sea transport of liquid chemicals in bulk

8/13/2019 Sea Transport of Liquid Chemicals in Bulk

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4 MATERIALS

4. 01 Iron, steel

Mild steel and high tensile steel is, and will continue to be the most important material in the building of

chemical tankers and their cargo tanks.

Steel is attacked by only a few products, mainly acids and, of course ballast and washing water. Steel

itself contaminates very few products, one of them being high purity caustic soda. Rust, however,

creates many problems with cargo contamination. Rust may contaminate a product in the form of minute

particles staying suspended in viscous heavy liquids such as glycols and caustic soda. Rust may

accelerate polymerization in polymerizable products. Rust will be soaked in with remains of previouscargoes, mainly from heavy oils, which will contaminate the next cargo. Rust will, above all, render tank

cleaning much more difficult, cause delays and perhaps cargo claims.

ue to the above reasons steel is practically never used in chemical tankers without a protective coating,

see !. "#. $oating techniques have advanced greatly in latter years. Still, however, one does not dare to

use coatings for products, which are really aggressive to steel, e g acids %such as phosphoric acid&. 'ne

has to reckon with coating defects where corrosion will start. 'ne exception to this is rubber linings,

which have been in use a long time with corrosive cargoes.

(or information on a particular product)s sensitivity to steel steel and rust see ref %*&, +ppendix and #.

-enerally speaking, steel is resistant to alkalies, even in high concentrations %caustic soda, ammonia&.

4.02 Stainless steel

Stainless steel has increased greatly in use as tank material in later years. he motif is not only a better

chemical resistance but primarily it provides for a greater ease in tank cleaning and inspection. hus

cargo contamination hazards can be reduced.

he stainless properties are due to the formation of a very thin, passive layer of chromium oxide on the

surface. he care of stainless steel tanks aims at maintaining this protective film intact.

Stainless steels possess a number of advantageous proper ties, rustproofness, however, is not

guaranteed. t depends on the correct treatment of the tanks and on what products carried. + shortreview may be of interest.

he commonly used stainless steels have the following typical compositions/


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0ow carbon contents are required to make the steel corrosion resistant near the welds. $arbon tends to

bind chromium to form chromium carbide in the heat affected zone near the welds, thus reducing the

corrosion resistance locally. he addition of titanium has a neutralizing effect on this process and

therefore slightly higher carbon contents can be tolerated. he addition of small amounts of nitrogen

increases the tensile strength of the steel considerably. Such steels are often used in more highly

stressed parts such as corrugated bulkheads sub1ected to corrosion from both sides, where weight

reduction is at a premium.

-eneral corrosion of stainless steels from corrosive cargoes such as phosphoric acid is of a low intensity

and can therefore be disregarded.

2itting corrosion might cause severe damage. o avoid this happening it is important to choose thecorrect type of stainless steel. -enerally speaking high molybdenium contents is beneficial in this

respect. 2ittings may take the shape of small holes, *34 mm in depth and diameter to begin with. +t

times they are almost hidden below the surface of the steel with an 5entrance hole5 of only a few tenths

of a mm. with a cavity of *34 mm below. hey are therefore sometimes very difficult to detect. So called

dye3penetrant tests are useful for detection when one knows approximately where to look for defects.

2itting may develop in a generally corrosive surrounding, especially when the surface is disturbed or

when some extra chemical aggressive age.nt is present such as/

3 chlorides %seawater, 5salt5&. $ontents above some *""34"" ppm are generally dangerous whentogether with some other corrosive agent such as phosphoric acid. (luorides have a similar effect.

3 particles of iron3or other materials on the surface

3 craters or pores in weld deposits

3 weld slag or slag from rolling mill

3 surface defects, micro cracks, rough surfaces

3 lack of oxygen renders formation of chromium oxide difficult

3 high temperatures %above ca !""$ corrosion rates in crease rapidly&

$revice corrosion may occur in narrow spaces where the corrosive agent can enter but without

circulation, with a lack of oxygen as consequence.

ypical locations/

- under bolted connections- under cargo sediments

- under paint on a stainless steel surface.

he following rules for maintenance of stainless steel apply/

*. 6eep chlorides away. +void seawater in the tanks and rinse with freshwater carefully after seawater

washing. Seawater must never be permitted to dry up and leave salt crusts on the surface. 6eep the

hatch covers closed and the airpipes protected to prevent seawater or a saline atmosphere entering the

tanks. 2referably change footwear before entering a tank when at sea.

4. Remove any particles or sediments such as rust, particles from grinding operations, cargo sediments

%phosphoric acid&, 5scale5. $argo remains to be removed as soon as possible after discharge.

7. Surface finish. ank surfaces to be kept bright and free from scratches. his means3that possible

corrosion or other mechanical defects should be ground and polished to the original finish. 8ormally

grinding disc 5grain 9"5 can be used, followed by a final operation with 5grain *4"5. 0ocal pittings of

substantial depth can be welded, minor pittings ground away.

!. nspect for corrosion after each cargo, especially tank bottoms and under deck. n order to avoid salt

crystals forming on the tank bottom *"34" cm fresh water is sometimes kept in the tanks on the ballast

voyage.


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#. $leaning can normally be carried out with all common cleaning agent:s such as 5emulsifiers5, 5solvent

cleaners5 and alkaline cleaners as well as caustic soda.

;. Stainless steel tanks are sometimes passivated by application of *43 *# < nitric acid %=8' 7& . his

acid is strongly oxidizing. he procedure assists in building up the passive chromium layer on the steel,

thus increasing its chemical resistance. 2assivation is normally carried out after tank surface repairs in

order to assist the normal passivation in air. f aggressive cargoes are to be loaded within 4! hours all

repairs must be passivated. n practice 5passivation5 with nitric acid is often used for the removal of dis3

colorations and particle contaminations on the surface. n factlit is being more used as a thorough

cleaning agent than a passivating chemical. 2assivation is normally carried out with a brush or, for a

whole tank, by spraying, +fter *"34" min the acid should be washed off with large amounts of fresh

water. M2'R+8/ 8itric acid gives off nitrous gases which are very toxic %with delayed effects&.>entilate completely and use breathing masks for larger areas in confined spaces? he atmosphere can

be tested for nitrous gases by means of test tubes, see 7. *". @se protective clothing and goggles. 8itric

acid is usually available in ;" *Ao concentration. Be careful/ spills may cause self3ignition of organic

matter. See also ref Ci& for safety precautions with nitric acid.

D. 2ickling is the toughest way of cleaning stainless steel. his method is used for the removal of welding

slag, oxides and discolorations from welding or discoloration from cargoes. 2ickling paste, consisting of,

among other components, nitric acid and hydrofluoric acid shall be applied with the same precautions as

nitric acid above. 2ickling should be followed by passivation with nitric acid. 2ickling involves a lot ofwork and can only be used on relatively small areas, unless carried out by specialists.

4.03 Cuprous alloys

$opper and its alloys corrode in many cargoes and may contaminate them, e g styrene, phenol, vinyl

chloride, aniline, ammonia solutions etc. $heck your cargo against information given in e g the

$S3-uide ref %*&, %!& and %#& or +ppendix * and #. 2articularly aggressive are the ammonia compoundsE

they cause inter 3crystalline corrosion of cuprous alloys very rapidly. he ob1ect in question

disintergrates very soon.

=eating coils of cuprous alloys are attacked by caustic soda %8a'=& after being used a long time. But for

a limited number of voyages no serious problems seem to arise. +s a general rule in chemical tankers

one tries to replace cuprous alloys with stainless steel %+S 7*; or 7*D&. 'ne must remember, however,that stainless steel easily scores against stainless steel in sliding contact %in valves etc& and design

accordingly, using also other materials.

4.04 Magnesium an aluminium, alloys

+lloys of magnesium and aluminium should never be used in the cargo tank area, due to their poor

corrosion resistance in such environments.

+s sacrificial anodes these alloys are frequently used. hey are severely attacked by caustic soda.

Methanol will be severely contaminated by magnesium. +ny anodes should be removed before loading

these cargoes. $heck cargoes against ref.,%*& or other information.

here seems to be a belief that +lAMg alloys are spark3proof materials, suitable for tank cleaning

equipment etc. he truth is the opposite/ 5light alloys5 are considerably more prone to cause incendive

sparks than steel ob1ects. Fhen an ob1ect fall3s down into a tank light alloys oxidize at the point of

contact, thus adding a reactive energy to the kinetic energy released. 5=ot5 sparks are created instead of

5cold5 sparks, which are created by steel ob1ects falling down. +s a flammable mixture requires a certain

minimum amount of energy to trigger off an explosion it follows that 5light alloys5 are considerably more

dangerous. herefore/ do away with tank cleaning gear of light alloys?


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n this connection it can be mentioned that so3called spark free tools are no longer particularly

recommended. ests have shown that steel tools are equally safe, see ref %G&.

4.0! Tan" #oatings

+ modern chemical tanker has all her cargo tanks coated unless they are made of stainless steel. he

main reasons for coating are/ easier cleaning and less risk for cargo contamination. he durability of

properly applied and maintained coatings may be ten years or more. 'n the other hand one mistake in

cargo selection may totally ruin a coating. t is a matter of knowing the limitations and possibilities of

each type,or even of each make, of coating. =ere the chemical build up of coatings shall not be

elaborated, only the physical properties as regards resistance and application. Hvery paint

manufacturer has his own resistance list stating approved cargoes, temperature and time limitations etc.$ontact the maker if in the slightest doubtE mistakes may turn out to be very costly. Many coating

manufacturers give some sort of guarantee for the first two years after application.

Hpoxy coatings generally possess a good resistance against alkalies, seawater, wine, vegetable oils,

crude oils, gas oils, lub oils, 1et fuels, gasoline and also weak acids %as in free fatty acids in vegetable

oils, but acid value should not exceed 4"3!"&. Hpoxy ha s limited resistance against aromatic

hydrocarbons %5solvents5 such as benzene, toluene&, certain alcohols %e g methanol&, ketones %acetone&

and some esters. Hpoxy is sometimes indicated as resistant also to stronger acids. his may be correct,

but as an applied coating one must count on 5holidays5 in the film, thus making epoxy unsuitable forreally corrosive liquids.

Hpoxy coatings which have been stressed beyond their chemical resistance with strong solvents tend to

softenE test with your nails. n such a case the coating must be given ample time to 5weather out5

trapped solvents and recover its hardness before being sub1ected to cargo or water again. o not try to

speed up the recovery by application of heat? he top skin of the coating may then first harden, leaving

trapped solvent underneath, with flaking as a consequence. >entilate with a good turbulence in all

corners of the tank. =ardness of epoxy coatings can be established by means of a standardized test

using pencils of different hardness as a reference %Sw standard SS *9! *9D&.

+dhesion of a coating to the steel is also reduced if it is overstressed by a cargo of strong solvents. here

are standard test methods for the determination of adhesion by means of glued3on tablets, which are

then pulled off with a recording of the necessary force.

Hpoxy coatings should normally not be heated above ;" 3%9"& degr.$ during tank washing, steaming etc,

uring the loaded voyage lower temperatures should be kept.

Hpoxy tar coatings. are made up from epoxy with an addition of coal tar. hey are excellent against

seawater and crude oils but should never be used in chemical tankers, 0ight hydrocarbons of moderate

solubility such as 1et fuels, gas oils, gasoline may cause the tar to leak out, which may contaminate the

cargo.

Iinc silicate coatings particularly those of inorganic type, are very resistant against strong solvents and

normally tolerate higher temperatures than epoxies. ypical products are/ aromatic hydrocarbons

%benzene, xylene etc&, alcohols, ketones. Jet fuels may suffer zinc 5pick up5 from the coating to anextent which is considered a contamination. herefore/ check with shippers requirements. Iinc silicates

are not resistant against acids or alkalies. he p= value of the cargo should be within the range #, # 3*",

# %neutral p= D, "&. his means that some molasses %slightly fermented 3 low p=& may attack zinc

silicates, as well as high contents of free fatty acids in vegetable or animal oils/ Iinc silicate coatings

may under such circum stances cause zinc pick up into the cargo. hey are therefore not normally

suitable for edible oils for human or animal consumption. Remember that the contents of free fatty acids,

and thus also the aggressivity and zinc pick up, may increase during transport. $ertain coatings have

-overnmental approval for edible oils, check for p=3limitations in such cases.

Iinc silicates are not suitable for long time exposure to seawater, the life span will be unduly reduced.


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+fter carriage of molasses in zinc silicate coated tanks a thorough cleaning should be carried out as soon

as possible. Sour cargo remains on the tank bottom may damage the coating.

Iinc silicates are only partly resistant to chlorinated compounds %e g carbon tetrachloride, ethylene

dichloride, trichlorethylene&. f the water content is high hydrochloric acid may develop, which will attack

the coating. n a similar way hydrolyzable hydrocarbons such as esters, acetates and halogenated

compounds may .attack the cargo. f, however, the product is guaranteed dry and the cargo tanks and

piping are completely drained and dried these products can be carried.

+lkaline tank cleaning agents %caustic& should never be used in zinc silicate coated tanks. $onsiderable

damage can be doneCin one single cleaning operation. Iinc silicates stand well up against other cleaningagents such as 5solvent cleaners5 and 5emulsifiers5 unless they have alkaline additives/ $heck first with

the maker of the cleaning product?

f a zinc silicate coating has been attacked one can often observe a thin layer of white dust on the

surface, or the coating gives a porous appearance. nform the 'wners at onceE it may be that the last

cargo was off specification and caused the damage.

2henolic resins are a recent addition to the family of tank coatings. hey have a wide resistance list

including strong solvents which the epoxies do not tolerate3 +t the same time the phenolics accept aboutall of the products that zinc silicates tolerate. his type of coating is likely to gain further application on

board.

2olyester coatings have poor resistance to solvents but are fairly resistant to weak acids and alkalies.

hey are not used on board in chemical tankers to any extent.

Maintenance of tank coatings means, above all, not to sub1ect the coatings to non3permissible cargoes.

$heck with maker:s recommendations. 0imitations as regard p=3values, max temperatures and max

permissible storage time on board must be followed. 0et epoxies regain their hardness if softened.

-enerally it is not worth while to recoat an epoxy coated tank on top of an old coating, the risk for a poor

bond is too great. Minor damaged areas can, with a certain degree of success be recoated. he area

must first be degreased well. he area should then be ground to a bright steel finish with a rotating

grinder, grain 9" to *4", with an even transition to the coating. * 3 4 coats of primer plus 7 3 ! finishing

coats may be necessary in order to build up the proper film thickness %4""37"" microns&. he tank wallmay have to be warmed up %preferably from behind& in order to insure that there is no risk for

condensation on the surface. f possible the, tank wall should be warmer than the tank atmosphere. (or

application of coating on a whole tank the steel bulkheads must be properly sandblasted %non marine

origin sand&, normally to the internationally known standard Sa 4 *AK.

4.0$ Ru%%er lining

n recent years a number of ships have been fitted with rubber lined tanks, for the transport of

phosphoric acid,

waste acids and hydrochloric acid.

he mild steel surfaces to be lined should be prepared by grinding away rough weld beads, surfacedefects, weld splatter etc. hen comes sandblasting to 5bright metal5 %Sa 4 *A4 3 7&, priming with a

rubber glue and an application of a contact rubber glue. hereafter the uncured rubber is applied in wide

sheets and pressed on by means of hand rollers. he rubber is usually !3; mm thick with reinforcements

where mechanical wear may occur, such as hatches etc. he rubber is vulcanized by heating with steam

or hot water for a period of *#37" hours. Synthetic rubbers may have a curing accelerator added and will

vulcanize at normal ambient temperature %4"37" degr. $& in a few weeks.

8atural rubber has been used in ships for phosphoric acid. But chloroprene %neoprene& synthetic rubber

is a more usual choice on board. t has a much better resistance to sun radiation, oils and ozon,


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$hloroprene is, however, more expensive and is somewhat more difficult to apply. $hloroprene is

resistant to strong acids %not sulphuric acid& and strong alkalies such as caustic soda. n some cases

chloroprene lined tanks have been used for backhauls with fuel oils. his rubber will, however, not

tolerate light hydrocarbons. Butyl rubber has a very good chemical resistance but is stiff and hard to

apply.

-reat caution must be exercised so that the rubber will not be sub1ected to mechanical damage due to

falling ob1ects, tools etc, Rubber lined tanks should have a minimum of fittings such as brackets, ladders,

internal piping etc which can create weak spots.

Steel piping, including bends, can be rubber lined. he pipe diametres should be chosen somewhat

liberally in order to keep liquid velocities relatively low. Membrane types of valves as well as pumps canbe lined with hard rubber. +s heavy wear may occur on these parts the use of stainless steel is,

however, recommended. he advantage of having a pure rubber lined system with regard to a possible

high contents of chlorides in the product will then, however, be lost, see !."4.

Rubber linings are tested for pores and defects by means of a high voltage tester at *" """ >

%chloroprene& and 4" """ > %natural rubber&. o check the progress of curing or aging a Shore

urometer is used.

Shore tanks are sometimes lined with2>$ %poly vinyl chloride& sheets glued into place. But thistechnique does not seem to be sufficiently developed for use on board ships.

!."D -askets and packing

Fhen 2(H %polytetrafluor ethylene, trade names/ eflon, (luon, =ostaflon (& came on to the market a

few Lears ago it solved many gasket problems. his material is resistant to all likely chemical cargoes

and all common temperatures on board. he 2(H has some very typical properties/ it is expensive, has

a low frictional resistance and a low thermal conductivity, does not adhere to other materials and yields

or 5creeps5 when under pressure.

2(H as a gasket in flange connections should either be reinforced %asbestos or glass fibres&, contained

in a grove %maleAfemale& or used as a relatively thin envelope around a core of more conventional gasket

material. 5$reep5 can then be controlled. 5Blue5 asbestos generally gives better chemical resistanceagainst acids %p= *3!& than 5white5 asbestos. n 5envelope5 gaskets the cargo comes into contact with

2(H only, which is an advantage.

t is an advantage to use 2(H packings in pump and valve spindle gland boxes. But remember that the

bottom clearance between spindle and housing may have to be less than usual as the packing will have a

tendency to creep out this way.

+lthough 2(H will solve most problems one must remember that common, and cheaper, materials will

often suffice. f an existing oil tanker is to carry strong solvents %e g aromatics, ketones etc& flange

gaskets of asbestos 3 reinforced synthetic rubber will usually be acceptable. (lange gaskets of synthetic

rubber3asbestos will normally stand up against strong solvents, alcohols, strong alkalies %caustic& and

acids. f in doubt, check with the maker. Hxpansion glands in cargo piping and valve spindle glands,however, should be repacked

with 2(H3asbestos packings.

Rubber gaskets are not suitable for oils or solvents. Rubber is suitable for phosphoric acid. $hloroprene

rubber %8eoprene& is resistant to caustic soda and ammonia solutions.

$arbon fibre spindle packings are sometimes used in high speed pump glands. hey are expensive but

have the advantage of low friction, chemical inertness and high thermal conductivity.


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8itril and fluor %>iton& rubber have a very good chemical resistance, see 7. "4, to strong solvents as well

and are used particularly in '3rings for stem seals in valves.

See also resistance table in $hapter 7. "4.


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! &IRE 'R(TECTI()

(ire prevention is one of the most essential safety measures on board a chemical tanker. iscipline is

needed in the daily routines. Fatch out for obvious things such as/

- look out for all leaking flanges, valve and pump glands

- keep pump room bilges free from cargo spills

- see to it that steam pipe insulation does not get soaked with oil or cargo

- check cargo tank and pump room atmosphere for cargo vapours before starting any work there

- do not steam a cargo tank simultaneously with washing

- use flame3proof lights in cargo tanks and pump rooms

- check pump glands and bearings regularly for heating

- cigarette lighters in the cargo tank area to be forbidden- observe cargo vapour release during loading and take action if vapours reach accomodation areas

- check cargo pump glands for heating

- take active part in safety 3 drills and get acquainted with all the safety equipment

- instruct newcomers on board on safety procedures

- get to know your ship, cargo handling gear etc.

he formal responsibility for surveillance of the fire fighting equipment normally rests with the respective

8ational +uthority, but is in some cases delegated to the $lassification Society. t rests with the 'wner

and the Master to keep all equipment in order and to provide additional means for any cargo not coveredby the intent of the Rules of the 8ational +uthority. he M$' 5Bulk $hemicals $ode5 ref %4#&, $hapter

, see +ppendix ;, gives some general guidance on necessary equipment on board and indicates the

best means for extinguishing fires for a number of cargoes. Similarly the $S anker Safety -uide ref %t&

gives more detailed information on the choice of extinguishing method to be used for the individual

cargoes

Several methods of extinguishing fire can be used. Fithout going into more complicated details let us list

the most important aspects of the matter of fire fighting in the cargo area on chemical tankers/

!.01 *ater e+tinguising

+ll ships are fitted with means for fire fighting with water. +lthough not ideal, water can be used on fires

in a ma1ority of chemical cargoes, the advantage of course lying in its abundant supply. Fater is,

however, not very effective in extinguishing fires in very gassing cargoes such as naphta, gasolines orliquified gasesE it may, however, then be used as a cooling medium in connection with dry powder or

other methods of fire fighting in order to avoid dangerous 5back flash5, see #. "7.

Fater should be applied to the base of the fire by means of water fog 1ets, water pressure preferably not

lower than

G kpAcm 4. he fog serves as an excellent heat radiation shield in front of the. operator. 8ever direct a

solid 1et of

water on to a burning liquid surface, the effect will only be that burning liquid is splashed around,

thereby making the fire bigger. :Fater fog shall be applied with a strategy of chasing the fire succesively

away from the operator. he fog may be swung from side to side to cover a wide front of attack. o not

apply water fog on top of foamE it will cause the foam to disintergrate and may possibly in so doing ex3

pose the surface of the flammable cargo to the risk of a back flash.

t is a good practice to have water hoses with fog 1ets connected to the fire main on deck during cargo

handling.

he M$' $ode ref %4#& advices against water for most products in the relevant 5Summary of minimum

requirements5. his list, however, is meant to emphasize that other extinguishing media are a first

choice and are to be provided on board.

o not hose water into conc sulphuric acid, an eruption of liquid may occur?

!.02 &oam e+tinguising

(oam extinguishing is provided on many chemical tankers and ona ma1ority of modern large crude oil

carriers. 'f

ll th ti i hi th d i th M$' $ d f i f d b t th f d d i ll


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gases penetrate the foam and burn on top of it. (oam is a good method for fire prevention/ a deck area

or a free cargo liquid surface can be protectively foam covered if there is a danger of fire. f a liquid

surface is to be foam covered/ direct the foam onto a bulkhead or other vertical surface and let it spread

from there and float out to cover the entire liquid surface. he foam operator may have to be shielded

against heat radiation by means of a water spray.

Medium density foam %waterAair ratio abt */4""& is used in enclosed spaces such as pump rooms.

Medium density foam can be produced very simply in fixed distribution 1ets under deck, in e g a pump

room, by using the e1ector power of the water stream to draw air into the water foam mixture. Medium

density foams are intended to cover the bottom part of a compartment. he installation is very simple

and relies on starting the fire3pump only.

0ight foam %waterAair ratio */4"" 3 */*"""& is only used in enclosed spaces such as engine and pump

rooms. t is usually produced by means of a water driven fan which blows up the foam mixture. he

foam is intended more or less to completely fill up the compartment in question.

0ight foam is sometimes used as a preventive blanketing medium when 5hot work5 %e g welding& has to

be carried out in a cargo tank, which may not have been possible to clean perfectly. he whole tank

bottom is then foam covered, leaving only the work location free. 'f course the tank has to be

guaranteed gas free before starting hot work. Similarly neighbouring tanks can be protected before

welding is started on bulkheads.

5.03 Dry powder extinguishing

Many new chemical tankers use dry powder extinguishing ry powdersystem as the main fire fighting

method in the cargo tank extinguishing area.

here are to be found centralized powder systems with possibilities of discharging several thousand kgs

of powder. Release boxes and hose f eels are strategically located on deck so that any point can be

reached by two hoses, each being usually max 4# m length. 'n smaller vessels self3contained powder

containers of *"""37""" kgs are located in small deckhouses.

+s mentioned above the M$'3$ode accepts dry powder as equivalent to foam. ry powder has decided

limitations, which are explained below.

he extinguishing effect of dry powder originates mainly from an inhibiting effect on the combustion. he

smothering and cooling effects are small.

ry powder has a particularly good extinguishing effect on larger volumes of burning gases and strongly

vapourizing liquids, as compared with other means of fire fighting. But it has virtually no cooling effect

on any steel, cargo liquid or other matter that has become heated from the fire. 'nce the flames have

been thrashed out with dry powder there is a great risk for a fire back flash which can be more violent

than the original fire. +t a ma1or fire therefore, the fire area should be cooled down with water fog as

much as possible prior to application of powder. Fater cooling must be continued after the flames have

been extinguished f a fire can be fought immediately after its outbreak and only little heating has

occurred one should of course immediately start with dry powder, not awaiting water fog assistance.

$ommon types of dry powder have a tendency to break down a foam layer. herefore the two methods

should be avoided being used together. Some new powders are claimed not to have this deteriorating

effect on foam.

+lways place two dry powder extinguishers at hand on deck aft of the cargo manifold, when loading

Aunloading.

!.04 -Total looing- system or pump rooms. Inert gas or ire prote#tion

Many tankers have a3$'4. total flooding5 system for the cargo pump rooms. his is a most effectivemethod for extinguishing a fire in a closed compartment. $ertain dangers, however, are involved

- make sure the room has been evacuated before admission of $' 4: 8o one will have a chance of

i th h b d itt d


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o ensure safety on board one must adhere to the following points/ 6nowledge, training and strict

routine. 6nowledge of the cargo to be loaded, knowledge of your ship and her equipmentE training in the

use of safety equipment on boardE strict routines in cargo handling, tank cleaning, strict routine in

command and reporting, strict routine in using protective clothing etc.

$.01 'oisoning an oter ris" it #argo #onta#t

ifferent chemicals affect the human body in many different ways. he sub1ect is comprehensive and a

deeper insight in to this is beyond the scope of this book. + general information and some practical

advice will be given, however. Reference is given to +ppendix,D, being an extract of 5Medical first aid

guide for use in accidents involving dangerous goods5 published by M$', F=' and 0' ref %7;&.

he definition of 5poisonous5 and classification of poisons is not uniform throughout the world. Fe can

define a poison as a substance which is harmful to human beings %or environment&. n the M$' $ode

ref %4#& a substance is classified as a poison if there is a risk of death or serious bodily harm after oral

intake, inhalation or skin contact.

he 5poisonousness5 of a substance is usually expressed in terms of 0 #"3 values, 0ethal ose

%sometimes 0$ #"G 0ethal $oncentration&. hese values are determined by tests with animals and give

the dose, expressed in mgAkg body weight, which kills #" < of the animals in a test series. his figure

gives a rough indication of the degree of toxity of a substance. >arious species of animals have differentsensitivity, which gives some problems in applying the results to human beings. Hxamples of 0 #"

values %pesticides of three categories&/

$lass 0 #" Substance

* *4# mgA kg body weight paration %pesticide&

4 *4#3*#"" 3 AA3 malation 3 AA 3

7 *#""34""" 3 AA 3 bromofos 3 AA 3

n industry the effect of long time exposure of low concentra tion to a substance is of prime concern. he

expression used is 0> %.*hreshold 0imit >alue&, previously called M+$ %Max +llowable $oncentration&.

he 0>3value expresses the concentration of a substance in air, in ppm %parts per 7 million& or mgAcm ,

which must not be exceeded if a daily 93hour exposure over a long period of time shall be harmless.

0>3values are published by 8ational +uthorities and various organizations. he most recognized list of0>3values is probably the one published by +$-= %+merican $onference of -overnmental =ygienists

ref %*#&. he $S3-uide ref%*& also gives 0>3values. he gas concentration can be measured by means

of a portable apparatus described in 7. *" %rager, +uer&. he scale of reference for gas exposure on

board is normally 0> 3values. =uman beings can, however, tolerate a significantly higher concentration

in a short time exposure/

Substance anger of serious 0>

poisoning after %Swedish *GD9&

less than one hour

inhalation

+crylonitrile *"" ppm 4 ppmrichlorethylene 4#" pprn 4" ppm

$arbontetrachloride 4""" ppm 4 ppm

Methanol 4""" ppm 4""ppm

Benzene *"""" ppm # ppm

+ person who is tired or ill is more sensitive than others and should not be asked to work with cargo

handling.

t is a good safety practice to use a breathing apparatus whenever the 0>3value in the atmosphere is

exceeded


11/128

'oisoning

he poison may enter the human body orally, by inhalation, or by skin contact. +fter being absorbed by

the body it may affect certain organs or give a general poisonous effect. 0ately the cancerogene effects

of some industrial chemicals have been noticed. his has led to significant reductions of hereto accepted

0>3 values in many countries. $ertain substances affect the tissues locally as an irritant %cashew nut

shell oil& or cause grave damage to the eyes, skin or mucous membranes %e g strong acids and caustic&.

'ther substances may be absorbed by contact to the skin without local effects %e g nitrobenzene,

aniline&. -ases, in themselves non3poisonous, may be dangerous by their displacement of air %e g

nitrogen as an inert gas in cargo tanks&. he effect of a substance also depends on the temperature, its

solubility in water or %skin& fat, its volatility etc.

$hlorinated hydrocarbons %e g tetrachloride and chloroform& may cause damage to kidneys and liver

after prolonged exposures.

Symptoms of poisoning may appear many hours after contact with the substance. ypical examples are

poisoning from nitrous gases, see 7/"#, and methanol % oral intake&. he reason for the delay being that

the decomposition products rather than the original product are toxic. $ommon symptoms of poisoning

are/ nausea, headache, dizziness, difficult breathing, unconsciousness.

he human body often reacts very differently to acute and chronical poisoning. %+cute poisoning 3 one

contact with the poison, usually high dose or strong concentration. $hronical poisoning 3 small doses or

low concentrations over a long time&. H g benzene causes reduced conscoiusness in acute poisoning but

causes blood and bone marrow damage in chronical poisoning.

$ertain chemicals may cause sensitizing upon first contact. 0ater contacts with the same chemical, even

at lower concentrations, may cause much stronger poisonous effects. ypical in this respect are

isocyanates % e g toluene diisocyanates& where astmathic 3affects on sensitized persons may occur below

0>3 value.

$.02 &irst ai

+ll cases of poisoning, regardless of which kind of poison, require certain basic common methods oftreatment. +dditionally, a few particular cases of poisonous substances may require antidotes. See

+ppendix D for detailed information on first aid for the various products?

+fter a severe acute case of poisoning involving unconscious ness/ Bring the patient as soon as possible

out into the fresh air. Rescue personnel must not take undue risks themselves, don:t therefore rush

down into tanks or pumprooms where vapour may be present 3 oo many fatalities have occurred with

people who have not realised that a breathing apparatus was needed. (irst, keep the breathing passages

free %prevent the tongue from falling back&. +n unconscious person should be laid on his side, face down,

with one arm and one leg bent to prevent him from rolling over. 0oosen the clothes around the neck and

waist and remove false teeth, see fig 7G.


12/128

Mouth to mouth artificial breathing may be necessary %avoid mouth to mouth contact with severely

poisoned or contaminated patients as the rescuer may then be at risk&. =eart massage may be

necessary. See +ppendix D for detailed advice.

f the patient:s condition does not apparently involve immediate risk for his life the following measures

are

applicable/

+fter inhalation/ he patient to be brought into fresh air with as little effort and strain to himself as

possible, @ndue strain on the patient may affect him adversely later. Hven if the patient is free of all

symptoms he should be kept quiet and rest as some gases have delayed effects %nitrogen oxides in

combustion inert gas, nitrous gases&. 6eep the patient in a comfortable inclined sitting position %ifunconsciousness does not prevent it&.

+fter splash in the eyes/ mmediately wash the eyes in gently flowing water, in a washbasin, in a 1ug or

a special plastic eye bath with a bottle of water, see fig !". he eyelids may have to be forced open and

the patient told to move the eyes in order that all parts will be thoroughly rinsed out. Fashing out the

eyes may be very painful and pain3relief eye drops can be used. $ontinue to wash for another *"3*#

minutes. n case of acids or alkalies %caustic& the washing must be repeated for a couple of minutes

every *#37" min for the next !3# hours, preferably with a 8a$l %table& salt solution %", D 3 ", G


13/128

+fter swallowing/ f the patient is unaffected give him a couple of glasses of liquid to drink for dilution of

the poison, preferably water %never any alcoholic drink&. +fter intake of alkalies %caustic& a drink of

lemon 1uice can be given, or a * :D; solution of acetic acid. f available give medicine coal which

absorbes a number of poisons and which in itself is harmless %7"3;" crushed coal tablets or coal

granulate in some water&. Make the patient vomit, 8', however, in the case of corroding %acids or

caustic& products or oil products like kerosenes, gasoline, 1et fuels, when vomiting may be

life3threatening. ilution of the stomach contents, however, is important. n case of doubt/ do not cause

the patient to vomit.

>omiting can be caused by giving warm salt water %one table spoon of salt to one glass of water&. henby putting two fingers down the throat and moving them about gently vomiting usually follows. he

procedure is described in ref %7;&.

+fter certain products antidotes should be given, see advice in ref %*& and %7;&. he most likely cargo for

which an antidote may have to be used is acrylonitrile %5+85& and acetone cyanohydrine. he remedy

then is to douse some clean rag with an ampoule of amyl nitrite from the medicine kit and hold it under

the patient:s nose # times with *# s interval.

'xygen should be administered in cases of weak breathing. t is an M$' $ode ref %4#& requirement to

have oxygen resuscitation equipment on board.

n cases of poisoning medical advice should be sought as soon as possible, e.g through the various

radiomedical5 services. Fhile at sea also contact the shipper, who usually possesses a good knowledge ofthe product and its after effects.

$.03 Cargo inormation to sip5s personnel

he following advice is more or less obvious but is listed for the sake of completing the above

information.

t is a clear responsibility for the 'wner, the master and the officers to inform their personnel about thecargoes to be carried, safety procedures etc and to arrange for the proper training.


14/128

nformation should be given partly in the form of written notices combined with informal meetings with

the entire crew present when new cargoes are to be loaded or when unexperienced personnel are to be

signed on. +mong other things the following information should be given/

3 $argoes to be loadedE their characteristics as regards handling, pumping, toxity, corrosiveness, first aid

etc

3 the cargo loading plan to be posted in places where it will be clearly seen by everyone on board and at

the accomodation ladder, when in port.

3 2ost cargo information cards for products to be loaded or are contained on board. 'ne suitable type ofcard can be found in ref %i&, with examples in fig !7. +lso ref %!& and %#& show suitable information. (or

5new5 products ask the shipper for safety brochures and leaflets. See also ref %7&, %*4&, %*7&, %*;&, %*D&

and %49&.

3 the personal safety equipment to be used by those involved in cargo handling, pumping, sampling etc.

C6EMICALS 7 (8R SA&ET () (AR9

Make sure that you/

3 use goggles, gloves, oilskin or apron and rubber boots when operating cargo gear.

3 use more extensive personal protection when needed or when ordered to do so. See separate

instructions for various products.

3 know what products are carried on board and that you are familiar with their respective safety

measures. Study safety

instructions and ask the $hief 'fficer?

3 know where eye flushing bottles are located %pump3rooms and on deck midships&.

3 now and practise how to flush your eyes with water MMH+H0L in case of accident. Hyelids mayhave t; be forced open to

permit proper flushing?

3 know where safety showers and water rinsing hoses are located, in pumprooms and on deck.

3 use breathing apparatus in tanksApumprooms which have not been declared safe or when ordered by

officer on duty.

Breathing apparatus shall be available for immediate use on deck when loadingAdischarging.

3 never enter dangerous compartments unless ordered by officer on duty. 2roper personal protection

should be used and

personnel should stand by.

3 know where the oxygen resuscitation apparatus is located.

3 take part in the monthly safety drills.

(ig !4 Hxamaple of a safety poster

3 =ave available on board litterature on chemical cargoes, medical advice etc,


15/128

3 nform in particular if the cargo to be loaded has an odour threshold which is higher than the

0>3value,

see ;. 'f, and that danger cannot always be sensed in advance % e g allyl alcohol, carbon tetra

chloride,

etylene dichloride&.

3 -ive information that most vapours are heavier than air and have a tendency to accumulate in low

spaces.

herefore work below gratings in pump rooms, cofferdams, pipe tunnels etc is extra dangerous.

3 8ever take work clothes into your cabin? Soiled clothes must be washed before being used again or in

the

case of toxic products, destroyed.3 Fash your hands before meals?

3 -ive information about fire fighting methods for each type of cargo on board.

3 -ive information if the cargo is water3reactive or reactive to other cargoes on board. -ive information

on

segregation required.

3 (or some very toxic cargoes mouth to mouth artificial breathing might be dangerous to the rescuer %e g

acrylonitrile, acetone cyanohydrine&.

3 nformation must be given particularly if the cargo danger lies primarily in vapour inhalation %e g

acrylonitrile, trichlorethylene& or skin contact %e g phenol, caustic soda, sulphuric acid&.

3 State where eye washing bottles are located %deck office, at cargo manifolds on deck, in pump rooms,

on fore

deck etc&.

3 nsist on that nobody should work with cargo gear without anyone standing by. =ave people report

when

going to and returning from pump rooms?


16/128

3 -ive information if any cargo is so toxic that an escape breathing mask must be used in an emergency.


17/128


18/128


19/128


20/128

$.04 Sip inormation to sip5s personnel

t is essential on chemical tankers that everyone knows his ship:s safety precautions thoroughly. +lso the

masterAchief officer must assume responsibility for this. 8ewly signed on members of the crew should be

informed about the following items and be shown around the ship to get detailed knowledge/

3 -et to know pump rooms, cofferdams, pipe tunnels, emergency exits.

3 he manouvering and emergency stops for cargo pumps and cargo valves.

3 Bilging of pump rooms.

3 2ump room ventilation incl information on necessary pre3ventilation before entry and emergency stop

of fans in

case of fire.3 Safety showers3%in pump rooms, fore and aft on deck&,

3 -as warning equipment incl the sounding of alarms %fixed and portable&.

3 0ifting gear incl stretcher to get an unconscious person out of a 2ump room.

3 $argo tank vapour vents, incl opening, prior to cargo fillingAdischarge.

3 $argo sounding equipment.

3 0ocation of fire fighting equipment incl detailed instructions for operating them.

3 2ortable fire %powder& extinguishers placed at hose manifold.

3 Fater hoses to be connected amidships ready for washing off cargo spills %if considered proper under

thecircumstances&

3 $argo tank arrangement.

3 $argo piping system incl means of segregation.

n fig !4 a set of safety instructions for a particular vessel are shown as an example. Make one which

suits your ship?

(or the sake of record it may be noted in the deck log when cargoAship information has been given.

$.0! Sae pra#ti#es en anling #argo

Most of the items listed below have been briefly mentioned in the previous text. he list can be used,

however, as a check list for some general practices and common safety routines/

Before loading Aunloading/

3 =ave cargo tanks to be loaded well ventilated and checked for any toxic vapours so that tank inspection

can

commence without any danger or undue delay.

3 2ortable %dry powder& fire extinguishers to be placed on deck ready for use. ake off covers etc and

make other fire

fighting equipment on deck ready.

3 $heck cargo hoses to see that they have not deteriorated, that flange connections are intact, that there

is an

electrical bond between hose flanges and that the working pressure for the hose is marked on it. f

there is anydoubt about the hose:s condition, find out when the hose was last pressure tested, see 7. "4. +fter

connection of the

hose to the ship:s manifold the. flange should be pressure tested for tightness with air at ;3*"kpAcm 4

%shore valve

closed&. Fith corrosive and toxic cargoes a protective cover should be placed over3the hose flange

connection. +

drip pan should also be there.

3 Hstablish communication routines with the terminal operators regarding flow rates, emergency stops,

topping up,


21/128

general alarm etc.

3 6eep unauthorized people away from the cargo deck and hoses. $heck that vapour releaseAadmittance

to the cargo

tanks is unobstructed %2A> valves moveable, lids opened, flame screens unclogged etc&.

3 6eep hatch lids closed except when taking ullages, sampling etc.

3 See to it that everyone engaged in cargo handling is wearing the correct protective clothing %depending

on whether

there is danger to the skin on contact or inhalation of vapour.

3 +void getting the blast of vapour in your face when taking ullages during loading. o not stand

5upwind5 or

5downwind5 of an ullage hole but stand beside it with the wind across your face.

3 6eep pump rooms ventilated with fans running during cargo transfers.3 6eep moderate loading rate during the first phase of cargo transfer to an empty tank %not necessary

with

inerted tanks&, particularly with petroleum products of the type kerosene, 1et fuel. he liquid velocity

should

be kept well below mAs in the cargo piping until the liquid covers bottom framing or about ", # m

above

bottom. %Risk for static electric charges and incendive sparks. See ref %G&&.

* mAs means for a !N pipe 7" m.7Ah 3 AA 3 3 AA 3 9N 3 AA 3 **! 3 AA 3

3 AA 3 3 AA 3 *4N 3 AA 3 4#9 3 AA 3

3 he final ullages should not be taken before 7" min after loading is finished if conductive tape is used

%when

possible static electric charges are likely to have been dissipated&. 8on3conductive tapes to be

preferred.

3 8ever go down into a pump room without reporting to someone on duty when leaving and on returning

3 8ever work alone in confined spaces?

3 =ave breathing apparatuses on deck ready and available when handling toxic cargoes.

3 Remember that an explosimeter only indicates the risk for explosive conditions 3 toxic conditions may

arise

at far lower concentrations than detectable by an explosimeter instrument. @se also a toxiometer forhealth

readings. See 7.*" and ;."*.

3 8ever wash and steam a tank simultaneously. Many explosions have proved this to be a dangerous

combination, electric charges are a likely reason. t might be dangerous to enter a tank containing

oxidizing

vegetable oils %e g castor seed oil, cotton seed oil, ground nut oil, linseed oil& during the last phases of

discharge. hereare indications that conditions with lack of oxygen in the tank atmosphere may

develop. @se

a breathing mask with fresh air supply or forced ventilation.

'ne 5half3mask5 and one emergency mouthpiece with nose clamp is shown in fig !9. he maker will be

able to advice on types of filters for the cargoes in question. (or escape purposes a better equipment ishandy air bottles with masks for short time use.

3 +ir compressor for recharging of breathing air bottles %4""37"" atm& should be standard equipment on

chemical tankers.

Below is listed suitable equipment for operational personnel for various typical cargoes and operations on

board/


22/128

a& 2roducts involving little or no danger upon skin contact, moderate vapour toxity and relatively high

volatility %low boiling point& as e g/ petroleum products, petroleum naphta, toluene, benzene, xylenes,

methanol, acetone, methyl ethyl ketone, gasoline, styrene,

@se/ Rubber boots, gloves.

=ave in your pocket for use / %when taking ullages, sampling etc& 2lastic goggles

+ breathing apparatus %compressed air type 4"" atm& should be kept ready for immediate use if sudden

entry into a gas3filled pum3proom should become necessary. Hye washing bott les available on deck and

in pump rooms. Hxplosimeter and toximeter available.

b& 2roducts with a strong corrosive effect on human tissue, moderate or low vapour toxity as/ sulphuric

acid, caustic soda, phosphoric acid %eye danger primarily&, acetic acid. @se / -oggles or face shield,

oilskin or apron, rubber boots %trousers outside&, long cuffed rubber gloves, helmet. Hye washing bottlesavailable on deck and in pump rooms

c& 2roducts which involve great danger upon skin contact %poisoning& and high vapour toxity as e g/

phenol, acrylonitrile, acetone cyanohydrine, allyl alcohol, aniline, chlorosulfonic acid. @se on open deck

%as a minimum&/ skintight fitting goggles or face shield, oilskin, rubber boots %trousers outside&, long

cuffed rubber gloves %tucked inside 1acket sleeves&, helmet.

=ave in your pocket for immediate use/ -as mask %full mask or emergency mouthpiece with nose

clamp&. Hye washing bottles available on deck and in pump room . +t least two breathing apparatuses

%compressed air types& should be kept available on deck for immediate use. oximeters available ondeck. Fhen handling hoses or entering contaminated areas/ use full protective suit, preferably of

pressurized type with hood and permanently attached rubber boots.

he M$' Bulk $hemicals $ode ref %4#& gives some general information on the amount of and the type

of personal protecti;n to be provided on board. (or the purpose of being a check list is given below what

might be considered the minimum amount of equipment on board a chemical tanker of 7" """ tdw.

ndicated, in brackets, is the M$'3$ode minimum requirement %where given&. +n 5x5 means

5sufficient5/

8umber of

; %7& Breathing apparatus, compressed air type, with air bottles % in addition to S'0+S fire

fightingequipment& min. 4" minutes action time.

* Compressor with fittings etc. for charging of air bottles for breathing masks.

*4 +ir bottles to above %D l at 4"" atm or ! * at 7"" atm&, as reserves.

7 Breathing hood with filters and 4 x 7" m hose.

7 %7& 2rotective suit, chemical resistant, overpressure type with hose connection. Rubber

boots attached

with chemicals resistance list.

; %7& 2rotective suit, chemical resistant, rubber boots %attached with

chemicals resistance list&

7" %x& 'ilskinN, chemical resistant.

4"p %7& 0ong rubber boots.

*" %7& +pron

7" p %7& -loves, long, sleeved.

#" p %7& -oggles, plastic, tight fitting.

*" p %7& (ace shields.

7 %7& Steel cored rescue line with belt and hook.

*4 %7& Safety lamp.


23/128

4 %4& -as indicator for flammable gases %double scale&, with calibration unit.

4 %4& 'xygen indicator.

4 %4& -as indicator for toxic vapours %with liberal supply of detection ampoules for likely

cargoes&.

*" %x& Hye washing bottles.

* %*& 'xygen resuscitation equipment.

%all on %all on -as mask for emergency use, with filters for cargo vapours %if very toxic and volatile

cargoes are to be

board& board& carried&.

%x& %x& +ntidotes. See ;."4 and ref %7;& re cargoes.

%i& %*& Stretcher suitable for use in pump rooms etc %Japanese type&

%x& %x& Shower %on deck and in pump rooms&

%x& %x& $argo and medical information %e.g ref %*&, %4&, %!&, %#&, %*;&, %*D&, %44&, %4#&, %7;&&.

8B/ 8itrile rubber %gloves& is not resistant to acrylonitrile and should not be used with this product.

: TA); CLEA)I)

$leaning of tanks is usually the responsibilty of the ship. See paragraphs 9 and G in 5BM$=HM>'L5 in+ppendix 9.

ank cleaning and the cleanliness involved have different standards depending upon the previous cargo

and the cargo to be loaded. But the matter can be still more complicated, as cleanliness for one and the

same product may vary, depending on who the receiver is and for what purpose the cargo is finally

intended. Hxamples/ glycol intended for cosmetics or pharmaceutical purposes requires cleaner and

completely odourless tanks than does glycol intended for antifreezesE caustic soda for making paper is

more sensitive to iron contamination than caustic soda for the aluminium industry.

t must be mentioned first that the ma1ority of cleaning op 3rations on board chemical tankers are being

carried out by means of water washing only. (urther chemical cleaning is required for only a limited

number of cargoes, but these cases may be very important.

'ne must take into consideration the nature of the previous cargo and the cargo to be loaded, time

factor, available equipment and cleaning chemicals etc. n +ppendix # it is stated the necessary degree

of cleanliness for a number of products, in line with what cargo surveyors normally require.

-enerally speaking one should use mechanical tank cleaning methods, that is usually washing with

water, before applying more expensive methods involving chemical cleaning agents. he most

expensive, and least safe, method is manual cleaning, which should be kept to a minimum. Manual work

should preferably be reduced to inspection and possibly to a final drying up of washing water only.

t is important to drain the tanks as much as possible in order to deliver all cargo and to reduce pollution

of the seas to an absolute minimum. his will now be even more important with the anti3pollution

$onvention of *GD7 %see *"."*&.

Hxamples on measures on how to obtain the best possible cargo stripping/

3 ue regard to ship:s trim and heel.

3 >iscous cargoes may first be stripped from the various tanks to one tank near the pump room and

from there

be pumped ashore.

3 6eep the cargo temperature sufficiently high so that the cargo drains also from remote corners of the

tanks,


24/128

especially in cold climates.

3 Faxy deposits under the heating coils can sometimes be melted out be means of filling with water and

then

applying heat to the coils.

3 Sometimes steaming is allowed during discharge of molasses, which facilitates draining of molasses

from

the bulkheads.

3 >egetable oil tanks may in the last phase of discharge be recirculated and hosed down with vegetable

oil

taken from the cargo pump delivery side %see warning under ;. "#&. Similarly phosphoric acid can be

recirculated to loosen sediments on the tank bottom.

3 rain cargo piping to shore. t is useful to have a small stripping pump with #" mm delivery line to thehose

connection for delivery of contents in the cargo piping to shore.

3 Before loading sensitive cargoes/ mudboxes, valve bodies and pump housings must be drained by

opening the

drain plugs %with due regard to personal safety&.

he following text is intended as a general guide and will give some practical examples on problems and

methods. Reference is given to 5ank cleaning -uide5, ref %*"&, excerpts of which are given in +ppendix

!. See also ref %**&. he information given should not substitute your own or others: good and provenmethods? +lso consult shippers and tank inspectors coming on board.

+nalyze the properties of the previous cargo and take advantage of its 5weak points5, e.g as follows/

3 Fater solubleK f the cargo is reasonably soluble in water then chemical cleaning agents are

unnecessary in most

cases.

3 Fill an increased cleaning temperature cause a beneficial reduction of cargo viscosity and lower

surface tension or

could it cause the opposite/ that cargo residues polymerize or oxidize %5dry5&. 2olymerization and

drying must be

avoided, therefore the first cleaning operation must be carried out cold.

3 s it possible to emulgate the cargo in water or in water with emulgators addedK Make a test on board.

3 Fill the product be affected by alkaliesK $austic soda is a relatively cheap and easily available alkalinechemical.

3 Fill the product dissolve in other easily available products by which the tank walls can be treatedK

%Succesively

5upgrading5 or 5floatation5 methods&.

3 Fill cargo residues vaporize without leaving any tracesK

3 $an cargo remains be safely mixed with the cargo to be loadedK n many cases it is not known what

the next cargo

will be but sometimes this method can be applied.

:. 01 're7 #leaning < asing=

2ractically all cases of tank cleaning start by washing with water. his is mechanical removal of cargoresidues.

his method has a slight emulgating effect %forming minute droplets of cargo suspended in the washing

water&.

he water pressure should preferably be *4 3 *! kp cm 4 with a capacity corresponding to ! washing

machines %9"3*"o m 7 Ah&. he washing water heater should have a capacity of yielding 9" degr. $

washing water with 4 3 7 washing machines working.


25/128

Fhile washing one should simultaneously drain the tank at the same rate in order to assist the cargo

residues in their

flow towards the tank suctions. f not, the residues will have a3tendency to come to rest anywhere on

the tank bottom.

a& 2roducts with good solubility in water %data on solubility in ref %*&, %7&, %#&, %*;&/ 2re3cleaning can

normally be carried out with cold water. Hxamples are/ mineral acids %sulphuric acid, phosphoric acid&,

alkalies %caustic soda, ammoniaApotash solutions&, alcohols %ethanol, methanol, butanol&, acetone. he

more viscous water3soluble products may have to be pre3cleaned with hot water, examples/ glycols,

glycerine, molasses. 8ote/ sulphuric acid must be washed with copious amounts of water to guarantee

rapid dilution and reduce risk of heavy corrosion.

b& 2roducts which are volatile and vaporise without any traces frequently need no tank washin , only

ventilation and possibly steaming of the tank. Hxamples/ acetone, methyl ethyl ketone, hexane,methanol, butanol, propanol, toluol, trichlor ethylene. f water flushing is not carried out/ remember to

drain all cargo lines, pumps etc. raining out cargo may be a difficult process to carry out safely and

therefore water flushing and subsequent draining of the piping may be an advantage. hereafter draining

of water from the piping system can be carried out.

c& Some vegetable oils and animal oils %fatty acids& oxidize and 5dry5 upon application3 of air and heat.

Hxamples are/ castorseed oil, cottonseed oil, groundnut oil, linseed oil, spermoil, talloil. 2re3cleaning

must then be carried out with cold water. 'therwise the residues will dry up and harden and may be

very difficult to remove. (inal washing, however, can be carried out hot, see D. "4.

d& >egetable oils and animal oils of non 3 drying type should preferably be pre3washed directly with hotwater %9""$&. Hxamples/ coconut oil, palmkernel oil, palm oil, tallow, whale oil.

e& 2olymerizing products should be. pre 3 washed with cold water or the tanks should be flooded with

water. =ot water may cause deposits of polymerized material, sometimes very difficult to remove.

Hxamples on such products/ styrene monomer, vinyl acetate, acrylonitrile, vinyl chloride.

f& =eavy oils, lubrication oils, lubrication oil additives, gas oil are normally pre3washed with hot seawater

%9""$& although cold water can also be used.

g& %$rude oil is mentioned as a reference. $rude oil with a relatively high percentage of light fractions

such as +rabian crudes are often pre3washed cold and then hot. f hot water is used the light fractions

are liberated first and then the residue tends to be tougher and more difficult to remove. =eavy crudes,

however, e.g Boscan crude withlittle or light fractions can be washed directly with hot water. &

:.02 &inal #leaning

Method of cleaning to be used depends on both previous cargo and cargo to be loaded. $heck with

+ppendix !

and # regarding cleanliness requirements for cargo to be loaded.

+s a general rule the tanks and piping shall be completely drained of water or residues before loading.

he bottom of the tanks may have to be dried up with rags.

Some cargoes are very sensitive to chloride contamination. he tanks to be loaded with these products

have to be washed out thoroughly with fresh water. Hxamples on such products are first of all glycols

and alcohols %methanol& but also aromatics and acetates. >egetable and animal oils, gasoline, heavier

oils, caustic soda do not normally require a fresh water rinse of the tanks to be loaded.

,a& 2roducts with good solubility in water/ he final cleaning is a direct continuation of the pre3cleaningwith water,

possibly with hot water for viscous products. f sensitive cargoes are to be loaded any odours that

remain must be

ventilated andAor steamed away.

b& >olatile products , as mentioned above, do not often require cleaning after discharge.

c& and d& >egetable oils %drying and non drying& and animal oils are best cleaned by using an alkaline

chemical, usually caustic soda, added to the hot washing water. he oil residues will then be converted

into soap, which is a water soluble product and which will be rinsed off the bulkheads. he cleaning

chemical is consumed quite rapidly if there are un necessary amounts of cargo left. +bout *"" kgs of


26/128

caustic soda are required, counted as a #" < solution, to saponify #" kgs of oil. @sually the cleaning

chemical is added to the washing water in a 437 < concentration of caustic soda %max #


27/128

therefore soon come back. he spray method is more of a symbolic value with regard to the care of the

cargo.

:.04 'ra#ti#al #leaning metos

:.041 Cleaning agent ae ire#tly to te asing ater.

he cleaning chemical is in1ected into the washing water by means of a dosage pump, usually air3driven,

through a fitting attached to the washing pipe on deck. Sometimes the cleaning chemical is added to the

suction side of the washing water pump, thus eliminating the need for a dosage pump. But the dosage

becomes less accurate and the method is more cumbersome in the latter case.

+ direct addition of cleaning chemical to the washing water is quite common, but chemical consumption

tends to be high and its full cleaning effect is not always utilised. *34 hours of washing is usually to be

recommended. he final rinsing being sea or fresh water, depending on the product to be loaded.

:.042 Re#ir#ulation o te asing ater-ives a better utilisation of the cleaning chemical. + mixture of # 3 #" tons of hot water with the

recommended amount of cleaning chemical is made in a cargo tank, a slop tank, a cofferdam or a special

tank for the purpose.he water may be further heated by means of heating coils. + cargo pump may serve as a washing

pump with delivery to the washing line on deck, and then to the washing machines. +nother cargo pump

or stripping pump drains the water back to the containment tank where the cargo residues can be

removed by carefully drawing out the washing water from the bottom.

Fashing should only be carried out on condition that the tank atmosphere is well below 0H0 %lower

explosive limit&. $heck during washing? Fashing should be carried out under inert gas atmosphere if

cargo vapour concentration is above 0H0. here are indications that contaminated washing water may

cause incendive static electricity sparks. his refers in particular to recirculation washing.

he recirculation method can be used with all types of cleaning chemicals. 'ne advantage is that one

can easily incorporate ma1or parts of the piping system in the cleaning circuit. Remember cross3overs

and risers to deck?

(inally rinsing with sea or fresh water.

:.043 Te #leaning #emi#al #an %e applie unilute ire#tly onto te tan" alls.

his method is becoming quite common. he cleaning chemical is sprayed directly onto the tank

bulkheads by means of a high3pressure %portable& pump and a long lance, which the operator can direct

all round the tank. he operator must use protective oilskins, goggles and preferably a breathing mask

too. he cleaning chemical is left on the tank walls for 4" 3 !" minutes. he tank is then washed by hot

water. he process is repeated where necessary until the tank is clean. his method is very effective.

n a similar operation the cleaning chemical is added to an e1ector, which draws it into the steam when

steaming the tank. he tank should first have been steamed thoroughly. +fter steaming with a cleaning

chemical, steaming is continued for a while. (inally rinsing with sea or fresh water. Remember to keepthe hatch lid slightly open to eliminate excess pressure during steaming or sub3pressure after steaming

is finished?

:.043 A loatation meto is sometimes use

(or the final cleaning to achieve a high degree of cleanliness after heavier hydrocarbons such as

lubrication oils, lubrication oil additives and before loading hydrocarbon3 sensitive products such as

methanol. %8ormally a tank is 5upgraded5 to methanol standard via two3three intermediate cargoes of

aromatics &. he floatation method should only be used after first washing with cleaning chemicals. he


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method is then very effective, but it is less effective if cargo residues on the tank walls are of any

appreciable thickness.

he tank is first filled to a level of ", ! 3 ", 9 m from the bottom with a strong non water3soluble solvent,

which is

also reasonably cheap. oluene is usually used. hen the tank is slowly filled with water, thereby lifting

the toluene on top of it. +fter filling, the water is slowly drained again until the tank is empty. he top

layer of toluene is then transferred to the next tank and the process repeated %withthe same water used

again to minimize solvent losses&. he filling and draining can be done with a level change of, say ", # 3

4, " mAh depending on the degree of contaminants on the tank walls.

here have been advanced warnings that this floatation method, although frequently used, might involvehazards as regards static electricity charges in the interface between the two liquids. t is wise to pump

slowly in order not to exceed mAs in the filling pipe, see also ;. "#. he process should preferably be

carried out with the tank inerted,

see 7. "#.

:.04! Steaming it a sol>ent$an also be done as a final cleaning process, after washing with a cleaning chemical. he method will

only be effective for removal of the very last traces of a previous cargo.

(ill the tank with water to 1ust above the heating coils and add a non water3soluble solvent, usuallytoluene or xylene. he water is then heated by means of the heating coils and the solvent vaporises. he

solvent condenses to a certain extent on the tank walls and dissolves minute amounts of cargo residues,

which after draining of the tank can be washed off using water withAwithout cleaning agents added.

he amount of solvent should be of such small quantities that the forming of explosive mixtures in the

tank is avoided. $hoosing 4A7 of 0H0 as a guide one arrives at the following maximum amounts of

toluene/

ank size 4"" m 7 abt *" l of toluen

#"" m 7 3AA3 4# 3AA3

*""" m 7 3AA3 #" 3AA3

(or other solvents the corresponding amounts can be calculated based on the fact that one

grammolecule %Oas many grams as the molecular weight& occupies 44,4 litres of volume at normalatmospheric pressure and temperature.

:.04$ Rinsing it ater is normally te inal #leaning pro#ess,

@nless the cargo remains can be completely vaporised away. Remember that certain cargoes to be

loaded may require fresh water rinsing %risk for chloride contamination&, e g methanol, ethanol and

glycols. Stainless steel tanks shall always be finally rinsed with fresh water, otherwise there is a risk for

tank pitting corrosion, see !."4.

(inally the tanks should be ventilated dry and any water left be dried up with rags prior to loading.

:.0! Cleaning o stainless steelStainless steel can be cleaned with all the methods mentioned above. Regarding removal of tank wall

discolourations see !. "4.

*

D."; Rust descalingN

n the trade of chemicals loose rust will never be accepted upon loading. he rust itself may be harmless

for many

products, e g gasoline, but the rust may contain residues from previous cargoes, which may contaminate

the next


29/128

cargo. -as freeing may also become more difficult if large amounts of rust collect on the bottom of the

tank.

t is sometimes possible to scrape off loose layers of rust. +nother method, sometimes used but

relatively expensive,

is 5electrochemical descaling5. + provisional, but very strong, anodic protection system consisting of

+lAMg strips

is tack welded to the tank interior. he tank is then filled with %salt& seawater for a couple of days. he

anodic alkaline process breaks off rust from the bulkheads and the rust can be washed down. 5'nly5

rust3removal remains. his method is intended for uncoated tanks only.


30/128

? TESTI) (& TA);S A) CAR(ES

he following pages describe and discuss some of the most common tests and checks that are made on

oil and chemical cargoes including testing tank walls for cleanliness.

esting is normally carried out by independent surveyors who, according to local practice or a written

agreement in the charter party, are accepted by shipper, receiver and owner.

f possible one of the ship:s deck officers should take part in the cargo sampling, cargo testing, tank

cleanliness examination etc. =e should make notes and observations on the work of the surveyor with a

view of protecting his party:s interests. t is therefore necessary to have a general knowledge of the

various procedures, without necessarily being able to carry them out himself. n the following text, how3ever, there will be3mentioned tests which are easily carried out by the ship:s staff by relatively simple

means. + small laboratory with a stainless steel sink, a rack for *" 3 4" bottles of chemical reagents, test

tubes %8essler tubes& and a supply of distilled water are an advantage to have on board.

n some remote ports independent surveyors may not be available. his gives the chief officer added

responsibility in following the shipper:s or receiver:s instructions, particularly if he is requested to sign

their protocols etc.

escribed below are a number of tests, which are commonly used by surveyors. Most of the tests are ofa physical nature and are relatively easy to carry out on board. 8ormally the test results do not give any

exact answers as to contaminations etc but have to be 1udged in relation to commonly accepted

standards in industry or agreed values between the parties. (urthermore, the answers are often only

indices of contaminations. n case of any disagreement full laboratory examinations may have to be

carried out. t is then of the outmost importance that the ship secures samples, sealed by an

independent surveyor or by both parties, of the cargo parcel in question for further analysis.

he text below often refers to +SM3standards %+merican Society for esting and Materials&. he

standards are contained in a series of updated books,obtainable through good bookstores or from/

+merican Society for esting and Materials, *G*; Race Street, 2hiladelphia, 2+ *G*"7, @S+.

Similarly +2 %+merican 2etroleum nstitute& issues various standards, which are generally applied.

+ll measurements and tests have their tolerances, usually rather widespread and with correspondingly

great

economic consequencies. t is good practice to take all readings twice, repeat important tests twice etc?

Fith ships engaged in special trades it might be useful to be able to carry out the more common tests on

board and to train personnel correspondingly. his refers in particular to the testing of tank walls for

cleanliness. Many delays can be avoided if the ship:s officers can satisfy themselves that the tanks are

properly cleaned before entering port, using the same methods as the surveyor coming on board does.

?.01 Sampling o #argo$argo samples are taken for the purpose of checking whether the cargo satisfies a given specification or

not. Samples are also taken to establish if contamination has occurred during the voyage, during loadingor unloading or prior to loading.

+fter examination of the tanks, mudboxes, piping etc %as far as possible& for cleanliness it is usual to

load sensitive

chemicals into the ship:s tanks to a level of approximately ", 7 m and then take samples from the tanks,

presuming

that any previous residues in the piping are by then dissolved into the new cargo %::soak test5&. Similarly

samples are taken from an initial discharge into container tanks or similar located on the shore before

commencing unloading at full rate to the shore storage tanks.


31/128

fa 5soak test5 upon loading is turned down by the surveyor or the shipper and loading stopped, the

chief officer should then request sealed and identified samples of the cargo lot in question, from the

ship:s tanks as well as from the shore tanks. By these means the shipowner may be able to protect his

interests in case of any dispute.

Sometimes drip3samples are taken from the loading manifold during loading. his method is simple, but

not always fully representative. he pumping rate may vary during the transfer, whilst the sampling rate

is more or less constant. (urthermore it is difficult to guarantee the proper identity of a sample takenover a long period of time. his is not meant to discourage the ship)s officers from taking a drip3sample

during loading, but only to mention the weak points of the method. n fact, drip3sample during loading

may be the only way to establish whether a cargo was contaminated during the pumping on board or

ashore.

Before unloading cargo samples are normally taken from the ship:s tanks.

he cargo samples should be sealed and marked on board, particularly if no independent surveyor is

present. he ship should keep one sample for future reference in case of any disputes arising. he

samples should be stored in a dark and cool room especially put aside for this purpose. he room should

have steel bulkheads and be open to the weather deck.

Samples of products which deteriorate or change with, time %e g styrene, vegetable oils& have a limited

purposeful storage time on board.Fith e g phosphoric acid the samples may remain representative as

regards chemical composition, but may not be so as regards contents of sediments, =owever, normally

the samples are stored one year, which is the normal respite for making any claim.

Sampling at deep levels is carried out with containers which are lowered upside down or have valves orother means of filling themselves up at the deeper level. Sampling at various different levels is

necessary for products which have a tendency to stratify, viz phosphoric acid which may contain a higher

percentage of solids near the tank bottom than at top level.


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?.02 Cargo temperature etermination

he temperature difference between the top and bottom of a tank may be considerable. his applies

particularly to

shore tanks, where the ship)s officers are sometimes requested to attend when readings are being taken.

+SM

standard *"9#3;# %+2 4#!#& rules that temperature readings are to be taken at three levels when the

tank depth

exceeds !, # m. 'rdinary thermometers should be kept immersed at least # minutes at each level. he

most common type of thermometer is shown in fig #".

+s regards skin3contact dangerous products such as phenol, acrylonitrile etc one should, if possible,

avoid handling contaminated thermometers. Readings are much better taken by means of thermometerspocketed in the discharge manifold.

-lycerine or other suitable contact medium should be filled in the pocket in order to give a good thermal

contact.

Simple, portable, remote reading thermometers which can be lowered into the tank would be a welcome

development.

?.03 Spe#ii# gra>ity, ensity

Specific gravity expresses the weight of a unit volume of a matter compared with the weight of the samevolume of water, both at a defined %but sometimes different& temperature. Hxpressions such as S-

4"A4""$ are used in the petroleum industry. he first figure denotes the temperature of the product and

the latter the temperature of the water used as a comparison. Specific gravity includes the effect of air

displacement.


33/128

he specific gravity of water varies as follows/

! degr. $ *,""""

*# degr. $ ",GG94

4" degr. $ ",GG*7

f a specific gravity S- 4"A4""$ is to be converted to S- 4"A!"$ %!"$ is a common reference

temperature& multiply as follows/

S- 4"A! O S- 4"A4" x ",GG*7

*,""""

'ther examples/

S- *#A! O S- *#A4" x ", GG*7

*,""""

S- *#A*# O S- *#A4" x ",GG*7

",G"94

he tendency is now to use metric units in cargo calculations. he expression specific gravity is then

substituted by density and weight with mass. ensity is expressed in absolute figures, viz kgAm 7 at adefined temperature.

+ recalculation from specific weight to density involves a correction for the displacement in air by means

of a 5vacuum factor5/

ensity O Specific gravity

>acuum factor

he vacuum factor varies slightly with density %specific gravity&/

ensity *," ",G ",9 ",D

>acuum factor *,""*"9 *,""*44 *,""*7G *,""*;*

he difference between density and specific gravity is, as can be seen, small. +n error in applicationgives a discrepancy of abt *4 m P7 for a cargo of *" """ mP 7 %at S- ", G&.

ensity %and specific gravity& is measured by means of an areometer %hydrometer& or pycnometer.


34/128

principle. he determination is generally made at 4" " $. he use of pycnometers on board is not

practicable due to the need for a very sensitive weight scale.

Specific weightAdensity is part of all product specifications as a check on concentration, mixture etc. he

S-Adensity falls with the rising temperature. >olume correction factors are used for recalculation %per

degr. $ or degr. (& or tables %for petroleum products& available from, e.g +merican 2etroleum ndustry

%+2&.

+ warning/ t sometimes happens that cargo density and thus the quantity is determined at both the

loading end and the discharge end by means of areometers. 'bviously therefore there will be

discrepancies in the two quantity determinations simply due to the relatively poor accuracy in the

density readings. +s a result questions regarding cargo claims may arise. he answer is to use the 5asloaded density5 %whether completely correct or not& and correct it for the change in temperature at the

discharge end. his calculatedN density is then used in the quantity determination upon discharge.

hereby it can be established with good accuracy whether cargo has been lost or not.

here are also other specific gravity scales. $onversion can be carried out thus/

a& +23scale, commonly used for petroleum products/

+23gravity %at ;""(& O *!*,# 3 *7*,#

S- at ;"A;"n degr. (

b& Baume3scale, used for liquids heavier than water, e g sulphuric acid/

S- O *!#

%*!# Q degr.Baume&

here is also a Baume3scale for liquids lighter than water.

?.04 Colour etermition

Most products shipped in chemical tankers are pure and well defined. he colour is known and any

deviations

indicate the presence of contaminants.

Most chemicals, furthermore, are clear and translucent. + milky or turbid +ppearance indicates that

contaminants may be present.

+ sample is best studied in a test tube against a black or white background in good daylight.

Hmpirically a number of colour scales have been established. hey are each particularly suited for certain

kinds of products.

+ method called +2=+ %=azen& is

sea transport of liquid chemicals in bulk

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