Oa) at 35•c?

A useful formula for calculating the maximum volume of a cargo to be loaded in a tank (Vmax) is:

Vmax = 0.98 V x (Omax/01) Where:

0.98V Omax

DI

98% volume of the tank Density of the cargo at the maximum expected temperature Density of the cargo at the loadin temperature

Cargoes with a melting point above the ambient temperature of the ship's trading area will need to

be heated in order to remain liquid The structure and equipment of a ship can impose a limitation

on the carriage of heated cargoes, which should be documented on board Exceeding this limitation could damage the cargo tank coating or coatings in adjacent spaces such as ballast tanks Excessive

heat will also create thermal stresses within the steelwork of the tank and risk structural damage Caution should be exercised when carrying high heat products Cargo in non-insulated pipes and vents may freeze Should vent lines or vents be blocked structural damage may occur due to a vacuum or overpressure developing within the tank

1.2 4 VAPOUR PRESSURE

1.2 5

The vapour pressure of a liquid is defined as the pressure exerted by its vapour when the liquid and

vapour phase are in dynamic equilibrium In a closed system at constant temperature, liquid molecules are evaporating and vapour molecules are condensing, while the pressure remains constant

Vapour pressure increases with temperature, so when stating a vapour pressure it is also important to state the temperature

Vapour pressure is expressed in kPa (100 kPa = 1 bar= 14.5 psi= 0.99 atm)

A product with a high vapour pressure at ambient temperatures is referred to as volatile

BOILING POINT

Boiling point is defined as the temperature at which the vapour pressure of a Ii quid equals the

external pressure that is surrounding the liquid The lower the external ressure the lower the

temperature at which the product will boil

In a closed cargo tank, a liquid will boil when the vapour pressure is equal to the external pressure

plus the pressure setting of the pressure/vacuum (PN) valve

The IBC Code requires that cargoes with a vapour pressure above 101.3 kPa at 37.8°( (in other words

a boiling point below 3 8°() can only be loaded in tanks that have a mechanical cooling system or that are able to withstand the vapour pressure of the cargo at 45•c

1.2.7

Vapour density is the ratio of the mass of a given volume of vapour relative to the mass of the same given volume o air Air has an arbitrary vapour density of 1, which makes it very straightfoiward to see if a particular vapour is heavier or lighter than air

At constant pressure and temperature, vapour density is proportional to the molecular mass of

the product

Most chemical cargoes have a molecular mass higher than air, which means that their vapours are

heavier than air Particular care must therefore be taken during cargo and tank cleaning operations

because vapour concentrations are likely to accumulate in semi-enclosed areas at deck level and at

the bottom of enclosed spaces

VISCOSITY

Viscosity is a measure of the resistance of a liquid to flow, or in more general terms it is the measure

of the 'thickness' of the liquid

Kinematic viscosity is a measure of the rate at which a known volume of liquid flows under the force

of gravity at a specific temperature It is measured in terms of surface area per unit of time, usually

mm2/second, whereby 1 mm2/second is more commonly known as 1 centistoke (cSt)

Dynamic viscosity measures the resistance of a liquid to flow under an applied force at a given

temperature It is equal to the kinematic viscosity multiplied by the density of the fluid and is expressed

in millipascal-seconds (mPa.s)

The viscosity of a cargo determines its pumping characteristics and the amount of residue that may be left after unloading

For most products, viscosity decreases with increasing temperature However, certain products show

increased viscosity when heated due to changes within their chemical structures

2S

1.2.8 WATER SOLUBILITY

Solubility in water can either be expressed as a percentage or graded (i.e 'nil', 'slightly' or 'complete')

Water solubility depends on the molecular polarity of the product and the number and length of carbon atoms within the molecule Hydrocarbons such as paraffins and olefins are non-polar and

insoluble in water (i.e solubility< 0.01 %)

Hydrocarbons containing oxygen, such as alcohols, ketones, acids, esters and ethers, tend to be more soluble in water as the length of the carbon chain is small (typically 3-4 maximum) As the number ocarbon atoms in the hydrocarbon chain increases water solubility rapidly decreases

Solubility is also temperature dependant For most products solubility increases at higher temperatures

A cargo with little or no solubility in water will form a separate layer above or below the water layer, depending on the density of the product relative to fresh water, which has a density o 1.00 tonnes/m' Many water insoluble products have a relative density less than 1.00 and will float on top of water The

most common group of hydrocarbon cargoes that are heavier than water are chlorinated solvents which

rises and, as a result, the concentration of flammable vapour in the air also increases Should the

temperature of the liquid exceed the flash point, the threat of an explosion from an ignition source becomes real

The explosive/flammable limits of any flammable liquid are defined as the range of concentration of flammable vapour (expressed as % by volume in air) in which an explosion can occur upon ignition It

is the oxygen in air which mixes with the flammable vapour to create an explosive mixture

At the bottom of the range is the lower explosive/flammable limit (U:ULFL), below which there is

insufficient flammable vapour in the air to support combustion At the top of the range is the upper explosive/flammable limit (UEUUFL), above which there is insufficient air within the flammable vapour

to support combustion

Mixtures of flammable vapours and air which fall between the LEL and the UEL are explosive and are easily ignited by an ignition source

The flammable range of certain c emicals is greater than for oil cargoes For example, methanol has

a flammable range of 30% (LFL 6% to 36% UFL) This, together with other characteristics (low flash point, low boiling point and high vapour density) dictates that special precautions are taken in the

handling of such cargoes

It should be noted that the terms 'explosive limit' and 'flammable limit' are for practical

shipboard purposes synonymous

Figure 1.1 - Flammability Composition Diagram - Hydrocarbon Gas/Air/Inert Gas Mixture

This diagram is illustrative only and should not be used for deciding upon

acceptable gas compositions in practical cases

The effect of inert gas on flammability

When an inert gas is added to a hydrocarbon gas/air mixture, the result is to increase the

Lower Flammable Limit hydrocarbon concentration and to decrease the Upper Flammable

Limit concentration

These effects are illustrated in Figure 1.1, which should be regarded only as a guide to the

principles involved

Every point on the diagram represents a hydrocarbon gas/air/inert gas mixture, specified in terms of its hydrocarbon and oxygen content Hydrocarbon gas/air mixtures without inert gas lie on the line

AB, the slope of which reflects the reduction in oxygen content as the hydrocarbon content increases Points to the left of the line AB represent mixtures with their oxygen content further reduced by the addition of inert gas

The lower and upper flammability limit mixtures for hydrocarbon gas in air are represented by the

points C and D As the inert gas content increases, the flammable limit mixtures change as indicated

by the lines CE and DE, which finally converge at the point E Only those mixtures represented by

points in the shaded area within the loop CEO are capable of burning

On this diagram, changes of composition due to the addition of either air or inert gas are represented

by movements along straight lines directed either towards the point A (pure air), or towards a point

on the oxygen content axis corresponding to the composition of the added inert gas Such lines are shown for the gas mixture represented by the point F

It is evident from Figure 1.1 that, as inert gas is added to hydrocarbon gas/air mixtures, the flammable range progressively decreases until the oxygen content reaches a level, generally taken to be about

11 % by volume, when no mixture can burn The figure of 8% by volume of oxygen, specified by

SOLAS for a safely inerted gas mixture, allows a margin beyond this value

27

1.4

1.4 1

moves along the line FA and therefore enters the shaded area of flammable mixtures This means that all inerted mixtures in the region above the line GA go through a flammable condition as they are

mixed with air, for example, during a gas freeing operation Those mixtures below the line GA, such

as that represented by point H, do not become flammable on dilution It should be noted that it is possible to move from a mixture such as F to one such as H by dilution with additional inert gas (i.e

purging to remove hydrocarbon gas)

STATIC ELECTRICITY

GENERAL

Static electricity is the build up of an electrical charge on the surface of objects Materials are usually

electrically balanced with an equal number of positive and negative charges When two unlike

materials are in contact with each other these charges can flow from one to the other creating

an imbalance in the number of positive and negative charges This process is amplified by friction, for example when a cargo moves through a pipeline Static charges build up on poor electrical conducting materials (insulators) where the charge cannot come into balance with its surroundings

When two materials with an accumulated static electrical charge are brought close together, the two charged surfaces will seek to equalise their potential If the difference in potential is large enough there will be sufficient energy for the charge to jump the gap between the two materials and a spark

will be generated

1.4 2 CHARGE ACCUMULATION AND RELAXATION IN LIQUIDS

The ability of different liquids to conduct electricity varies The electrical conductivity of a liquid is

measured in pico siemens (pS) per metre Charge accumulation does not occur in liquids having conductivity well above 10 pS per metre Such liquids are called non-accumulators or conductive

materials, the most common being salt water which is a good conductor of electricity

However, at a conductivity of below 10 pS per metre, the accumulation of an electrical charge may be

significant l quids of low conductivity are called static accumulators or non-conductive

For safety reasons, all liquids with a conductivity reading of less than SO pS per metre are considered

to be non-conductive

1.4 3 GENERATION OF STATIC

The risk of gen rating static sparking can occur during the following operations on board a

chemical carrier:

1 loading and unloading

An electrostatic charge is generated within the liqui as it flows through pipelies The amount of charge generated will depend on the ability of the liquid to conduct electricity, a property known as

A static charge will be produced when water is forced, under high pressure, through the nozzle

of a tank cleaning machine As a result, the water mist inside the cargo tanks may become

charged A charge can also build on the nozzle of the tank cleaning machine unless the machine is

electrically grounded

5 Sampling/gauging

Objects such as ullage probes or sampling equipment may already contain an electrostatic charge

prior to being lowered into a tan Lowering and raising such equipment in and out of a cargo tank may also generate a static charge on the line

6 cargo inhibitors

Adding o substances sch as powdered inhibitors and other similar material may gen rate a static

charge especially if added by free falling the s bstance into the tank

1.4 4 STATIC GENERATION DURING CARGO OPERATIONS

A liquid flowing into a cargo tank can be charged by friction within the loading pipeline and remain charged within the cargo tank The static charge within the cargo will slowly dissipate as the

difference in potential between the cargo and the tank structure equalises This process is called

charge relaxation and its speed depends upon the conductivity of the liquid

Should the cargo contain water droplets, friction occurs when these droplets settle by gravity through the liquid in the tank (assuming that the liquid has a density less than that of water) Similarly, if

the liquid contains a non-dissolved gas, the liquid could become charged when the gas bubbles

rise to the surface of the liquid in the tank I both of the above cases a vertical electrical current is

established and a high voltage may result at the surface of the liquid, which is known as a surface

voltage Over time, depending on the conductivity of the liquid, the charge will equalise with the tank structure as described above

A static charge can also be generated if the liquid is allowed to fall freely into a cargo tank (splash

filling), where friction with the air through which the li uid falls adds a further charge to the liquid

Charged foam, generated when splash filling some liquids, will tain a charge for a much longer

time than the bulk of the liquid, as the thin film of foam bubbles at the liquid interface o ly pro ides

a very narrow path for charge relaxation to the tank structure

1.4 S STATIC GENERATION DURING TANK CLEANING

A statically charged mist is formed inside the cargo tank when washing, particularly with hot water or

a cleaning medium or when injecting steam into the tank

Friction is also generated within the tank cleaning machines at the nozzle, along the water jet and on impact against the tank surfaces

Statically charged mists can remain inside empty cargo tanks for a far longer tim than the static

charges generated within a liquid product during the loading and discharging process Relaxation of

a static charge within the mist can only happen as fast as the time it takes for the mist to conde se

on to the tank surface Such high voltages can be generated within these mists that sparks can occur

e ven in a i r

1.4 6 STATIC GENERATING PORTABLE EQUIPMENT

When an insulated or unearthed electrode is immersed in an electrostatic field it becomes charged,

but the charge has no path to earth If the difference in electrical potential is large enough a spark

can then jump from the electrode to the tank wall or to the surface of the liquid If the atmosph re is

flammable, ignition will occur

29

1.5

1.5 1

1.5 2

1.5 3

cans and portable pumps as well as ullaging and sounding equipment The lines used to lower such

equipment are also potential generators of static electricity, particularly ropes made o synthetic fibres Ropes made of synthetic fibres should never be used to lower equipment into tanks

1 C hemical

This relates to specific ch mical compoundsThe toxicity of such compounds or mixture o

compounds is measured in terms of the exposure time needed to cause an effect

There are three ways where toxic poisons can enter the body:

1 By being swallowed (oral toxicity);

2 By absorption through the skin, eyes and mucous membranes (dermal toxicity); or

3 By inhalation as a vapour or mist (inhalation toxicity)

A chemical may be toxic by more than one of these ro tes For example, toxic vapours and mists

affect people mostly via the respiratory system, but they can also be absorbed through the skin

A highly toxic substance is one where only a small quantity of the substance is needed before harm

is caused

During ch mical carrier operations, contact with a liquid or inhalation of its vapour are the most likely

forms of exposure Safe operating procedures, a full understanding of the dangers involved and the

use of the correct Personal Protective Equipment (PPE) will all h lp to protect the crew from exposure

to toxic products

DEGREES OF TOXICITY

Toxicity can be defined as acute, sub-acute or chronic:

A substance with acute toxicity is sufficient to cause harm almost immediately after exposure

Substances commonly called poisons have extreme acute toxicity;

A substance with sub-acute toxicity will only start to show symptoms after repeated exposure in doses too small to cause an immediate acute effect; or

A substance has chronic toxicity if its effects only appear after repeated exposure over a period of

time Examples are substances which are carcinogenic (cancer inducing) such as benzene

An exposure limit is the maximum concentration of a chemical substance or vapour in air that a

person can safely be exposed to, day after day, without suffering any adverse health effects Exposure limits are generally expressed as a Threshold Limit Value (TLV)

regular working dose of a hazardous or toxic substance These exposure limit definitions should not

be regarded as the absolute dividing line between what is safe and what is a hazardous working

environment It is always good operating practice to keep vapour concentrations to an absolute

The most widely used TLVs are those issued by the American Council o Governmental and Industrial Hygienists (ACGIH) The values are updated annually in the light of new knowledge, so it is always

TLV - TWA (Time Weighted Average)

The concentration of vapour in air which may be experienced for an eight hour day or 40 hour week throughout a person's working life This is the most commonly quoted TLV

TLV - STEL (Short Term Exposure Limit)

The maximum concentration of vapour in air allowable for a period of up to 15 minutes, provided

that there are not more than four exposures per day and a least one hour between each The STEL is always greater than the TWA However, this figure is not always provided for all substances

TLV - C (Ceiling)

for a given substance

chemical and its vapour are safely contained within the boundaries of the approved cargo system, and

by the use of closed monitoring and control systems, the crew will be protected effectively

cargoes However, accidents and fail re of equipment can occur and therefore it is essential that the

sip's containment systems are well maintained and tested on a regular basis in order to ensure that they work as designed

sbstances Disconnecting cargo hoses at the manifold or while taking cargo samples are typical

examples of where exposure can occur During such operations, it is essential that crew members are properly protected by appropriate PPE

REACTIVITY

GENERAL

Most chemicals carried by sea are chemically stable and, provided that they are appropriately handled, can be loaded, stowed and discharged safely Some chemicals, however, require special care to ensure that they remain in a stable condition Reactive chemicals may be inh re tly unstable or, when in

1.6.2

A reaction which produces heat is called an exothermic reaction The speed of a reaction varies widely depending on the ch micals involved but generally the reaction rate accelerates as heat is generated

A very fast reaction may cause an explosion

A chemical that must absorb heat to trigger a chemical reaction is known as endothermic This does not usually present a hazard on board so long as the chemical is kept separated from a heat source

For the sake of clarity reactive c emicals are categorised as follows:

Unstable or self-reacting chemicals, either decomposing or polymerising;

Chemicals capable of reacting with oxygen in the air, either forming peroxides or liable to decomposition;

Chemicals which react with water to emit dangerous gases; and

Incompatible chemicals which react dangerously if mixed together

UNSTABLE CHEMICALS

Reaction characteristics

Unstable chemicals can self-react within their own mass and do not need another substance to trigger a reaction Decomposition or polymerisation is the most typical reaction that can occur within unstable chemicals carried on board chemical tankers A compound may change from a free flowing

liquid into a viscous one or even a solid

Polymerisation may occur spontaneously with no outside influence, or it may occur if the compound

is heated, or if a catalyst or impurity is added Polymerisation may, under some circumstances, be dangerous, but may be delayed or controlled by the addition of inhibitors

Substances that polymerise may generate heat and/or toxic and flammable gases Polymerisation is often initiated by high temperatures, or by a reaction with small amounts of other c emical impurities that act as a catalyst which further accelerates the rate of reaction

The most common catalysts that accelerate polymerisation are acids, alkalis and metals

The main danger of exothermic polymerisation in a confined space is an increase in pressure, in addition to the emission of potentially toxic and flammable vapours Polymerisation may be prevented

by controlling the transport temperature and by adding a chemical stabiliser or inhibitor, which neutralises the impact of the catalyst

Substances which polymerise, such as styrene monomer and vinyl acetate monomer, exhibit a unique property which allows individual molecules of a particular substance (monomer) to combine with each other to form long chain polymers Most polymerisation reactions are exothermic, and are characterised by an accelerating reaction rate until all of the monomer molecules are consumed The speed of a polymerisation reaction can be extremely dangerous

If the polymerisation process starts spontaneously, the product is considered to be self-polymerising Although spontaneous polymerisation can occur at ambient temperatures, it is very often initiated by elevated temperatures, either due to environmental conditions or adjacent heat sources

Spontaneous polymerisation of a monomer cargo presents the following dangers:

The generation of heat which accelerates the speed of the chemical reaction;

The rapid volumetric expansion of the product causes ov r pressurisation of the cargo tank with a consequent danger of rupture of the containment system;

The rupture of the tank may lead to ch mical reactions with other cargoes in adjacent cargo tanks;

polymerisation process produces heavier and more viscous liquids, or even solids, which may

block the tank vents so that the pressure inside the tank increases even further; and

Once solidified the polymer occupies a greater volum than the corresponding volume of

liquid monomer

Cargoes that polymerise will usually contain an inhibitor that stops the initiation of the polymerisation reaction These inhibitors are designed to be effective for a set period of time at a specified

temperature It is therefore essential that the timed effectiveness of the inhibitor is sufficient for the

voyage and includes a good safety margin

Since elevated temperature can reduce the effectiveness of the inhibitor or reduce its effective ltte, it is

essential that heat sources are kept away from these cargoes and that the temperature is closely monitored

on at least a daily basis, or more frequently if recommended by the cargo manufacturer or shipper

An increase in cargo temperature that is not related to ambient weather conditions or adjacent cargo

temperatures may be an early indication that a polymerisation process has started In such instances,

the cargo manufacturers should be contacted immediately to advise appropriate counter measures

which may include the addition of more inhibitor or the cooling of adjacent structures Should the

increase in temperature be rapid then the decision to jettison cargo may be the only option in order

to avoid serious structural damage to the cargo tank and the ship

Effect of inert gas on inhibited chemicals

Inhibitors usually require oxygen to be effective and this is mainly obtained from oxygen dissolved

within the product itself Inhibitors may also require the presence of a certain percentage of oxygen

in the tank atmosphere in order to be effective It is good practice for this minimum level of oxygen

to be stated on the inhibitor certificate As a general rule, a cargo that contains an oxygen dependent inhibitor should not be inerted before loading or during carriage If it is required to inert the cargo this

should be carried out before unloading

Where products are carried without inerting (tank size not greater than 3,000m3) such cargo must not

be carried in a tank requiring inerting under the requirements of SOLAS Chapter 11-2

If nitrogen is bubbled through an inhibited cargo (such as when compressed nitrogen is used to clear the cargo hose after loading) the nitrogen will deplete the oxygen dissolved in the liquid, thereby

requiring the inhibitor to take oxygen from the atmosphere, see also Section 6 7 8

Should there be any doubt, additional advice should be sought from the shipper

IBC Code requirements

The IBC Code specifies the precautions to be taken against spontaneous decomposition and

polymerisation, by the use of additives (stabilisers and inhibitors) uniformly distributed within the mass

of the product, and by control of the carriage temperature

The IBC Code requires the anufacturer of the unstable chemical being carried, who may not necessarily

be the shipper, to be responsible for providing the ship with a number of critical safety instructions

concerning the additive

These instructions must be provided in the form of an inhibitor certificate showing:

Which additive has been or should be introduced into the product, and in what quantities;

When the additive was or should be introduced, and for how long it is expected to be effective;

The temperature conditions to be met in order to preseive the effectiveness and lifetime of

the additive;

Whether dissolved oxygen must be present in the liquid for the inhibitor to be effective;

The oxygen concentration that is required within the uage space in order for the inhibitor to

remain effective; and

What action should be taken should the length of the voyage last longer than the effective

lifetime of the additive

33

1.6 3

to be present in cargo vapours Therefore, wherever cargo vapours may condense, for instance inside

vent valves and flame arresters, there is a risk that polymerisation may occur

The IBC Code also contains provisions against the exposure of cargoes to excessive heat The

preventive measures include prohibition of carriage in tanks or pipelines close to those used for

products whose temperature is high enough to initiate a reaction in the unstable chemical, and a

requirement to blank the tank's heating systems

CHEMICALS THAT REACT WITH OXYGEN

Reaction characteristics

Some chemicals react with oxygen These include ethers which react slowly with oxygen in the air,

or with oxygen dissolved within the mass of the liquid to form peroxides Once formed, organic

peroxides can act as reaction catalysts, initiating a polymerising reaction The main danger is that

a normal or elevated temperatures they are liable to trigger exothermic and self-accelerating decomposition The decomposition can be initiated by heat, contact with impurities (e.g acids,

heavy metal compounds and amines), friction or impact Some organic peroxides may decompose explosively, particularly in confined spaces such as a cargo tank

In order to prevent the formation of organic peroxides when carrying such cargoes, the tank should

be fully inerted for the duration of the voyage A further precaution is ensuring that the carriage

temperature is as close to ambient as possible

Natural products such as animal and vegetable oils react slowly with oxygen as a part of the

decomposition process (also known as putrefaction) These oils slowly oxidise in the presence of air by the action of bacteria present within the oils

There are two dangers associated with this decomposition process:

The process consumes oxygen and produces carbon dioxide (CO,) creating an asphyxiating atmosphere;

Hydrogen sulphide (H

2S), a hazardous gas, can be produced as part of the decomposition

process if il in contact with water Tanks containing bunkers or slop tanks containing

vegetable oil washings are a particular risk, especially after prolonged storage over several days at elevated temperatures

The process of decomposition is accelerated by heat and the presence of water

IBC Code requirements

For cargoes susceptible to the formation of peroxides, the IBC Code specifies measures to control the environment or atmosph re inside cargo tanks, including the use o an inert gas

Inert gas with a very low level of oxygen is required and for this reason nitrogen is the preferred

medium The IBC Code requires sufficient inert gas to be available to purge air o t of the cargo system before loading To compensate for losses during transport, in order to ensure that a positive over pressure is maintained in the loaded tank, sufficient inert gas needs to be available so that the tanks can be topped up throughout the voyage

The cargo handling system for cargoes susceptible to the formation of peroxides should be

independent of all others

1.6 4 CHEMICALS THAT REACT WITH WATER

Reaction characteristics

The reaction of some chemicals with water, including humidity in the air, can generate gases that are

flammable or toxic or both lsocyanates, such as Toluene diisocyanate (TOI), react violently with water to form carbon dioxide, an asphyxiate gas The reaction can also lead to over pressurisation of the tank

1.6 S

1.6 6

of heating coils/lines and purging lines should also be addressed

JBC Code requirements

from water, and be carried under a dry atmosphere

such as water tanks, ballast tanks (unless those tanks are empty and dry) or cargo tanks containing

lines) should not pass through the tank, unless encased in a tunnel If temperature control is required,

The entire cargo system (tank, pump, lines and vents) should be completely segregated from other

cargo and ballast systems

The tank should not be cleaned with water unless the shipper of the product or the shipowner has

specified a safe procedure for doing so

REACTION OF ACIDS WITH WATER

Reaction characteristics

The mixing of some acids with water greatly increases their corrosive effect and a violent reaction can occur Company procedures should be followed when the passivation or pickling of stainless steel

tanks takes place

cleaning, and in order to prevent a violent reaction, acids or alkalis should always be slowly added to

alkalis, the temperature may rapidly rise to above 1 oo ·c and cause splashing

20-80% Corrosiveness is further enhanced when acid is diluted with sea water because of the

amount of water needs to be introduced in the initial phase in order to dilute the acid residues quickly

INCOMPATIBLE CHEMICALS

Reaction characteristics

JBC Code requirements

in a hazardous manner with other cargoes, residues or mixtures, must:

1 Be segregated from such other cargoes by means of a cofferdam, void space, cargo pumproom,

other pumproom, empty tank, or tank containing a mutually compatible ea rgo;

containing such cargoes, unless encased in tunnel; and

35

Several authoritative bodies have divided chemical cargoes into groups, defining c1te a for

incompatibility between them, and have published lists of incompatible cargoes The most familiar is published by the United States Coast Guard (USCG) (CFR 46 part 150) According to USCG, a mixture

of two chemicals is considered hazardous (and the chemicals in question declared incompatible) when, u der specified t est conditions, the temperature rise of the mixture exceeds 2s•c or a gas is produced as a result of the reaction

Whether cargoes within a pair of groups are incompatible is indicated in a table k own as the USCG Compatibility Chart

The USCG Compatibility Chart assigns each bulk chemical cargo to one of 22 Reactive Groups and

14 Cargo Groups Reactive Groups contain those chemicals which are the most reactive, so that

dangerous reactions can be id ntified between members of different Reactive Groups and between

members of Reactive Groups and Cargo Groups Chemicals assigned to Cargo Groups are much less

reactive and do not react dangerouly together

Two incompatible cargoes are not aowed to be stowed adjacent to each other Caution must be exercised regarding overlapping tanks

While the USCG table gives general indications, the footnotes and data sheets for any two particular cargoes should always be consulted because there are

exceptions to the Compatibility Chart

Tank 2 Starboard and Tank 3 Port are not shared*

Stowage NOT acceptable for

non-compatible cargoes, because bulkheads are shared

•stowage of non-compatible cargo is acceptable when tank comers are fonmed of a 'cructfonm Joint' acceptable to the nag administration as providing dou le barl!'ler separation

Figure 1.2 -Cargo Compatibility

1.6.7 REACTION WITH CONSTRUCTION MATERIALS

The materials used in construction of the cargo systems must be compatible with the cargo to be

carried In addition, care must be taken to ensure that no incompatible materials are used during

maintenance Incompatible materials may trigger a self-reaction within the cargo that can be

dangerous to ship and crew, or may cause cargo contamination

Although chemical tankers are designed to contain cargoes safely within the cargo system there are occasions when small amounts of a product, such as cargo samples, are required to be stored outside the containment system, within the cargo area The IBC Code specifies requirements for the safe

storage of cargo samples

Corrosive substances

Corrosive substances destroy human tissue on contact (e.g skin, eyes and mucous membranes in

the mouth and the respiratory tract) They can also corrode metal or other materials used in ship

construction at a very high rate Some corrosive substances have an anaesthetic effect on the skin so that the harmful effects of exposure are only felt at a later stage

The most common corrosive liquids are acids and alkalis, which can be organic or inorganic in origin The most dangerous corrosive products can cause severe burns after only a very short exposure time Some substances become more corrosive in the presence of water, or produce corrosive vapour when

in contact with moist air

Alkalis and acids if mixed can form a violent reaction These two cargo types should be kept totally

separated from each other and not be stowed in adjacent tanks

Acids

The most corrosive acids are nitric acid, sulphuric acid, chlorosulphonic acid and chloropropionic acid Formic acid and acetic acid are also highly corrosive in concentrations above 90% Some acids are

known as fuming acids as they produce corrosive acidic vapours

A few acid cargoes are flammable but the non-flammable acids can react with metals to produce

hydrogen and can also create a flammable atmosphere

Specific acid ch racteristics:

Nitric acid is a powerful oxidising agent and can cause fire when in contact with combustible

materials such as wood and cotton Fabric materials should therefore never be used on spilled

nitric acid or any other oxidising agent;

Sulphuric acid and chlorosulphonic acid react violently with water, the resulting reaction

producing large amounts of heat which can cause the water to boil;

Chlorosulphonic acid, dichloropropionic acid, hydrochloric acid and oleum are toxic by inhalation;

Chloroacetic acid is toxic by ingestion; and

Acetic acid and acetic anhydride are flammable Most other acids are themselves non-flammable

but, in general, acids react with metals to evolve hydrogen which is highly flammable

Some acids have a relatively high freezing point and need to be heated for sea transport to prevent solidification Examples are acetic acid, oleum (whose freezing point varies with its concentration) and super-phosphoric acid

37

1.Z2

Common inorganic alkalis such as potassium hydroxide and sodium hydroxide (caustic) are corrosive

to aluminium, zinc and galvanised steel, so these materials should not be used within the cargo containme t system Other corrosive alkalis include aliphatic and alicyclic amines, pyridines, sodium

slphide solutions and ammo ium sulphide solution

IBC CODE REQUIREMENTS

The IBC Co e requires secure containme t of corrosive cargoes within a cargo system constructed of

sitable corrosion resistant material

Acids must not be carried in tanks where any boundary is formed by the ship's sh ll plating Because other parts of the ship's structure may come into contact with a corrosive cargo as a result of a leak,

arra gements must exist to d tect a leak into spaces adjacent to the cargo system

1.8 1 MATERIAL SAFET Y DATA SHEET

SOLAS requires that a Material Safety Data Sheet• (MSOS) must be provided to the vessel for each

MARPOL Annex I cargo to be loaded There is not a corresponding SOLAS requirement for MARPOL

Annex II cargoes Nevertheless, the IBC Code requires that: 'I nformat i on shall be on board, and ava il able to a ll concerned, g i v i ng the necessary data for the safe carr i age of the cargo in bulk '

In effect therefore the !BC Code requires that an MSDS is pro ided by the shipper to the ship before loading for each MARPOL Annex II cargo

The Master should enure that, as far as practical and as part of the ship/shore exch nge, a copy

of the ' data for the safe carr i age of the cargo i n bu l k ' provided to the ship is provided to the cargo

receiver (terminal or transhipment ship/barge) so that risk c ntrol measures taken during loadin , carriage and unloading are based on accurate information

It is important that:

An MSDS is pro id d for each cargo;

The IBC Co e product name, ship type and pollution category are pro idd; and

Other required information on properties and emergency measures is provided in specific sections

of the MSDS

An example of a suitable MSDS template is included in Appen ix 5

It is recommended that the information in an MSDS should be presented in 16 sections and in the order

sown below:

Section 1: Identification - Includes the product or the ixture name or identity (GHS identifier)

To include the manufacturer or distributor's trade name, ddress, phone n mber; emergency phone number; recommended use and restrictions on use as it ppears in

the IBC Code or most recent edition o MEPC.2/Circular If the GHS id ntifier is different from the IBC Code product name or from the latest edition of MEPC.2/Circular, then this

product name should be stated in Section 14 of the MSDS Section 2: Hazard(s) identification - Includes all hazards associated with the product

Section 3: Composition/information on ingredients - Includes information on chemical

ingredientswater content, any inhibitors and denaturing agents which may be present

The ter m Ma t erial Safety Data Sheet ( MSOS ) is syncnymous wrth Safety Oa t.a Shee l (S O

1.8 3

Section 4: First aid measures - Includes important symptoms and effects, acute or delayed

symptoms with recommended or required treatment

Section 5: Fire-fighting measures - Lists suitable extinguishing media and techniques,

equipment, and specific chemical hazards arising from fire Section 6: Accidental release measures - Lists emergency procedures, protective equipment, and

proper methods of containment and clean up

Section 7: Handling and storage -lsts precautions for safe handling and storage of cargoes,

including incompatibilities with other cargoes/products (e.g by reference to the use of the USCG Compatibility Chart)

Section 8: Exposure controls/personal protection - Lists Threshold Limit Values (TlVs), means of

vapour detection, appropriate controls, and Personal Protective Equipment (PPE)

Section 9: Physical and chemical properties - Lists the physical and chemical characteristics of

the substance including viscosity and boiling point where appropriate Section 10: Stability and reactivity - Lists chemical stability and possibility of hazardous reactions Section 11: Toxicological information -Includes routes of exposure, related symptoms, acute and

chronic effects, and numerical measures of toxicity

Section 12: Ecological information - Includes ecotoxicity, persistence and degradability,

bioaccumulation potential, and mobility in soil

Section 13: Dispos l considerations - Description of wastes and information on their safe

handling and methods of disposal

It should be noted that Annex II o MARPOL 73/78 regulates discharge of residues of chemical liquids transported in bulk

Section 14: Transport information -Hazardous Materials or Dangerous Goods shipping information:

• MARPOL Annex I or Annex II carriage requirements with reference to IBC Code and

Tripartite agreement as appropriate;

• Ship type carriage requirement - 1, 2 or 3; and

• Cargo type -X, Y or Z Cleaning products that are carried on board the ship that are not carried as cargo may

be referenced under:

• MEPC.2/C ire - Provisional Categorisation of liquid Substances; and

• The IMDG Code -Transport information includes: UN Number; Proper Shipping

Name; Transport Hazard Class; Packing Group; Environmental Hazards This infonmation covers transport of packaged goods (e.g drums, boxes, containers and portable tanks)

Section 15: Regulatory information - Safety, health and environmental regula ons specific to

the product

Section 16: Other information - Includes the date of reparation or last revision

If sufficient information necessary for the safe transportation of the

cargo is not available, the cargo must be refused