schip en werf Onze zeehavens in de branding N, t O vernem ing van a rtik e le n e n z. zonder toestem m ing van de uitgevers is verboden

N,

t O vern em in g van a rtik e le n e n z . zo n d er to e s te m m in g van de u itg e v e rs is v e r­ boden. Jaarabonnem ent (bij vooruitbetaling) / 40.75. buiten Nederland / 67.25. losse nummers ƒ 2 95 van oude jaargangen / 3 75 (alle prijzen incl BTW)

schip en werf 1 4-da ag s tijd s c h rift, g e w ijd aan S c h e e p s b o u w . S c h e e p v a a rt en H ave nb ela ng en O R G A A N VA N :

NEDERLANDSE VERENIGING VAN TECHNICI OP SCHEEPVAARTGEBIED - CENTRALE BO ND VAN SCHEEPSBO UW MEESTERS IN N ED ERLAND - N ATIO N AAL INSTITUUT VOOR SC H EEP­ VAART EN SCH EEPSBO UW

-

NEDERLANDS

S C H EEPSBO U W KU N D IG

PROEFSTATION

REDACTIE: ir. J N. Jo u stra , p ro f. ir. J.H. K rie te m e ije r, p ro f. dr. tr W P A van L a m m e re n en J.G.F W arris - REDACTIE ADRES Postb 25123. Burg s'Jacob plein 10. R otterdam -2. Tel 36 54 17 UITG EVE R S

W VT

-

R O T T E R D A M -6

Tel 76 2 5 6 6 *. P ie te r d e H o o c h w e g 111 T e le x 2 1 4 0 3 . P o s tre k e n in g 5 8 4 5 8

Tweeënveertigste jaargang -

26 sept. 1975 -

no. 20

Onze zeehavens in de branding Op deze plaats behoeven wij nauwelijks te stellen, dat de recente actie van de onte­ vreden binnenschippers aan onze zeeha­ vens grote schade heeft berokkend. Hoe­ wel de ergste blokkade, namelijk die bij Maassluis, dankzij het kundig ingrijpen van de Rotterdamse autoriteiten snel tot het verleden behoorde, zullen de Scheepvaartvereniging Zuid en de Rotterdamse Kamer van Koophandel ongetwijfeld op goede gronden hebben verklaard, dat de actie de haven miljoenen heeft gekost, nog afgezien van het verlies aan reputatie. Stakingen en acties komen altijd op de meest ongelegen momenten - mede met het oog daarop worden zij doorgaans op die tijden georganiseerd maar in het geval van Rotterdam en Amsterdam kwam de stagnatie in het scheepvaart- en goederenverkeer inderdaad op een hoogst ongelukkig moment, omdat deze havens het juist nu zo zwaar hebben als gevolg van de algehele recessie. Enkele maanden geleden berichtten wij hoe mr. L. J. Pieters van de SVZ had verklaard, dat de daling in het goederen­ verkeer en de leegloop in de havenarbeid vrij hoge percentages hadden bereikt. Hoewel het nog onzeker was of de toe­ stand na de vakanties niet nog meer zou verslechteren, hield de SVZ op grond van toen gedane informaties onder reders en verladers, er rekening mee, dat in het be­ gin van 1976 sprake zou kunnen zijn van een lichte opleving. Die verwachting blijkt thans te optimistisch te zijn geweest. Op zijn vroegst zal eerst in het najaar van 1976 op enige opleving mogen worden gerekend, ondertussen neemt de daling in het goederenverkeer toe en moet gevreesd worden dat de werkgelegenheid in de ha­ ven ernstig in gevaar zal komen. De be­ drijven kunnen niet blijvend op basis van short-time de zaken gaande houden; vroeg of laat zal men zich aan de nieuwe situatie moeten ’aanpassen’. De daling van het S. & W. - 42e jaargang no. 20 - 1975

stukgoedverkeer in de Rotterdamse ha­ ven, die in de eerste vier maanden van dit jaar 11 procent bedroeg, heeft zich in de verdere loop van dit jaar voortgezet. De Kamer van Koophandel voor Rotterdam noemt de situatie, die op het ogenblik nog veel slechter ligt, verontrustend. De ka­ mer maakt zich ook zorgen over de sterke stijging van het aantal werklozen in de categorie minder geschikten. Bijna veertig procent van de mannelijke ingeschrevenen valt onder de categorie van de ’nauwe­ lijks plaatsbaren’. Onrustbarend moge de situatie in Rotter­ dam zijn, het is een last die de havens in West-Europa gezamenlijk torsen. Ook Antwerpen wordt hard getroffen. Het goederenverkeer over deze haven lag me­ dio september zo’n twintig procent onder dat van de vergelijkbare periode van 1974. Niettemin zijn de Antwerpenaren niet al te somber gestemd, omdat zij er toch altijd nog op rekenen dat zij 68 a 70 miljoen ton in 1975 kunnen halen, hetgeen bij elkaar genomen niet zó veel onder de 76 miljoen van 1974 ligt. Het afgelopen jaar was overigens een record voor Antwerpen, zoals het ook in vele andere havens en sectoren van de scheepvaart was, niet ten onrechte, omdat algemeen is aangeno­ men, dat in 1974 het summum is bereikt van de gunstige conjuncturele ontwikke­ ling, die zich rond 1970 ging inzetten. De tegenslag van de energiecrisis, de inflatie en de recessie in de wereldhandel lieten zich in de tweede helft van 1974 welis­ waar goed voelen, maar konden toen nog niet de zeer goede resultaten van het ge­ hele jaar teniet doen. Andere havens die een teruggang rapporteerden zijn Zeebrugge (-22 pet), Gent (-12 pet). Duinker­ ken (-10,6 pet), Le Havre (-21 pet), Marseille (-10 pet), Hamburg en Bremen (-13 pet). Niet alle percentages slaan op de­ zelfde perioden, sommige zijn van de eer­ ste zes maanden, andere van de eerste vijf

maanden. Het algemene verschijnsel is echter, dat de teruggang voortduurt en nog in vaart toeneemt. Niettemin getuigt het voorstel van burge­ meester en wethouders van Rotterdam om nu definitief een begin te maken met de bouw van een Containerterminal op de Maasvlakte van veel optimisme. Er moge dan sprake zijn van een recessie in de containeroverslag, Rotterdam is ervan overtuigd, dat deze van tijdelijke aard is ,zoals trouwens voor alle goederensecto­ ren die onder de huidige depressie lijden. Twee rapporten hebben B en W van Rot­ terdam tot basis gediend voor de beoorde­ ling over de benodigdheden aan containerfaciliteiten in de jaren die komen. Het eerste is van de hand van de talentvolle statisticus van de SVZ, drs. Biesheuvel, getiteld ’Containeriseerbare lading’, het tweede is opgesteld door de ESSOR, een ambtelijke werkgroep van Rijnmond en Rotterdam. In deze rapporten wordt gesteld, dat in 1980 vermoedelijk 1,2 miljoen containers

Inhoud van dit num m e r: Onze zeehavens in de branding Operational experiences with inert gas systems G.M.T. introduce new B series of low-speed engine The first tuna purse seiner 650 S.T. from the Gdansk shipyard Nieuwsberichten

387

in Rotterdam moeten worden overgesla­ gen. Dat is uiteraard aanzienlijk meer dan de huidige faciliteiten aan de ECT, Unitcentre, Bell Line, en elders zullen kunnen verwerken; vandaar dat in 1980 dan ook een groot stuk van het Maasvlakteterminal gereed moet zijn, althans zoveel, dat dit complex minstens 300.000 con­ tainers van het totaal voor zijn rekening kan nemen. Dit moet dan geschieden op een stuk grond van zestig hectaren, waar de aanlegkosten in eerste instantie op 55 miljoen gulden worden geraamd. Later, veel later, zal men moeten beschikken over een terrein van 400 hectaren, maar dan spreken wij al over de periode tot het jaar2000, waarvan overigens de schattin­ gen uiteenlopen. Sommigen houden het er op, dat het groeipercentage van het con­ tainerverkeer in de periode 1980-2000 3 zal zijn, maar anderen gaan er van uit dat er jaarlijks wel eens van een groei van 7 procent sprake zal zijn. De investering, die daarom moet worden gedaan is dus duidelijk geënt op een be­ hoefte waarover ieder het eens is; zij is

trouwens veel geringer in omvang dan de 300 (misschien wel 400) miljoen die nodig geweest zouden zijn, wanneer het oor­ spronkelijke Rijnpoort-plan tot ontwikke­ ling was gebracht. In het laatste stadium echter, voordat Rijnpoort definitief van de tafel werd geveegd, waren de SVZ, de gemeentelijke havendienst en de Kamer van Koophandel de mening toegedaan, dat de Rijnpoort-grond ’gereserveerd' moest blijven voor latere behoeften. Dat betekende uiteraard, dat toen al de oor­ spronkelijk voor Rijnpoort voorziene functie van containerhaven naar elders was verwezen; immers als Rijnpoort een containerhaven had moeten worden, dan was het noodzakelijk geweest, dat er on­ middellijk tot de bouw was overgegaan, zoals nu het geval is met de Maasvlakte. Anders zou Rotterdam in 1980 niet klaar zijn geweest om, waar dan ook, de eerste extra 300.000 containers op te vangen. Er is over die Rijnpoort ontzettend veel te doen geweest en nu nog betuigen velen hun spijt over de onherroepelijkheid waarmee het plan is afgewezen. Wij krij­

gen echter de indruk, dat men zich in Rot­ terdam wonderwel bij de situatie heeft neergelegd. De bezwaren tegen de containeroverslag op de Maasvlakte worden minder; wat is er in feite eigenlijk op tegen om containers daar te behandelen? Ook ten aanzien van de tweede functie die Rijnpoort was toegedacht zijn voldoende bevredigende alternatieven. De Stoom­ vaart Maatschappij Zeeland, bijvoor­ beeld, is bepaald niet ongelukkig over het feit, dat de veerboten in Hoek van Holland blijven, vooral niet wanneer straks daar over nieuwe moderne faciliteiten kan worden beschikt. Zeker niet ontevreden zijn de tuindersbedrijven in het Westland, die nu niet langer beducht behoeven te zijn voor een aanslag op hun grond en boven­ dien volop de gelegenheid krijgen om hun tomaten en groenten te blijven exporteren, niet alleen over Hoek van Holland, maar ook over Scheveningen (een haven die men in de hitte over de Rijnpoort-strijd nog wel eens over het hoofd zag). De J.

BIG LIFT VERVOERT REUZENKOLOM VAN 603 TON

Het Dordtse in zwaar transport gespeciali­ seerde bedrijf Big Lift B.V. gaat in op­ dracht van Fluor-Los Angelcs (USA) een kolom vanuit het Belgische Tisselt via Rotterdam naar Baytown/Texas (USA) vervoeren. Het betreft hier een omvang­ rijk land-/zeetransport van een kolom van 61,23 meter lang en een diameter van 11,69 meter. Het gewicht van deze kolom bedraagt 603 ton en is bestemd voor een raffinaderij in Baytown. Big Lift B.V. heeft deze opdracht ontvan­ gen, doordat zij is gespecialiseerd in ex­ treem zwaar transport en in staat is zware stukken van fabriek tot plaats van be­ stemming te vervoeren. Voor dit unieke transport maakt het Dordtse bedrijf gebruik van gekoppelde platformwagens met totaal 320 wielen, een ponton van 50 meter lengte en 13 meter breed en haar zware lading-/ro-roschip m.s. Lady Sophie. Het schip is voor dit transport speciaal voorzien van twee stabiliteitstanks, die aan de zijkant van het schip zijn bevestigd. Vanuit de fabriekshal van Griinges Graver S.A., die de kolom heeft vervaardigd, te Tisselt (België) werd de kolom op de plat­ formwagens met behulp van twee zware trekkers naar de waterkant langs het Ka­ naal van Willebroek gereden. Het totale treingewicht van trekkers, platformwa­ gens en kolom was ruim 850 ton. Via speciale rijkleppen werden de wagens op 388

de ponton gereden. Het tweede gedeelte vond plaats via de waterwegen naar Rot­ terdam. Met behulp van twee drijvende bokken

werd de 603-ton wegende kolom op het dek van het motorschip Lady Sophie ge­ plaatst, waarna het schip naar Amerika is vertrokken.

OPERATIONAL EXPERIENCES WITH INTER GAS SYSTEMS’ By J.E . R iley, B. Sc.,

C.

Eng., M l. M a r.E., T e ch n ica l M a n a g e r A irfilco M arine In sta lla tion s Ltd.*

Presentation on March 14, 1975 Centennial Year/Meeting of the State University of New York Maritime College Fort Schuyler

1. SUMMARY Inert Gas Systems are used to supply gas of sufficiently low oxygen content to prevent the formation of flammable atmos­ pheres in the cargo spaces of vessels carrying hazardous cargoes. The Inter-Governmental Maritime Consultative Organisation (IMCO) recommends that Inert Gas Systems are fitted for the protection of cargo in crude oil Tankers of 100 000 tons dead­ weight and over and for Combination Carriers of 50 000 tons deadweight and over. Inert Gas Systems are now being fitted by many shipowners on all types of vessels, crude oil tankers, combination carriers, product and chemical tankers, irrespective of size, both for New Buildings and existing vessels. A fire or explosion can only occur if the three following situations are together at one time:1. Flammable material 2. Source of ignition 3. Correct oxygen content Flammable materials will always be present aboard the vessel because of the types of cargoes being carried. A source of ignition is an ever-present hazard because of the possibility of human error. Possible sources of ignition are:(i) (ii) (iii) (iv) (v)

Smoking Hotwork Metal to metal contact Spontaneous combustion Static Electricity

The only positive way to effectively minimise the risk and possi­ bility of fire or explosion is to ensure that the oxygen content at all times is below that level which would enable ignition to occur.

Note: When special products, or chemicals are being carried, the ship's staff should be advised regarding the limits of flammability together with any other particular requirements concerning the carriage of the cargo. The diagram shows how the limits of flammability progressively narrow as the oxygen content reduces, and assumes conservative values in the envelope curve. The line A-B represents the 'critical dilution line’ when inert gas/hydrocarbon mixtures are suddenly diluted with air. If the hydrocarbon content for a given oxygen content lies above this line, as does point C, then the mixture would dilute with air through the flammable range (line C-B). If the mixture defined by the point C were purged with inert gas of high quality until the oxygen and hydrocarbon content reduced below the critical dilution line, as does point D, the subsequent dilution of this mixture with air cannot cause a flammable condi­ tion to occur. The diagram is particularly useful when considering the effects of collision, ventilation with fresh air, and purging with inert gas. The value of the Inert Gas System following a collision, other than for purposes of confining the possible fire to the breached tank, depends on whether the concentrations of the hydrocarbons and oxygen lie above or below the critical dilution line A-B. It also depends on the size of the breach and whether extensive mixing occurs with the outside air. In the loaded condition, when the hydrocarbon content is usually high, the atmosphere is likely to pass through the flammable range during dilution, so a period must exist when there is risk of explosion. When the tanks are empty, however, the ability to reduce the hydrocarbon gases in the tanks by purging with inert gas makes it possible to prevent fire or explosion in the event of collision. The purpose of this paper is to detail some of the operational experiences with Inert Gas Systems and to describe some of the modifications which have been incorporated to improve the re­ liability and life of the systems.

The vapours from volatile petroleum and chemical cargoes are mainly mixtures of the individual constituents. The concentration and the proportion of each component varies according to the 2. INERT GAS SYTEM type of cargo and other factors, incl uding the effects of shipboard Inciting systems fall into three main categories: operations. a. Use of boiler flue gases - which are low in oxygen content As inert gas is added to such mixtures, the flammable range b. Combustion gases produced from a specially designed oil becomes progressively narrower, as seen from the attached dia­ fired generator. gram ’Limits of Flammability of Hydro-carbon Nitrogen/Oxy­ c. Pure Nitrogen or Carbon Dioxide - either generated or sup­ gen mixtures. plied form bottles. Each gas component contributes to the flammability of a mixture with air in proportion to its concentration. a. Inert Gas System (Flue Gas) see Fig I The inert gas is supplied from the oil fired boiler exhaust eases. For crude oil and refined products carriers the usual limits of The oxygen content of the exhaust gases depends on the correct flammability, including a margin of safety, are quoted as 1,3% for the Lower Explosive Limit (LEL) and 11,5% for the Upper Explosive Limit (UEL). * Vertegenwoordigd door 'A. de Jong T.H .' B .V ., Rotterdam S. & W. - 42e jaargang no. 20 - 1975

389

combustion control and should be maintained by the operators below 5% at all timed. Alarms in the inert gas control panel give an indication of an oxygen content of 5% and then a second alarm level of 8%. Te inert gas offtake pipes from the boiler uptakes are fitted with isolating valves so that the source of inert gas can be selected depending on which boiler is in operation. The exhaust gases then pass into the base of a scrubber, where the exhaust gas is cooled and cleaned and also where the majority of acidic gases are absorbed. The inert gas is then drawn into the suction of the inert gas fan. Two identical 100% capacity inert gas fans are fitted so that in the event of one fan being stripped down for maintenance purposes, the system is always available for use at maximum capacity. Isolation valves are fitted at the inlet and outlet from the fans, which are sequence interlocked to open only when the inert gas fan has run up to full speed. The fan rotating assemblies have a very high rotational inertia and take approximately 60 seconds to run up to full speed. The isolating valves are left closed during this period to minimise the starting current by avoiding the additional load which would be caused by gas flowing through the fan during the start up. The inert gas then passes to the main isolation and recirculation valve. These valves are arranged to modulate so that there is a constant gas flow through the scrubbers and fans during the entire cargo discharge period, even though the rate of discharge is continuously varying. The function of these valves is described later in the text. The inert gas from the main isolation valve then passes to the

A IR FILC O IN E R T G ENERATO R

390

GAS

Deck Seal situated at the after end of the main deck, through a non-return valve and into the cargo tank distribution system. b. Inert Gas System (Oil Fired Package Generator) See Fig. II Fuel oil is burned under carefully controlled conditions to pro­ duce a gas having a low oxygen content. The burner unit, combustion chamber and scrubber, together with oil fuel equipment, fan and control panel, are mounted as an integral unit to facilitate installation. The control, alarm and shutdown facilities are similar to those for a Flue Gas System and conform to the necessary Classification Society requirements. Inert Gas Generators are normally supplied when the volume of exhaust gas from the ships boilers is insufficient to provide a volume of inert gas 25% in excess of the cumulative pumping capacity, or may be supplied to ’top up’ the pressure throughout the inert gas system during the voyage of a motor ship when the boilers are shut down. c. Inert Gas System (Storage Type) Nitrogen or Carbon Dioxide are normally only used for small capacity systems where the capital expense would be less than supplying an Inert Gas Generator. The major disadvantages of the 'storage' system are that the gas can only be used once, and that refilling facilities may not be available on a world-wide basis.

S. & W. - 42e jaargang no. 20 - 1975

NO

Fig. I Diagrammatic Arrangement of Inert Gas System - Flue Gas

DO n o t s u a

KEY

TANK TO BE POSITIO NED T O GIVE M IN IM U M HEAD OF 2 m AT PUMP SUCTION

VENT (AUXILIARY STACK)

FD

F L A M E DETECTOR

PC S

PRESSURE C O N TR O LLE R S TRAINER

PS

PRESSURE SWITCH

FS

FLOW SWITCH

LS

L E V E L SWITCH PRESSURE GAUGE

(pT)

PRESSURE

INDICATOR

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M OTOR STARTER

FO B

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rx rXj

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A

S O LE N O ID VALVE

PRESSURE R E G U LA TIN G VALVE

— [ X — ^-S T A N D B Y SEA WATER SUPPLY m3/h

N O TE VENT PIPE OUTLET TO BE TAKEN ABOVE HIGH WATER LE V EL IN GAS GENERATOR

1G G

:I' ouz

F

BASE

ACTUATED

IN E R T GAS SYSTEM

m^/h

SEA WATER PUMP

ORDER N ° HULL N° SHIPYARD

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DAT I

BERKSHIRE

f NGl * n Q

MG

FLOW DIAGRAM OIL FIRED G E N E R A TO R . CAPACITY PT Oa H C "* 0

Fig. II Flow Diagram - Inert Gas Generator

D r 'o il»

A I R FI L C D

12 -9 -7 4

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INERT GAS m3/h

1500/STD

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■IV

3. BOILER UPTAKE VALVES (See Fig. Ill) The boiler uptake valves are usually ’swing through’ butterfly valves of the wafer type. The valves are designed to operate at temperatures up to 450 °C and therefore have a specific clearance between the valve disc and body to avoid mechanical seizure at the elevated operating temperature. This clearance allows a certain amount of gas leakage to occur under service condition even though the valves are shut. For example, where the gap between the valve blade and the seat is 0,015 inch for a valve size of 24", the estimated leakage rates would be: For a differential pressure across the valve of 6" w.g. - leakage 1.6 cubic feet per second (160 m3/hr). For a differential pressure of 3" w.g. - leakage would be 1.12 cubic feet per second (112 m3/hr). When the boilers are operating, the exhaust gases, which contain quantities of sulphur trioxide and sulphur dioxide, diffuse and leak into the hot gas ducting and thence into the scrubber. These gases are readily absorbed by the wet surfaces within the scrubber and because of the possible concentration can cause accelerated corrosion of the internal components. Under normal operating conditions there is a continuous flow of sea water through the scrubber which limits the concentration of any acids. This corrosion during periods when the inert gas system is shut down is minimized by the fitting of air seal valves. 4 AIR SEAL VALVES On the boiler uptake side of each boiler uptake gas isolation valve, an air seal valve is fitted which connects to the discharge side of the boiler forced draft fans. The operation of the air seal valve is controlled by the same pneumatic signal which controls the boiler uptake valves. When the uptake valve is opened the air seal valve is closed, and when the uptake valve is closed the air seal valve automatically opens. This ensures that whenever the boiler forced draft fan is operating, a positive supply of fresh air flows to the hot gas side of the boiler uptake valve. This positive supply of fresh air prevents solids depositing close to the boiler uptake valve, which could cause sticking of the valve disc and incorrect opening of the boiler uptake valve. The supply of fresh air also prevents the gaseous diffusion of the exhaust gases which contain sulphur dioxide and sulphur trioxide into the hot gas ducting and into the base of the scrubber and enables internal inspection of the gas scrubber to be carried out whithout any discomfort to personnel. The hot gas from the boiler uptake passes into the base of the scrubber through a venturi, which is continuously immersed beneath the operating water level. The provision of air sealing, together with the water seal at the venturi, prevents the acidic gases condensing on the wet surface within the gas scrubber when the main scrubber sea water pump is not on and which could otherwise form concentrated acids and rapid corrosion of the internal metallic components. 5. SOOT BLOWER INTERLOCK The operation of the boiler off-take valves is interlocked with the operation of the soot blowers. An isolation valve is fitted in the steam supplyline between the boiler steam drum isolation valve and the soot blower control valve, which is pneumatically operated by the same pneumatic signal which opens and closes the boiler uptake valves. The air signal which opens the boiler uptake valve closes the soot blower steam isolation valve and the air signal which closes the boiler uptake valve opens the soot blower steam isolation valve, so that the soot blower can only be operated to clean the boiler genera­ ting banks when the inert gas system is not in use. A pressure switch is fitted between the steam drum isolation valve and the soot blower steam isolation valve to prevent the inert gas system being operated when the soot blowers are in operation. S. & W. - 42e jaargang no. 20 - 1975

Fig. Ill Operation of Boiler Uptake, Air, Sootblower Steam Isolation Valves

If the soot blower steam isolation valve on the steam drum was opened whilst the inert gas system is in operation, the pressure switch would energise the relay to close the boiler uptake valve on the boiler, an alarm would then sound and the system would go to full ’re-cycle’ until the steam pressure in the soot blower supply line was released. The operation of both systems at the same time would undoubt­ edly cause an excessive amount of solid particles to be carried by the exhaust gases into the scrubber, and thence throughout the system. The main objection, however, to the use of the soot blowers when the inert gas system is operating, is the practice of the Operating Engineers to increase the air/fuel ratio during the soot blowing operation to increase the gas velocity through the boiler, thereby increasing the oxygen content of the exhaust gases. This increase in oxygen content is not acceptable. The increase in Air/Fuel ratio increases the oxygen content of the exhaust gases which could then no longer be used as ’inert’. 6. HOT GAS DUCTING AND EXPANSION BELLOWS The boiler exhaust gases pass to the inert gas scrubber through the hot gas ducting and expansion bellows. The effects of acid condensate corrosion are the subject of much detailed investigation. Acid condensate corrosion can occur on any surface where the temperature is at or below 160 °C and therefore must occur at some point between the boiler offtakes and the scrubber inlet. The hot gas ducting should be kept as short as possible, compati­ ble with the positioning of the inert gas equipment within the machinery spates and long horizontal runs should be avoided. After prolonged operation of the plant, solids carried over in the

393

exhaust gases will deposit along the hot gas piping and these deposits will gradually build up. The resulting layer is extremely absorbent, and the acidic ash deposits, in contact with the steel piping, form an extremely active corrosion cell. The build up of these deposits also decreases the cross sectional area of the pipe and so increases the pressure losses on the suction side of the inert gas system. In the long term this reduction in cross sectional area will lead to a reduction in the overall perfor­ mance and capacity of the inert gas system. Wherever such horizontal lengths of hot gas ducting cannot by avoided it is imperative that cleaning access arrangements are provided and that regular checks are made on the condition of the pipe, especially after emergency operation of the boilers under abnormal combustion conditions. Wherever possible, expansion bellows should be mounted verti­ cally and should have inner sleeves. Premature failure of expan­ sion bellows has occurred because of the deposition of solids and condensate in the lower part of the corrugations of expansion bellows which have been mounted horizontally. 7. INERT GAS SCRUBBER The design and construction of the inert gas scrubber are of fundamental importance for the operation and protection of the entire inert gas system. The three important functions of the scrubber are: a. The cooling of the flue gases. b. The removal of solid particles extrained in the flue gases. c. The absorption of the acidic components of the exhaust gas. a. Cooling The flue gas scrubber is generally designed for processing ex­ haust gases having a maximum temperature of 450 °C, utilising sea water as the coolant having an asumed maximum temperature of 35 °C. Under these conditions, the gas temperature at the outlet from the scrubber will be within 2°C of the sea water temperature at inlet i.e. 37°C maximum. b. Removal of Solid Particles The collection efficiency, for removal of the solid content of the exhaust gas, is a function of the pressure drop across the scrub­ ber. This pressure drop is generally designed to be approximately 24" H :0, for removal removal of 99% of all particles greater than I micron in size, together with a substantial removal of sub micron particles. c. Absorption of Acid Gases The flue gas scrubber is designed to remove 95% of sulphur dioxide in the boiler exhaust gases, assuming a 3% sulphur fuel, when using sea water having an assumed temperature of 35 °C maximum. The removal efficiency increases with decreasing sea temperature to approximately 99% at 8°C. There are several different types of scrubber used for inert gas systems: Packed Tower Bubble Cap Tower Spray Tower Sieve Plate Tower Airfdco have standardized on the use of the sieve plate type of scrubber incorporating a venturi agglomerator. This type of scrubber has the following advantages: a. High efficiency for cooling, cleaning and gas absorption be­ cause of greater contact between gas and liquid. b. Reduction in overall height. c. Good access for inspection and maintenance of all compo­ nents. d. No risk of blockage or channeling of gases. See Fig. IV which is a cross section through a venturi gas scrubber with impingement baffle trays. The hot gases from the boiler uptakes pass into a venturi section fabricated of Incoloy 825, where the gas velocity is increased to approximately 200 feet per second. 394

Fig. IV Inert Gas Scrubber - Tray Type

Water is sprayed into the gas stream at a point up stream of the venturi. The high relative velocity between the accelerating water drop­ lets and the solid particles in the gas stream leads to very high particle collection efficiencies. The majority of the larger and heavier particles are then dischar­ ged from the base of the scrubber with the effluent water. The flue gas, which has now been cooled to approximately 75-80 °C passes upwards from the base of the scrubber, where irrigation sprays cool and completely saturate the flue gas. The saturation of the gas ensures that the physical conditions within the scrubber are accurately known and permits precise determina­ tion of the cross sectional areas for the flow of gas and liquid to achieve optimum scrubber performance as the exhaust gases pass up through successive stages of baffle trays. The action of the baffle tray is shown in Fig. V. The turbulent mixing of the flue gas through the impingement type baffle trays provides very efficient cooling of the gas, cleaning and removal of the lighter solid particles from the gas stream and also absorp­ tion of the acidic constituents. The particulate removal efficiency of scrubbers has been the cause of much detailed discussion and it is important to em­ phasize the govering criteria. A high total pressure drop across the scrubber will significantly decrease the available fan head for distributing the inert gas throughout the distribution system and the over pressure in the ullage spaces during cargo discharge. The scrubber designed performance should, therefore, be discus­ sed in detail with the Ship Owner and Shipyard to establish the maximum acceptabele pressure drop compatible with the overall system design. The acceptance of a higher pressure drop will in turn probably involve the selection of inert gas fans having a greater 'total head’ requiring an increase in absorbed horsepower and conse­ quent increased demand on the ships electrical system. At each plate stage within the scrubber there will be an equili­ brium condition for the absorption of the acidic gases by the sea demister which is normally fitted across the full section of the

FLUSHING SPRAY

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Fig. VII Inert Gas System - Alkali Scrubber

scrubber. The depth of the polypropylene mesh mattress is sized relative to the scrubber diameter to prevent any carry over of water particles into the cold gas ducting and fans which could cause corrosion and erosion of the fan casing and impeller and would be deposited to cause corosion generally within the sys­ tem. Providing the design velocities are correct through the demister, this type of ’droplet separator’ has been completely successful 1. After long periods of operation, however, salt encrustation can occur throughout the mesh and for this reason back flushing sprays are invariably fitted on the top of the scrubber to wash off the solid deposits. The back flushing sprays should only be used when the system is shut down, otherwise ’carry over’ will occur. After prolonged periods of steaming of the boilers with incom­ plete combustion conditions, there is a tendency for tarry vapours to condense within the inert gas system. The possible condensa­ tion of these tarry vapours should be considered at the design stage of the scrubber so that the scrubber efficiency is not signifi­ cantly affected, i.e. detailed design of sieve plate, choice of packing type etc. These tarry deposits can cause channelling of the gas flow and a reduction in performance of the scrubber with regard to cooling, cleaning and acidic gas absorption. Similar problems could also be caused where the scrubber sea water supply pump or emergency supply source, has been posi­ tioned aft of the tank washing outlet. This has happened, and the oil deposited throughout the particular type of scrubber being used, caused such a back pressure within the inert gas system that the system was inoperative. Adequate facilities must, therefore, be provided for removal of the internal components for cleaning. The upper manhole door of the scrubber should always be sized water which will depend on the vapour pressure of the gases and so that the individual sections of mattress demister can be remo­ on the sea water temperature at that particular stage. The progres­ ved for more thorough cleaning if necessary with solvents. sive absorption through the scrubber, which is dependent on the equilibrium conditions at each contact stage is shown typically in 8. ALKALI SCRUBBER (See Fig VII) On Product and Chemical carriers special precautions are taken to Fig. VI. After passing through the uppermost plate stage, the cooled and ensure that the inert gas has a minimum amount of contamicleaned flue gas then passes up through a polypropylene mesh nents.The inert gas passes from the gas scrubber to the base of an S. & W. - 42e jaargang no. 20 - 1975

395

alkali scrubber, which is designed to remove the remaining traces of sulphur dioxide and oxides of nitrogen, which are the by­ products of combustion within the boilers and which have not been completely absorbed within the gas scrubber. A. solution of sodium carbonate (Na COi), to which a small quantity of sodium sulphite (Na SOi) has been added, is circula­ ted in a closed loop across the lower two stages of the alkali scrubber. The base of the alkali scrubber acts as a reservoir and connects directly to the suction side of the alkali circulation pump. The alkali is delivered from the pump and passes across the upper baffle tray, down the downcomer, across the lower stage baffle tray, down the lower downcomer into the base of the scrubber. The upper stage of the alkali scrubber is of the bubble cap type. Sea Water, supplied from the scrubber sea water pump supply line, passes continuously over the bubble cap trays for final water washing of the inert gases to prevent any trace carry-over of alkali into the inert gas system. A demister of the polypropylene mesh mattress type is fitted in the upper section of the alkali scrubber to prevent carry-over of sea water into the inert gas system. The alkali scrubber is fabricated of mild steel, rubberlined,with a 3 mm thickness of ebonite. The baffle or sieve trays, forming the lower two absorption stages of the alkali scrubber, are fabricated from Incoloy 825. The upper bubble cap type tray is fabricated from polypropylene. The chemical reactions involved during the absorption of the sulphur dioxide and oxides of nitrogen are: (a) Na CCh + SO = Na SO.i + CO Sodium Carbonate -I- Sulphur Dioxide = Sodium Sulphate + Carbon Dioxide (b) Na2C03 + NO = NaNOs + NaNO: + CO Sodium Carbonate + Nitrogen Dioxide = Sodium Nitrate + Sodium Nitrite + Carbon Dioxide (c) Na:SO.i + 2NO = Nu (NO)2 SCb Sodium Sulphate + Nitric Oxide = Sodium Nitroso Sulphate The quantity of alkali being circulated contains sufficient rea­ gents for the absorption of the gases during one complete cargo discharge of the vessel. The alkali make-up tank, located adjacent to the alkali circuit pump, connects to the suction of the pump and contains one complete make-up charge, based on a maximum of 0.3% sulphur dioxide in the flue gases. For effective operation of the alkali scrubber, the re-agent in the absorption unit must be alkaline at all times. The alkalinity is continually monitored by the pH probe in the suction piping to the alkali circuit pump, which transmits a signal to the pH indica­ tor/controller in the main alarm panel. An alarm sounds in the panel when the pH falls below 7.0. The solution should then be dumped via the drain at the base of the scrubber and the contents of the alkali make-up tank run in to the scrubber base. A fresh supply of alkali make-up should then be immediately prepared and continuously available for use. Recent tests on a ’Product and Chemical’ carrier, having both a Gas Scrubber and an Alkali Scrubber, gave the following results expressed in parts per million. 2

2

2

2

2

2

2

2

2

2

9. INERT GAS FANS The majority of inert gas fan units are now supplied with electric motor drive except, where gas freeing duties on a large system involve absorbed horsepowers in excess of 350/450 hp where the prime mover normally selected is a steam turbine. The most common configuration is to have 2 off 100% electric driven fans. This arrangement incorporates complete duplication and therefore greater reliability. When one fan is unserviceable because of inspection or servicing, the inert gas system is still available at 100% capacity. The provision of 2 identical fans also reduces the total spare requirements and ensures interchange-ability of all parts in an emergency. Inert gas fan impellers are now invariably constructed of nickel aluminium bronze. This material is giving excellent results with minimal evidence of corrosion or erosion, and is preferred be­ cause despite the gradual deterioration within the acidic envi­ ronment, it can be regularly inspected to anticipate replacement and is not likely to exhibit sudden catastrophic failure. Several alternative materials are available but have yet to be proven after prolonged periods of operation within the inert gas system. It should be stated, however, that the reliability of the fan units is directly dependent on the efficiency operation of the scrubber. Earlier failures of fan units were primarily due to two main causes. (a) Corrosion/erosion of components forming rotating assembly. (b) Damage caused by imbalance due to solids depositing on rotating assembly. Efficient operation of the scrubber should minimize corro­ sion/erosion on components within the inert gas system and should minimize the passage of solids into the system which could deposit on the fan impeller. After building up to a certain depth these deposits become dislodged, thereby throwing the rotating assembly out of balance.

The service experience of many operators with many different systems has led us to standardize on inert gas fan design, such that the rotating assembly is mounted between pedestal bearings driven by the prime mover via a flexible coupling. The fan casings are split to facilitate removal of the rotating assembly without the dismantling of any ducting. The fan casing is generally protected with Epoxy, having a thickness of approximately 250 microns. Service experience shows that the Epoxy coating is adequate for the protection of the mild steel fan casing. Correct scrubber design will obviate the possibility of passing over of solid particles and water entrainment which would cause corrosion and erosion within the fan casing, particularly at the peak of evase. During periods of emergency operation, it is possible that particle and water carry-over could occur. It is imperative that a continuous drain be fitted at the lowest point of the fan casing, to prevent any build up of water level within the fan casing, thereby causing localised accelerated corrosion of the impeller. After the Inert Gas System has been operating under abnormal conditions, a complete inspection of all items should be carried together with a check on their correct functioning. A recent failure of an aluminium impeller used for gas freeing Location Sulphur Dioxide Nitrogen Dioxide was due to the drain connection in the bottom of the fan casing not SO: Nitric Oxide having been connected up. After the completion of 'gas freeing’, NO: + NO the cover for the louvered intake to the fan suction ducting had not Before Gas Scrubber 1600 250 been correctly closed and sea water passed into the fan casing and After Gas Scrubber 15-20 90-100 accelerated corrosion occurred of the lower segment of the fan After Alkali Scrubber Less than 2 30 impeller. This was immediately evident on starting up of the fan. A drain connection is provided at the lowest point of the fan The secondary purpose of the Alkali Scrubber for the removal of casing, which should be piped to a ’U' seal sized to prevent any oxides of nitrogen is becoming increasingly relevant as Health passing of the inert gas through the drain pipe line. Authorities are passing legislation to protect personnel against The fan drain can, if carefully positioned, be led into the effluent the potential hazard of these gases. pipe line from the scrubber, and should have no isolation valve, 396

thereby ensuring the possibility of continuous drainage of any effluent passing into the fan casing. 10. M A IN ISO L A T IO N A N D R E C IR C U L A T IO N V A L ­ VES

(Refer Fig. VIII) The main isolation and recirculation valves are of fundamental importance for the protection and satisfactory operation of the system, both when inerting and gas-freeing. The main isolation valve is positioned as close as possible to the final bulkhead through which the inert gas passes before entering the inert gas cargo tank distribution system. The valve closes immediately in the event of any of the following alarms/controls, to prevent any possibility of hydrocarbon gases passing back into the machinery spaces: 1. Deck Seal water ’low level’ or Tow flow’. 2 High water level in Gas Scrubber 3. Fan failure 4. Failure in water supply to Gas Scrubber 5. Closure of boiler uptake valve during inerting 6. High temperature after Gas Scrubber The recirculation valve is controlled to ensure a reasonably constant gas flow through the scrubbers and fans at all times when the system is being used for inerting. Constant gas velocity through the scrubbers ensures optimum gas scrubbing efficiency and also ensures a continuous flow of gas through the fans to protect against overheating. During inerting solenoid valve SV3 is energised and solenoid valves SV1 and SV2 remain de-energised. On start up the pressure in the inert gas main is approximately atmospheric and the signal output from the pressure controller is 3 psi. When the fan has reached normal operating speed and the fan isolation valves open, the pressure in het inert gas main will increase, so causing the signal pressure from the pressure control­ ler to increase to 15 psi. The output signal passes through solenoid valves SV2 to SV3 and SV1 to the positioner of the main isolation valve which is direct acting, i.e. increasing signal pressure increases the opening of the valve to permit gas flow to the system. The valve positioner is adjusted for the valve to open progressi­ vely for signal air pressures increasing from 3-9 psi. The output signal also passes through solenoid valve SV 2 to the positioner of the recirculation valve. The valve positioner is adjusted for the valve to be closed for signal air pressures between 3-9 psi and to progressively open between 9-15 psi. On ’start up’ there is a time lag betwee the opening of the fan isolation valves and the energising of the solenoid valve SV3 after the deck seal has drained. During this time the 15 psi signal from the pressure controller will open the recirculation valve and so protect the fan from overhea­ ting. After the deck seal has drained and SV3 has been energised, the main isolation valve will open and inert gas will flow to the cargo tanks. The pressure in the gas main will then fall and the signal pressure from the pressure controller will decrease to close the recircula­ tion valve and modulate the main isolation valve. (Initially limi­ ting the gas flow through the scrubber). During gas freeing Solenoid Valves SV 1 and SV2 are energised, and Solenoid Valve SV3 remains de-energised. Supply air pressure of 20 psi connects through SV1 to the main isolation valve positioner. The main isolation valve therefore remains FULLY OPEN. The signal line to the recirculation valve positioner is vented to atmosphere through SV2 and SV3. The recirculation valve therefore remains FULLY CLOSED. During GAS FREEING operation of the system, there must be a S. & W - 42e jaargang no. 20 - 1975

Fig. VHI Inert Gas System - Operation of Main Isolation and Recirculation Valves

continuous flow of air at all times to avoid over-heating of the fans. During INERTING, the pressure controller signal output con­ nects to a pneumatic indicator on the main control panel. The indicator shows the amount of opening of the recirculation valve for all positions between fully open and fully closed. 11. DECK SEAL The function of the deck seal is to safeguard against the possibi­ lity of hazardous gases passing from the cargo tanks back into the machinery spaces. The fundamental importance of the deck seal to prevent the return flow of hydro-carbons merits special consideration in the selec­ tion of materials to avoid corrosion. We have standardised on mild steel construction 5 mm thick, internally lined with 3 mm thick flexible ebonite. It is adviseable here to add a word of caution. The use of rubber lined vessels is comparatively new to some areas of the Marine Industry. It is essential that any contractors installing this type of equipment are made fully aware of the limitations that no hot work should be carried out directly on to a rubber lined vessel. Local heat, as cajused by welding, causes differential expansion between the steel and rubber, which causes a breakdown of the bond, blistering and subsequent failure. A non-return valve is positioned forward of the deck seal and the primary function of this valve is to prevent the flowing back of liquid along the inert gas main. The valve also acts to hold back the pressure surge of the gas whilst the wet seal is established. A typical Deck Seal as fitted aboard a ’crude-oil carrier’ is shown in figure IX. The level is maintained in the base by a weir. The lower end of the gas inlet pipe is immersed below the water by approximately 4 inches. If a back pressure builds up within the cargo tanks and inert gas main, the water level in the base of the deck seal is depressed and the water level in the gas inlet pipe rises. The vertical height of the gas inlet pipe is sized te ensure that the 397

liquid Pressure/Vacuum Breaker will ’blow’ to protect the tank structure before any possibility can occur of the hazardous gases passing up through the deck seal. The deck seal should be supplied with water at all times. A flow alarm is incorporated to warn the ship’s staff of inade­ quate flow of sealing water. A ’high’ level alarm and ’low’ level alarm are also fitted. The ’high’ level alarm is to give warning of the possibility of water build up and consequent carry over into the inert gas system. The ’low’ level alarm gives warning of the possibility of the base of the gas inlet pipe becoming exposed as the water level falls. Test cocks are positioned before and after the deck seal to enable the pressure drop to be measured during operation. As with the scrubber demister, the deck seal demister mattress can become salt encrusted over a prolonged period and cause an increase in pressure drop. The sections should then be removed (for cleaning) through the access manhole. The test cock before the deck seal should also be used daily for checking the gas quality between the deck seal and the main isolation valve in the machinery spaces. Any indication of the presence of hydro-carbons should be im­ mediately investigated. This might be due to an internal fault in the deck seal or due to a failure of the deck seal seawater supply. Inert Gas Systems are now being fitted on vessels of all sizes. The recent interest in fitting such systems on ’Product Carriers’ and ’Chemical Carriers’ has led to our development of a ’dry operating’ cyclonic deck seal. See Figure X .The seal is cylindrical, having two integral compartments one above the other, fabricated from mild steel lined with ebonite. The operation of this deck seal is as follows: Normal operation When the inert gas system is not in use, both compartments are full of water up to the normal operating level, as indicated by the float in the upper ’reservoir’ compartment, and as indicated by the upper float in the lower compartment. If either float is not in the correct operating position, a pneumatic signal initiates the appropriate alarm to the operator. A pressure switch is fitted to the sea water supply line to the seal, which in turn gives alarm if there is a failure of positive supply pressure to the deck seal. Operation of inert gas system Before the system can be operated the reservoir water level must be at the correct level and a positive sea water supply available to the seal. This interlock ensures that at least one automatic ’shut down’ is always provided. When the inert gas fan has run up to operational speed, a se­ quence interlocked relay transmits a pneumatic signal to open the deck seal drain valve. After the lower compartment has emptied, as acknowledged by the lower of the two float valves in the lower compartment, another pneumatic signal opens the main isolation valve and inert gas can pass into the inert gas main. Shut down of the system When any of the following conditions occur a. Loss of reservoir water level b. Inert Gas Fan Failure c. Boiler Uptake Valves close d. Scrubber Outlet High Temperature e. Fan Outlet High Temperature f. Scrubber Sea Water Low Flow: the Main Isolation Valve automatically closes, the Deck Seal Drain Valve closes and the Deck Seal Filling valve opens. This immediate and fully automatic shut down sequence protects against any possibility of hazardous gases flowing into the ma­ chinery spaces. 19S

EXTERNAL D U C T IN G S E L F SUPPORTING IN E R T GAS C A P A C IT Y rrflh r

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D IM ENSIO NS IN M ILL IM E T R E S

Fig. IX Wet Type Deck Seal

This type of ’Dry Operating’ Cyclonic Deck Seal has the follow­ ing advantages. a. There are no ’hidden’ components which could corrode and so permit undetected leakage of hazardous gases to occur. b. There is no possibility of water entrainment in the Inert gases flowing to the tanks. (Dew-point control is therefore possible if required for the carriage of special products) c. Low pressure drop, less than 1" water, during full flow opera­ tion. d. Rapid sealing action, approximately 30 seconds to fill com­ pletely. 12. PRESSURE/VACUUM BREAKER The Pressure/Vacuum Breaker is intended to protect the structure of the ship against the effects of both under pressure and over pressure within the inert gas system and cargo spaces. The Pressure/Vacuum Breaker, see Fig XI, is normally fabrica­ ted of mild steel internally coated with an oil resistent epoxy paint. The annular dimensions are sized so as to avoid excessive back pressure whether the Pressure/Vacuum Breaker is relieving ei­ ther a gas or a liquid. As a general rule to date, no attempt has been made to arrange indication for the system operator when the pressure/vacuum breaker has operated to safe-guard the system. In view of the obvious need for such indication, Airfilco are now arranging, for two float chambers to be fitted to the Pressure/Vacuum Breakers so that level switches can give pneumatic indication and alarm on either high or low pressure within the deck main as indicated by a reduction or increase in the operating level of the oil within the oil filled Pressure/Vacuum Breaker. 13. CARGO TANK DISTRIBUTION SYSTEM The sizing of the Inert Gas Main and offtake branches to the individual tanks will depend on the gas flow rates throughout the system. Generally the line velocities during Inerting are between 25 and 30 metres per second.

FIG X P.S.

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MATERIALS APPROVED BY

: 5mm

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: Lloyds Register of Shipping & R.I.Na

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Gas Inlet

Gas Out

A

p. 000

550

550

800

5000

1500

1000

10,000

'*00

400

1000

5000

1500

1000

15,000

450

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1800

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20,000

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1800

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25,000

600

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INERT G„S CAPACITY Mi/IIr

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Fig. X Dry Type Deck Seal S. & W - 42e jaargang no. 20 - 1975

399

The Inert Gas Fans are required by Classification and I.M.C.O. to be sized to provide 25% reserve capacity in excess of the total cumulative rated capacity of the cargo pumps. The pressure drops through the system should be calculated and compared with the ’total head’ availability of the Inert Gas Fans so as to ensure an acceptable over pressure in the ullage spaces during cargo discharge at maximum rate. The ’capacity’ rating of the Inert Gas System must be very carefully considered. The cargo pump performance curves relate the cargo pump vo­ lumetric rates of flow to specific suction and discharges heads. Some curves exhibit less flatness than others, which can lead to operational problems. If the pumps are operating, say, from the after tanks which are full, against a very low back pressure to the shore facility, the actual cargo pump discharge rate can sometimes be considerably more than the ’design’ rate. Under these circumstances the increase in the rate of cargo discharge has been known to exceed the reserve capacity of the Inert Gas System. The only solution then remaining is to slow down the cargo pump to ensure satisfactory over pressure within the Inert Gas System, thereby preventing ingress of atmospheric air to the cargo spaces. The Inert Gas distribution piping is generally constructed of seamless mild steel, internally coated with epoxy. All welded connection and flange welds should be well radiused and ground smooth to avoid undulations. The surfaces internally should be shot blasted to a minimum ofSA V and coated with a minimum of two coats to give a final dry coating thickness of approximately 300 microns of epoxy. For Product and Chemical Carriers the coating should be care­ fully selected to be compatible with the cargoes to be carried. Glass reinforced polyester piping has been used for the Inert Gas distribution system but there has been no feedback of operational experience with this type of piping to date. Fig. XI Pressure/Vacuum Breaker 14. FORWARD PURGE VALVE The isolation valve of the appropriate cargo tank should be At the forward end of the inert gas main we now recommend a opened, together with the forward purge valve, such that as the connection to a vent main which discharges via a forward mast­ cargo is loaded the inert gas is dispelled from the forward mast­ head riser. A pneumatically operated butterfly valve giving tight head riser. Towards the end of loading the isolation valve can be shut-off, and a non-return valve are fitted between the inert gas closed to ensure that a positive pressure of inert gas remains in the main and the vapour discharge main. The purge valve is pneuma­ tank. tically operated from the main control panel for the inert gas After completion of cargo loading the inert gas system can be systems, situated in the Engine control room. The forward purge used to top up all of the cargo tanks to the correct positive valve enables the gas throughout the inert gas systems to be pressure for the voyage. changed and purged as follows: I After opening up any of the components for inspection or 15. CARGO TANK PRESSURE MONITORING overhaul, which would admit atmospheric air having a high During the loaded or ballast passage of a Crude Oil Carrier, the oxygen content. inert gas system normally interconnects all of the cargo spaces II Enables the inert gas system to be commissioned and function except when purging, tank washing, gas freeing or inspections tested without opening any of the cargo tanks isolation valves. are being carried out. Cargo Tank Isolation valves, if fitted, are III Permits the cargo tank main distribution line to be purged to left open. eliminate any contamination caused by gaseous diffusion through The Inert Gas Deck Main pressure transmitter, which senses the leaking cargo tank isolation valves, when carrying several diffe­ main pressure forward of the Deck Seal and Non-Return Valve, rent grades of cargo as with a Product and/or Chemical carrier. indicates the pressure throughout the entire cargo system. The most remote points from the inert gas fans (No. 1, or No. 2 Aboard a Product Carrier which may be required to carry several Cargo Tanks) would have the lowest overpressure during cargo different vapour grades, the inert gas main separates forward of discharge because of pressure drops through the system. If the the Deck Seal and Non-Return valve into individual mains each purge valve was inadvertently left open, and a negative pressure having an Isolation Valve forward of the accommodation. developed in the forward tanks, it is possible that air would be Two inert gas mains are normally provided so that three vapour drawn into the tanks. grades may be carried. On occasions when a third vapour grade is To prevent this a non-return valve is fitted adjacent to the purge carried the cargo parcels would be loaded into centre tanks which valve. would be isolated from the inert gas main and allowed to breathe When the cargo tanks are being loaded, the inert gas must be normally during the voyage through P/V valves. The centre tanks dispelled from the system. The provision of the forward purge would then benefit from the protection of the surrounding inerted valve enables closed loading to occur, such the inert gases - tanks. which will not support human life - can be safely discharged at The remaining tanks, depending on the vapour grade of the cargo being carried, would remain permanently open to their respective mast-head height. During loading the inert gas system would not be in operation. inert gas mains. FLANGE TO BST A S A O R D IN

FROM G AS ___ MAIN

4 HOLES 28 D IA . _______ FOR 25 DIA. HOLDING DOWN BOLTS. ON F PC. DIA.

TO D E R T E R M IN E D IM E N S IO N X, C L IE N T MUST SPECIFY SPECIFIC G R A V IT Y & V IS C O S ITY OF S E A L IN G L IQ U ID T O 8E USED S T A N O A R D U N IT IS D ESIG N ED FOR LIG H T O IL W IT H SG 0.8 & VIS C O S ITY OF 66 SECONDS REDW O OD N o I

S T A N D A R D M A T E R IA L S OF C O N S T R U C T IO N ;

D ESIGN ED TO V E N T A T :

2

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5m m T H K M IL D STEEL W IT H O IL R ESISTAN T L IN IN G PRESSURE OF 0.21 kg/cm 2 V A C U U M OF 0.07 kg/cm 2

SIZE

A

B

C

D

d

E

F

250

3090

920

1175

500

250

1025

720

350

400

3240

1220

1475

800

400

1250

1020

500

450

3290

1320

1575

900

450

1325

1120

550

500

3340

1420

1675

1000

500

1400

1220

600

600

3440

1620

1875

1200

600

1550

1420

700

G

D IM EN SIO NS IN M IL L IM E T R E S

400

The inert gas main isolation valves forward of the Deck Seal and Non-Return Valve would be closed to avoid gaseous diffusion and cross contamination. In an emergency the Inert Gas System would be immediately available by opening the Inert Gas Main Isolation Valves as appropriate. On a ’Product’ and/or ’Chemical Carrier’, where up to twenty different parcels could be carried, special consideration must be given to the method of operation of the Inert Gas System. The monitoring of the individual cargo tank pressures, to avoid any possibility of ingress of atmospheric air, is essential. During the voyage, the cargo tanks must be isolated from the Inert Gas Main to avoid any contamination of the different parcels. The Inert Gas Deck Main Pressure Transmitter will indicate the pressure in the Inert Gas Main only. Each of the cargo tanks is fitted with an individual cargo tank pressure transmitter, which is normally situated under the for­ ward and after cat walk. A sensing connection is fitted between the cargo tank isolation valve and the tank entry and the sensing line connects at the other end to the control bellows of a pneuma­ tic pressure transmitter. The cargo tank pressure, -500 to +1500 mm H O, is re­ transmitted by the cargo tank pressure transmitter as a 3-15 pounds per square inch pneumatic signal to the control panel in the engine control room. The Pressure Transmitters are always positioned as close to the sensing point as possible to minimise the ’response lag’ of the instrument. Furthermore, the re-transmission of the air signal through the forward machinery bulkhead safeguards against the possibility of hazardous gases entering the machinery spaces. In the main control panel there is a pressure switch, a dial gauge and an indicator light to give alarm on low pressure for each of the cargo tanks, set at minus 250 mm H O. When any tank pressure falls below the set point (-250 mm H O) the alarm module flashes and an audible alarm sounds on the main SAAB Unit, indicating an alarm function in the inert gas system. The audible alarm will continue to sound until the fault is ack­ nowledged on the inert gas control panel alarm annunciator. When the fault is acknowledged the alarm ceases to sound and the light goes to a steady bright. The dial pressure gauges for the cargo tank pressures are fitted with a red indicator light to assist the operator to identify which tank has the low pressure. The alarm signal indicating low cargo tank pressure is also connected to initiate cargo shut-down, to prevent any damage to the ship’s structure. The pressure in any other tank falling below the set point will cause the alarm module to re-flash and re-initiate the double alarm until manually acknowledged, when the visual alarm will go steady bright and the double alarm will be cancelled.

CAUSTIC FILLING

*

2

2

2

Fig. XII Scrubber Effluent Neutralisation - Caustic Soda

produced from the exhaust gases from a boiler fired on bunker ’C’ fuel, having an assumed sulphur content of 3%, produces the equivalent of nearly one ton of sulphuric acid in the scrubber effluent. Fig. XIII Scrubber Effluent Neutralisation - Magnesium Hydroxide

16. NEUTRALISATION OF INERT GAS SCRUBBER EFFLUENT WATER (See Figs. XII and XIII) The topic of neutralising the acidic effluent water from the scrubber is frequently mentioned. We have now supplied two Inert Gas Systems where facilities were incorporated to fulfill this function at the special request of the Shipowner, both utilising caustic soda solution. We have been in contact with the appropriate authorities concer­ ning the problem of effluent neutralisation for guidance as to the chemical to be used which would have the lesser effect on marine life and also to determine whether it is preferable to accept the acidity of the effluent rather than neutralise the acidity, thereby increasing the total dissolved solids in the effluent water. The Authorities concerned with the protection of the environment have not yet formulated any specific requirements although they are concerned with all aspects of marine pollution. It is interesting to note that the use of 100 000 m3 of inert gas S. & W - 42e jaargang no. 20 - 1975

401

Neutralisation with caustic soda solution (See Fig. XU) Sodium hydroxide solution is injected into the salt water supply to the scrubber by means of a chemical pump and control valve. The amount of opening of the control valve is governed by the pH value monitored by the pH probe in the scrubber base. During the discharge of 100 000 m3 of cargo, the inert gas fans would supply approx. 125 000 m3 of flue gas. The neutralisation of the scrubber effluent during the discharge period would con­ sume 2 100 kgs of a 47% solution (the strongest commercial grade available) at a cost of approx. £ 50. Neutralisation using magnesium hvdroxide pellets (See Fig. XIII) In this alternative arrangement, the acidic effluent from the scrubber flows upwards through a bed of magnesium hydroxide which neutralises the acids to form soluble magnesium salts. No control on the flow is required because the magnesium hydroxide pellets will only dissolve in the presence of the acid in the effluent. A pH probe is positioned in the overboard discharge line after the magnesium hydroxide bed to indicate when the magne­ sium hydroxide approaches depletion. During the discharge pe­ riod using 125 000 nv1 of inert gas, approx. 650 kgs of magne­ sium hydroxide would be used at a cost of approx. £ 40. The magnesium hydroxide bed can be by-passed when neutralisa­ tion is not required. SUMMARY OF ADVANTAGES AND DISADVANTAGES Caustic Soda System Advantages: 1. Direct injection into scrubber sea water supply assists in sulphur dioxide removal from exhaust gases. 2. Supply availability on global basis better probably than mag­ nesium hydroxide.

17. A L A R M S A N D C O N T R O L S

It is imperative that alarm and safety ’shut down' functions are regularly checked. During a recent service visit to one of our systems installed on a large crude carrier, the regularity of checking alarms was being discussed with the ship’s staff and it was apparent that no regular checks had been carried out since the ship had been delivered eighteen months previously and when this was pointed out the First Engineer indicated the remaining controls and instrumenta­ tion in the Engine Room Control Room and said ’Where is the time?’ We recommed that all alarms are checked each voyage. The establishing of routine procedures for checking alarm and control functions is of fundamental importance. Ideally a ’check off’ list should be drawn up to include all important items and the periodic interval when checks should be carried out. This should then be ’agreed’ with the operators so that the ship’s staff can have the opportunity to comment on the practicality of the proposed procedures. In view of the increasing demands on ever fewer operators, we now recommend routine service visits either annually or biannually to carry out a full inspection of instrumentation, control equipment and alarms by our specialist engineers. These visits can also be timed so that our representative can instruct any newly arrived members of the ship’s staff in the operation and maintenance of the system. Under the general heading of ’Alarms and Controls’, special reference should be made to the monitoring of the quality of the inert gas. Frequently the use of the oxygen analyser provided for the inert gas system is considered for the additional duty of sampling the boiler exhaust gases. Special consideration should be given to this ’control loop’, bearing in mind that the primary function of the equipment is to monitor the quality of the inert gas actually passing through the inert gas supply main on the dis­ charge side of the fan to the cargo spaces. The I.M .C.O. requi­ rements make a particular point that the instrumentation provided should give continuous indication and permanently record at all times, the oxigen content of the gas being supplied to the cargo spaces.

Disadvantages: 1. Hazardous - special precautions required for handling. 2. Must be in solution form. 3. Must be concentrated for economical storage and should be maintained above specific temperature to avoid crystallisa­ tion. 4. Sensitive control equipment required. 5. Closed storage required to avoid crystallisation caused by absorption of carbon dioxide from atmosphere. 6. More expensive than magnesium hydroxide. C O N C L U S IO N S A N D A C K N O W L E D G M E N T S 7. Greater quantity required than magnesium hydroxide. I have attempted in the paper to highlight some of the areas which have given problems and, in some cases, possible solutions to Magnesium Hydroxide System obviate those problems. Advantages: 1 hope that the paper has shown that despite the increasingly 1. Non-hazardous demanding environment within which the essential components 2. No control valves necessary. of the Inert Gas System have te operate, the challenging target of 3. Easy storage - inert except in contact with acid. ever increased reliability and availability is being actively per4. Low maintenance - except replenishment of bed and occa­ sued. sional clearing of deposits. The viewpoints put forward in the paper are those of Airfilco, and 5. Cheaper than caustic soda. not of the B.P. Tanker Co. 6. Lower quantity required. I would like to acknowledge with thanks the assistance of my colleagues in the preparation of this paper and also those repre­ Disadvantages: sentatives of shipowners, shipbuilders, Classification Societies 1. Oil contaminated effluent would reduce exposed surface area and sea-going staff whose willingness to freely discuss and con­ of magnesium hydroxide granules and reduce performance. structively criticise the systems assist in the development of a 2. Possible build-up of insoluble salts. ’safer’ system.

402

G.M.T. Introduce new B series of low-speed engine

Announcing the introduction of a new B 900-type of low-speed engine rated at 3 350 bhp/cylinder at 125 rev/min, Grandi Motori Trieste - owned 50 : 50 by Fiat and the Italian Government - mark a further stage in development from their already well-established A-range of 2-stroke low-speed engines crosshead which will in due course be superseded by this improved class with higher specific outputs per cylinder (Fig. 1). At present the A 106 (1060 mm-bore 1900 mm piston stroke) of 4 000 bhp/cy­ linder at 106 rev/min and the A780 engine (780 mm-bore X 1600 mm stroke) of

2 200 bhp/cylinder are unaffected but the range of outputs of the much demanded A 900 is appreciably increased by the new B 900. The latest engine has the same bore (900 mm), piston stroke (1600 mm) and rotational speed of 125 rev/min of the A 900 but the output per cylinder is increa­ sed from 2,900 bhp/cylinder with a mean effective pressure of 10.30 kg/cm2 to 3 350 bhp/cylinder (11.85 kg/cm2 b.m .e.p.). This means that the power range of the A 900 series which has so far covered 17 400 to 29 000 bhp from 6-10 cylinders inclusive is stepped up to 20 100 to

Fig. I Comparative results o f the Grandi M otori Trieste A-class and the new B series engines

33 500 bhp from the B900. Eventually the entire A series will give way to the new B design and although no orders have yet been received it appears possible that the first B-class production engine will be a 10-cylinder 900 mm-bore engine of 33 500 bhp. Higher outputs for specific cylinder size mean, of course, reduced cost and weight per horsepower. As production at the rela­ tively new Trieste plant gathers momen­ tum substantially more low-speed engines will be delivered per year; in 1974 the G.M.T. output was 16 units totalling 107 cylinders and 341 000 bhp while licencees in Italy contributed a further three engines aggregating 34 000 bhp. Included in the G.M.T. production figures for 1974 were four ’super-large-bore’ A 1060 engines of 38 cylinders and 152 000 bhp aggregate output, and five of the previouslymentioned A 900 units which totalled 98 600 bhp. Principal characteristics of the B-series are given below with those of the A-class in parenthesis. (See next page) Dimensions are basically unchanged and, in general, the design of the B series cor­ responds to that of the A class; Cross-scavenging with two stages of air compression and cooling, the lst-stage ha­ ving exhaust-gas turbochargers supplying at constant pressure while the 2nd-stage is by engine-driven double acting scavenge pumps. Water-cooled pistons. There are differences, however, in respect of the engine structure, parts of the crankgear and combustion chamber, and the injection system. The B design has been evolved from intensive research on G .M .T.'s experimental two-cylinder A 1060 engine and features: 1. A stiffened, closely-ribbed bedplate consisting of cast steel transverse beams welded to two sheet-steel fore-and-aft gir­ ders. 2. A box-type frame to give greater overall rigidity and a lower production cost. 3. Improved crank mechanism with white-metallined steel thinwall top and bottom end bearings. 4. By raising the crosshead pin, impro­ ved lubrication of the crosshead has been obtained. 5. A more effectively cooled combus­ tion chamber. 6. A different combustion chamber pro­ file giving increased peripheral area. 7. An improved fuel injection system which injects more fuel per cycle in the shortest possible time. (Fig. 2) 8. New-type piston rings.

S. & W. - 42e jaargang no. 20 - 1975

403

Engine Type B 1060 B 900 B 780

Cyl. Dia. mm. 1060(1060) 1060 (1060) 1060 (1060)

Piston Stroke mm. 1900 ( 1900) 1600 (1600) 1600 (1600)

Although lever-driven scavenge air pumps are being retained for the 2nd-stage of pressure-charging, having proved ef­ 4600 (4000) fective and reliable, research is continuing 3350 (2900) at the G.M .T. experimental test centre 2500 (2200) into the possibility of supercharging in The eventual characteristics of the entire B two stages of expansion of the gas and series will be as follow: compression of air by turbochargers. Ex­ perience has shown that the thermal and B 1060 B 900 B 780 Stroke/bore ratio mechanical stressing in the combustion 1,79 1,77 2,05 Piston area, cm2 chambers of ’A’ engines is kept within 8 829 6 362 4 778 Swept volume, dm3 reasonable limits of reliability even at out­ 1 677 1 018 764 Max. continuous rating bhp/cyl puts of 4 600 hp/cyl. However, since the 4 600 3 350 2 500 Speed, rev/min medium-term objective is towards even 106 125 126 Bmep, kg/cm2 greater specific outputs, some alternative 11,64 11.84 11,68 Mean piston speed m/s solutions have been designed, manufactu­ 6,71 6,67 6,72 red and tested with a view to increasing the No. of cylinders 6 to 12 6 to 10 5 to 10 cooling and the mechanical strength of cylinder heads, jackets and pistons. Two types of cylinder head were produ­ one in cast steel, subdivided, ribbed, Fig. 2 Comparative fu el injection characteristics o f the A-arul B-class Grandi Motori Trieste ced: and with forced cooling and the other in low-speed engines. forged steel with cooling through machi­ EN G IN E TYPE A 1060 ned holes. Both were capable of guaran­ Kp/cm 2 teeing adequate factors of safety even at 106 RPM - 4 000 BHP/cyl 5 500 hp/cyl. 900The cylinder jacket is cooled more effecti­ vely by reducing the wall thickness but T.D.C. 800tests are in progress on the experimental engine on a jacket the top half of which is force-cooled via holes machined in the wall. G.M.T. state that reduction in temperatuof the piston and on the piston in way of the top piston rings improves the already proven anti-scuffing feature of the stepped taper-faced piston ring successfully adop­ ted by them some time ago in their own engines. The greater mechanical stress on the piston rings as a result of the increase in maxi­ mum combustion pressure necessitated a thorough examination of the behaviour of these important elements, both in the ex­ perimental engine and in engines in servi­ ce. This led to two possible solutions: sha­ ping of the piston ring butts with ’eagle’s EN G IN E TYPE B 1060 K p/cm 2 beak' connection so as to eliminate frac­ 106 RPM - 5 500 8 H P /cyl ture due to contact with the liner ports; or 900production of sectionalised continuousT.D.C. sealing ring, recently patented by G.M.T. 800Service experience accumulated has shown that the adoption of ’eagle’s beak’700type rings given 8 000 hours between maintenance periods of the pistions. 600BHP/cyl.

rev/min

M.E.P. kg/cm2 106 (106) 11.6 (10.1 125 (125) 11.9 (10.3 126 (126) 11.7 (10.3

t v j v H n d n iv L . v n r I iiv / j i k I ivC i w U l i d i 'Tl TLa ' vL .

500-

400-

FU E L V A L V E L IF T

300-

1.2

200-

S h '0.8 -

404

0.6 0.4

100-

“i

1

30

35

r~ 40

0.2

Top- and bottom-end bearings A bottom end bearing with partial lubrica­ tion grooves has been produced and tested and retains the present level of reliability; as it has smaller longitudinal dimensions, it has allowed strengthening of the crank­ shaft, a prerequisite for the higher specific outputs. For the crosshead bearings, the lubrication of which is one of the most difficult pro­ blems in 2-stroke engines, two solutions are now available which give dependable

operation up to the maximum outputs achieved in the experimental engine. Both methods involve raising the bearing pin so as to allow the formation of an adequate film of lubricating oil. In addition to ensu­ ring satisfactory cooling of the bearings it

gives the necessary hydrody namic lift du­ ring the compression phase of the oil film, which can be verified when the maximum load is acting on the pin. The first of these solutions raises the pin by springs which transmit a constant force

upwards to the crosshead pin. This was conceived and produced as long ago as 1962, and after having been thoroughly tested in service on a 900S engine, was recently tested on the experimental engine A 1060, 2 at the maximum outputs.

GVK voorkom t corrosieproblemen bij offshore boringen Een grote slijtvastheid is een ander belangrijk punt. omdat in het gat opnieuw geboord moet kunnen worden nadat de bekleding is aangebracht. Voorts mag het materiaal niet verbrijzelen door de druk van springladingen die gebruikt worden voor het kraken van de omringende laag om de olietoestroming in de putbodem te bevorderen. De buizen moeten een gladde en schone opening vormen voor het schieten. GVK voldoet aan al deze eisen. SEPMA hoorbuizen worden gemaakt volgens het wikkelprocédé met als uitgangsmaterialen Roving 891 van Owens-Corning Fiberglas Europe S.A. en een epoxyhars met een anhydride als verharder en een aromatische amine als versneller. Kenmerkend voor dit Rovingtype, dat speciaal ontworpen werd voor wikkelprocédé’s en continu-impregneertechnieken, zijn de uitstekende Grote sterkte De hoorbuizen zijn bekledingsbuizen die aangebracht worden in bevochtigingseigenscha'ppen, geringe catenary en goed behoud het pas geboorde boorgat. Zij worden vastgezet met cement ter van sterkte in bevochtigde toestand. verkrijging van een sterke en waterdichte geleiding voor de Voordelen van GVK opvoerkolom. Door de buitengewoon goede corrosiebestandheid biedt GVK in ELF stelde hoge eisen ten aanzien van de sterkte-eigenschappen. het boorbedrijf vele voordelen boven staal. Door de ongunstige De eenmaal geïnstalleerde buizen kunnen niet worden uitgewis­ klimatologische omstandigheden in het equatoriale gebied van de seld en iedere beschadiging maakt de put voor verdere exploitatie westkust van Afrika corroderen sommige metalen pijpen reeds onbruikbaar. De hoorbuizen moeten bestand zijn tegen de tijdens tijdens de opslag voordat zij in gebruik genomen worden, een het cementeren optredende in- en uitwendige drukken en tegen de probleem dat zich bij GVK niet voordoet. Ook de gebruiksduur van GVK bekledingen is langer dan die van normale werkdrukken. staal. De in 1971 bij wijze van experiment in het Emeraude-veld geïnstalleerde GVK onderdelen functioneren thans nog steeds zonder enige storing. Een ander voordeel is het geringe gewicht van glasvezelversterkte kunststoffen, waardoor de buizen gemakkelijker te hante­ ren en goedkoper te transporteren zijn. Het Franse olieconcern ELF ondervond ernstige corrosieproble­ men bij het begin van de offshore boorwerkzaamheden in het olieveld Emeraude buiten de westkust van Afrika. De in dit veld aanwezige ruwe olie is zwavelhoudend en bevat bovendien kooldioxyde, ten gevolge waarvan de hoorbuizen in minder dan een halfjaar tijd aangetast worden door corrosie. ELF wendde zich daarom tot de Société d’Exploitation des Pro­ cédés Plastrex-Manurhin (SEPMA), fabrikant van GVK pijplei­ dingen en tanks, met het verzoek een boorbuis van GVK te ontwikkelen die bestand zou zijn tegen bovengenoemde corro­ sieve invloeden.

SEPMA kon met succes gevolg geven aan de uitdaging van ELF, en heeft sindsdien vele duizenden meters GVK pijp geleverd voor soortgelijke toepassingen in het boorbedrijf. De SEPMA hoorbuizen zijn verkrijgbaar met een inwendige diameter van 50 tot 218 mm, in lengten van 6 m. De toelaatbare werkdruk varieert met de binnendiameter en kan tot 120 bars bedragen, met een overeenkomstige maximale inwendige druk van 600 bars en een uitwendige bezwijkdruk van 170 bars. De trekvastheid is zodanig dat GVK buizen geschikt zijn voor ge­ bruik tot diepten van 1500 m. Grote toekomst De heer Pierre Huber, technisch directeur bij SEPMA, voorziet een grote toekomst voor GVK apparatuur in de petroleumindus­ trie, zowel voor land- als zeeboringen, en wel in het bijzonder vanwege de corrosiebestandheid. Een 6 m lange SEPMA boorbuis wordt door het boorplatform langzaam neergelaten in een nieuw boorgat, ter verkrijging van een sterke, water­ dichte geleiding voor de opvoerkolom. Het gebruik van dit type bekledingsbuis van glasvezelversterkte kunst­ stof in plaats van staal neemt hand over hand toe. De buizen zijn vervaardigd van Roving 891 van Owens-Corning Fiberglas en een epoxyhars met een anhydride als verharder en een aromatische amine als versneller. S. & W. - 42e jaargang no. 20 - 1975

405

THE FIRST TUNA PURSE SEINER 650 S.T. FROM THE GDANSK SHIPYARD

The Albatun, the first of a series of tuna purse seiners, was delivered in August this year, by the Gdansk Shipyard to the Mexican Owner, the Sociedad Cooperativa de Produccion Pesquera ’Albacoreros y Atuneros del Estado de Baja California’. The vessel is designed as a tuna purse seiner for service in the fishing grounds of the Central Atlantic and Pacific in the tropical zone. Main Dimensions: Length, o.a. abt. 52,90 m, Length, b.p. 47,50 m., Breadth, mid. 11,30 m., Depth, to upper deck 7,55 m., Depth to lower deck 5,25 m ., Draught, mid. 5,20 m. The capacity of the tanks used to freeze tuna in brine and to store same in dry frozen condition is of abt. 740 m3. The capacity of the basic fuel oil tanks of abt. 270 m3 for diesel oil may be increased by a further 230 m3 if four fish tanks are used for the carriage of fuel oil. The fresh water store in tanks is of abt. 40 m3. The ship is powered by a diesel engine developing 2910 bhp/metric/ at 900 rpm. and driving a fixed propeller, through a reduc­ tion gear. The propulsion power installed allows a speed of 14,8 knots at the ship’s full load to be achieved. The fishing gear is adapted for a purse seine of up to 1200 m in length and of up to 110 m in depth. The purse seine is set by a skiff with a driving power of abt. 300 BHP/metric/, and by four motor speed boats. The ship is built to the Class: ’+ A 1 Fishing Service’of the American Bureau of Shipping. The stern ramp, inclined at abt 30 degrees, is adapted for the hoisting of the skiff. The aluminium superstructure comprising two tiers is connected to the steel deck by means of rivets with a special insert. Three375 kVA generating sets, 3-phase 460V. 60Hz., including diesel engines of the Caterpillar D353 type, four-stroke, develo­

ping abt. 430 bhp /metric/ at 1200 rpm. are installed in the ship. The electrical and radio navaids comprise gyro compasses; a vertical echo sounder for depths to abt. 200 m; a vertical echo sounder for depths to abt. 750 m; an automatic radio direction finder; two navigating radars and an Omega navagation receiver. The fish freezing reefer plant is adapted for operation at an air temperature of + 38 °C and water temperature of + 29°C Ammonia is used as refrigerant. The tanks are cooled by means of cooling coils, with three pressure values applied for the direct evaporation of the cooling medium. The vessel is designed to chill fish in sea water, to freeze fish in brine within a forced circulation system, and to store frozen fish in dry condition at abt. -12° C.

LLOYD’S REGISTER TO CERTIFY HOWARD DORIS CONCRETE PLATFORM BUILDING AT STROMSTAD, SWEDEN, FOR NORTH SEA FRIGG FIELD

At the request ofTotal Oil Marine Limited. Lloyd's Register is to certify a concrete gravity type intermediate manifold platform ordered from the Howard/Doris Partnership to be installed on the pipeline route from the Frigg Field to Scotland. The platform is being built by Skanska Cementgjuteriet at Stromstad in Sweden. Lloyd’s Register is carrying out design appraisal of the primary structure and shop inspection of steel reinforcement, steel sec­ tions and plate at steel mills in the UK and overseas. Inspections are also being carried out at the manufacturers' works of pre­ stressing tendons and pre-cast concrete elements. It is estimated that 7000 tons of reinforcing steel, 2600 tons of pre-stressing steel and 50 000 cubic metres of concrete will be required during construction. Lloyd's Register is also surveying the construction of the plat­ form foundation raft and the subsequent erection of the platform afloat in sheltered water at Stromstad in Sweden. Surveyors will witness the towout and emplacement of the structure on the Frigg Field pipeline route as a prelude to the issue of a final Certificate of Fitness. The Total Group platform is similar to the one being built at Andalsnes, Norway, and is essentially a hollow concrete cylinder 9 metres in diameter and 127 metres high through which the manifold riser pipes are led to the surface. Surrounding this central core and linked to it by internal concrete bracings is an outer cylinder 62 metres in diameter. Both central core and outer cylinder stand on a concrete raft 101 metres in diameter suppor­ ting walls 15 metres high. 406

The design of the structure incorporates the Jarlan perforated breakwater principle to reduce the effect of wave and current action. The outer concrete cylinder is perforated with 1.2 metres diameter holes for a distance of 11 metres above and 26 metres below the waterline. To reduce the scouring effects of the current at seabed level the raft foundation has an outer wall 15 metres high with perforations 1.29 metres in diameter. For the structural analysis of the platform the Lloyd’s Register LOCS computer system has been used. This system was develo­ ped for the analysis of concrete offshore platforms and is an essentia] tool in the difficult task of determining the distribution of forces and moments throughout the structure. In addition to the conditions expected in service, Lloyd’s Register will examine those which will be met during fabrication, launching of the foundation raft, completion afloat, towing, installation on loca­ tion as well as any exceptional environmental considerations. The base raft is being constructed in a graving dock at Stromstad which will be flooded on completion, allowing the raft to be towed into deeper sheltered water where the rest of the central core and outer cylinder will be added afloat by the use of conti­ nuous slip forming moulding and simultaneous pre-stressing. As the structure is built up it will gradually sink and be maintained in a suitable attitude for towage to the location in the North Sea. Following the tow the platform will be ballasted so that it comes to rest on its seabed location.

Nr

yj

NEDERLANDSE VERENIGING VAN TECHNICI OP SCHEEPVAARTGEBIED (Netherlands Society of Marine Technologists)

Voorstel voor lezingen seizoen 1975-1976 P ro du ctieb esturin g m et ko sten be w a ­ Nieuwjaarsreceptie k ing en eventuele com pute rtoe p assing 2 jan. 76 (vr) Rotterdam door de heer ir. A. Boesten (Ingenieurs­ 5 Jan. 76 (ma) Groningen door de heren P, C- D am en A. van der bureau Sandwijk B.V.) Haarlem Vlies van Orqanteatie Adviesbureau Ydo 22 apr '76 (do) Rotterdam BV. Problemen rond olie-verontreiniging23 apr. 76 (vr) Amsterdam 3 okt. '75 fyrf Amsterdam Aard, eigenschappen en toepassing 27 apr. 76 (di) Groningen in het Gev&ke-Groenpoihuäs van dispergeermiddeien boorde heer J. B. Af (FinaNederiahdB V.} M arine m ain shafting bearing d eve lo p ­ M oderne inzichten bij de opzet van 29 jan. 76 (do) Rotterdam* m ents scheepsw erven 30 jan 76 (vr) Amsterdam d o o r. .. van Glacier door ir. W. L. Bastian van Bureau Naval 3 febr. 76 (di) Groningen 13 met 7 6 (do) Rotterdam Consult Holland en medewerkers 14 met '76 (vr) Amsterdam 23 okt. '75 (do! Rotterdam* 24 okt. '75 (w) Amsterdam Geluidshinder aan boord van scheper»* 18 rrtei ’76 (di) Groningen 11 nov. '75 ;a } Groningen Dagbijeenkomst te Delft door medewer­ Reserve vo ordrach te n: kers van de Technisch Physische Dienst Hydrodynamische aspecten van Off­ TNO/TH O ptim aal m e te oro lo gisch routeren en 19 febr. 76 (do) Delft shore constru ctie s* navigeren door dr. ir. J. P. Hooft door dr. C. de Wit 13 nov. '75 (do) Delft Het sfepen en plaatsen van Offshore De Tekenkamer, een achtergebleven s e ctor in het com m unicatieproces

constructies ir

C. D. Donafh (Smit internationale) heer Th. van Duuren, registerac­ door 28 febr. (do) Rotterdam controller KNSM-Groep N.V.. 27 febr. 76 76 (vr) Amsterdam. 2 mrt 76 (
B e stu ursinfo rm a tie

door de countant. Amsterdam 20 nov. 21 nov. '75 (vr) Amsterdam 25 nov. ’75 (di) Groningen

T oepassing van een luch tva artg astu rb ine in de scheepvaart

door Ltz T 1e Kl. R. M. Lutje Schipholt 18 dec. '75 (do) Rotterdam

Seagoing tug and barge

door de heren ir. R. W. Bos, M. F. van Sluys, prof. ir. N. Dijkshoorn en drs. L. Blank 25 mrt. '76 (do) Rotterdam* 26 mrt. '76 (vi) Amsterdam 30 mrt. '76 (di) Groningen

V rije keuze

19 dec. '75 (vr) Amsterdam 23 dec. '75 (di) Groningen

BALLOTAGE De volgende heren zijn voor het gewoon L id­ m aatschap de Ballotage-Comrhissie gepas­ seerd: F. J. ADR1AANSE Afgest. Hogere Zeevaartschool voor Scheepswerktuigkundigen, Amsterdam, HTS-structuur Bakkumstraat 3, Amsterdam G. J. M. ANDRIESSEN Afgest. Hogere Zeevaartschool voor Scheepswerktuigkundigen, Amsterdam, HTS-structuur; Assistent-Chef Technische Dienst C.M .C. Melkunie B .V ., Rotterdam Amsterdamsestraatweg 89. Naarden J. BALLIJNS Jr. Afgest. Hogere Zeevaartschool voor Scheepswerktuigkundigen, Amsterdam, HTS-structuur; W erktuigkundige Esso Tankvaart M aat­ schappij Antaresstraat 12, Emmeloord S. & W. - 42e jaargang no. 20 - 1975

Algem ene Ledenvergadering

28 apri. '76 (wo) Hardinxveld

J. N. BOS Afgest. Hogere Zeevaartschool voor Scheepswerktuigkundigen, Amsterdam, HTS-structuur; Scheepswerktuigkundige Pastoor van Muijenweg 14, Heiloo A. Chr. VAN DER EIJK Afgest. Hogere Zeevaartschool voor Scheepswerktuigkundigen, Amsterdam, HTS-struetuur; Scheepwerktuigkundige bij Smit-Lloyd B .V ., Rotterdam Irenestraat 5, Monnickendam Chr. C. ZAAL Afgest. Hogere Zeevaartschool voor Scheepswerktuigkundigen, Amsterdam, HTS-structuur; Scheepswerktuigkundige bij de Neder­ landse Scheepvaart Unie, Rotterdam le van Swindenstraat 4 5 ', Amsterdam Allen voorgesteld door H. Brouwer A. E. VAN DODEWEERD Oud-Scheepswerktuigkundige (met diploma C l); Bedrijfsassistent Scheepsreparatiebedrijf Niehuis en van den Berg, Rotterdam Kwartellaan 17, Vlaardingen Voorgesteld door P. de Weerdt

N.B.

1) Lezingen gemerkt * samen Sectie Scheepstechniek KM.

met

18 en 19 april '76 Pasen 27 mei '76 Hemelvaartdag 6 en 7 juni '76 Pinksteren Naar behoefte kan van het programma worden afgeweken. Bovenstaand programma zal in 'Schip en W erf worden herhaald. W ij­ zigingen of aanvullingen kunnen hierin voorkomen.

Ing. D. KLEYN Afgest. HTS afd. Electrotechniek; Hoofd Elec­ tro Technische Dienst Hollandsche Aanne­ ming Mij., Rijswijk Beeklaan 104, Noordwijk-2460 Voorgesteld door M. Rietveld H. KRAAIJEVELD Directeur Deltawerf B.V. Joost van den Vondelstraat 1, Sliedrecht Voorgesteld door A. Meuzelaar ir. M. F. WINKLER, w .i., Ingenieur van Bureau Veritas, Rotterdam Lijsterbes 22, Krimpen a.d. IJssel Voorgesteld door L. Nobel B. VAN WOERDEN Directeur Rijnsleepdienst B. van Woerden CV. Dresdenlaan 20, Rotterdam Voorgesteld door H. van Liefland

407

NEDERLANDSE VERENIGING VAN TECHNICI OP SCHEEPVAARTGEBIED VERKIEZING HOOFDBESTUURSLEDEN Wegens het periodieke aftreden van de heren Prof. ir. J. H. Krietemeijer (herkiesbaar), J. G. F. Warris (niet herkiesbaar) en E. Botje (afdelingsvertegenwoordiger Groningen, herkiesbaar) is door het hoofdbestuur en de afdeling Groningen de volgende voordracht opgemaakt Prof. ir. J. H. Krietemeijer Ir. J. N. Joustra Voor de afdeling Groningen 1. E. Botje 2. H. Bitter Overeenkomstig art. 14 lid 4 van de statuten kunnen tenminste 10 leden eveneens kandidaten voordragen bij de Algemeen secretaris. Stembiljetten zullen t.z.t. aan alle leden worden toegezonden.

NIEUWSBERICHTEN Personalia

Hij volgt dan Ir. A. Kuijl op, die met ingang van dezelfde datum benoemd is tot directeur van de Caltex Raffinaderij te RaunheimDuitsland (50% Chevron, 50%> Texaco).

Benoemingen hij de Smit Internationale Groep Smit Internationale Havensleepdienst BV te Rotterdam (onderdeel van de Smit Internatio­ nale Groep) deelt mede dat per I oktober 1975 tot adjunct-directeur van de vennootschap is benoemd de heer W . M. van Amen. De heer Van Amen, die reeds 38 jaren in de havensleepvaart werkzaam is, vervult de func­ tie van Hoofd Exploitatie Binnenland van Smit Internationale Havenslcepdienst BV, terwijl hij tevens is belast met de leiding van de Slecpvaartccntrale van Zeeschepen te Rotterdam.

Punoccan benoemt General Manager voor haar tankopslagbedrijf in Rotterdam Panocean heeft mr. J. J. van Oostendorp (41) benoemd tot General Manager van Panocean Tank Storage L td.’s opslagactiviteiten in Rot­ terdam. De heer Van Oostendorp is per I sep­ tember 1975 in dienst getreden. De heer Van Oostendorp zal worden geassis­ teerd door de heerC . W. M eeuwessen, Operations M anager, en de heer P. C. Sigmond, Commercial M anager Netherlands, Panocean Tank Storage Limited.

Smit Tak Zeetransport BV, onderdeel van de Smit Internationale Groep (zee- en havcnsleepvaart, berging, zwaar transport te water en andere maritieme dienstverlening), deelt mede dat met ingang van 1 september 1975 tot directeur van deze onderneming is benoemd Kapt. D. Borohers (37). Kapt. Borchers heeft een jarenlange ervaring, zowel praktisch als comm ercieel, op het gebied van zwaar transport over zee. op welk gebied de Smit Internationale Groep haar activiteiten wil intensiveren. Het tot de Smit Internationale Groep behorende transportbedrijf BV Sleepdienst & Transport­ onderneming Gerrit J. Eerland LCM Zn. (di­ recteur de heer A. J. P. C. van Dijk) voert zwaar transport op de Europese binnenwateren uit. Smit Tak Zeetransport BV exploiteert 7 zee­ gaande pontons, waarvan er 3 speciale afzinkpontons zijn. Hiermede worden transporten van o.a. baggermaterieel en andere drijvende objecten uitgevoerd, waarvan de belading en lossing geschiedt door middel van op- en af­ drijven. De in exploitatie zijnde vloot van Smit Tak Zeetransport wordt binnenkort uitgebreid met de in aanbouw zijnde ponton7«/: 12 (afme­ tingen 113,7 x 31,7 x 8 meter). Ir. M. van der Lippe M et ingang van 1 oktober 1975 is Ir. M. van der Lippe, thans Direkteur Fabricage voor Chevron Oil Europe Inc. te Brussel, benoemd tot Direkteur van de door Chevron beheerde raffinaderij te Rotterdam -Pemis (68.4% Che­ vron. 31.6% Texaco). 408

P. J. F. van der Meer Mohr Bij Koninklijk Besluit van 23 augustus 1975 is met ingang van 1 september 1975 benoemd tot waterschout te Rotterdam en Amsterdam de heer P. J. F. van der Meer M ohr, Schout bij nacht b.d. I)rs. H. J. Viersen voorzitter Commissie Binnenscheepvaart Staatssecretaris Van Hulten van Verkeer en W aterstaat heeft drs. H. J. Viersen, oudwethouder van Rotterdam, bereid gevonden als voorzitter op te treden van de Commissie Bin­ nenscheepvaart. Tot instelling van deze commissie werd on­ langs besloten toen gebleken was dat de Tweede Kamer de evenredige vrachtverdeling wilde handhaven. De commissie zal regering en bedrijfsleven op korte termijn adviseren over maatregelen die de gang van zaken in de binnenscheepvaart kun­ nen verbeteren. Aan het werk in de commissie zullen vertegenwoordigers deelnemen van schippers, verladers, reders, expediteurs en vervoersbonden alsmede ambtenaren van Ver­ keer en W aterstaat, Economische Zaken, So­ ciale Zaken en Financiën. Het secretariaat wordt ondergebracht bij het directoraat-generaal van het Verkeer. De heer Viersen heeft eerder dit jaar het voor­ zitterschap bekleed van een werkgroep die staatssecretaris Van Hulten concrete voorstel­ len voorgelegd heeft voor verbetering van de positie van de zeescheepvaart. Het overleg over de bezetting van de overige zetels in de commissie binnenscheepvaart is nog gaande.

De commissie is 15 september 1975 voor het eerst bijeengekomen. Atlas Copco opent bijkantoor in Groningen In verband met groeiende vraag naar perslucht door toenemende industrialisatie in de noorde­ lijke provincies heeft Atlas Copco Nederland b.v., Zwijndrecht, een bijkantoor geopend in Groningen. Het is het derde filiaal van deze Zweedse persluchtspecialist in Nederland. De persluchtgebruiker kan in het nieuwe bij­ kantoor terecht voor de aanschaf van compres­ soren, pneumatische gereedschappen, verfspuitapparatuur, componenten en vele andere persluchtprodukten. Ook wanneer men wil hu­ ren heeft men er een uitgebreide keus uit persluchtapparatuur. Een goed geoutilleerde service werkplaats hoort eveneens tot de uitrusting van het bijkan­ toor. Deze is vooral afgestemd op spoedop­ drachten. Tenslotte kan men bij het bijkantoor ook terecht voor technische adviezen over persluchttech­ niek. Het filiaal is gevestigd aan de Rouaanstraat 14, Groningen, tel. 050-18 03 33. Stichting M ateriaalonderzoek in de Zee Offshore techniek en wetenschapsbeleid Onder deze titel zal de Stichting M ateriaalon­ derzoek in de Zee op 16 december 1975 haar jaarvergadering houden in de Aula van de Technische Hogeschool te Delft. In de ochtendzitting is de eerste spreker Z. E. de M inister van W etenschapsbeleid de heer Trip. over Beleidsvoornemens en Nieuwe Or­ ganisatiestructuren in het W etenschapsbeleid. In de middagzitting ligt het accent op de ont­ wikkeling van de offshore-techniek, belicht door vooraanstaande gebruikers. Inlichtingen bij de Stichting Materiaalonder­ zoek in de Zee, Rotterdamseweg 137, Delft, tel. 015-13 32 22 - toestel 4725. 4th International Congress on M arine Corrosion and Fouling Het 4th International Congress on Marine Corrosion and Fouling zal gehouden worden van 14-19 juni 1976 te Juan-les-Pins, Antibes, Frankrijk. Het secretariaat van dit congres is Centre de Recherches et d ’Etudes Oceanographiques 73-77 rue de Sèvres, 92100 Boulogne-surSeine, France.

sleep- en bergingswerk, zeetransporten en an­ Lips Third Propeller Symposium, 1976 Lips Propeller Works of Drunen, Holland, are dere vormen van maritieme dienstverlening. organizing their third Propeller Symposium, to De onderneming heeft zich onder de naam Smit be held on 20 and 21 May 1976. The objective International South East Asia (Pte) Ltd. geves­ of the Symposium is to provide a forum for tigd in het International Plaza Building te Sin­ everyone concerned with the problems of ma­ gapore. rine propulsion and to discuss present-day de­ Tot directeur is benoemd Kap. G. A. Niemann. velopments leading to the propulsion systems De maatschappij is opgericht om de activiteiten van de Smit Internationale Groep op het zeer of the future. The central theme of the Symposium is the link specialistische terrein van bergingswerk, het between theory , and practice in the Field of transporteren van zware ladingen over zee door marine propellers for high speed ships of every middel van pontons en het overslaan van aller­ size, offshore drilling and auxiliary platforms, lei zware objecten in het Verre Oosten te be­ vorderen. Bovendien kan het bedrijf diensten icebreakers and large vessels. The Symposium will be held in the Cocagne verlenen aan de oiieindustrie, zoals het plaat­ Hotel, Eindhoven. The programme includes a sen van boeien, het leggen en ophalen van de visit to Lips propeller production plant and to verankeringen van booreilanden, het uitvoeren an exhibition of vintage cars at Lips Autotron van duikwerkzaamheden, enz. Hoewel Smit Internationale sedert een aantal in Drunen. Further information may be obtained from mr. jaren een vaste basis heeft in Singapore, waar F. Bult, Lips Propeller W orks, Drunen, Hol­ doorlopend één of meer van haar zeesleepboten gestationeerd zijn, verwacht men door middel land. van de nieuwe maatschappij nog directer dan voorheen de scheepvaart, scheepswerven en de TEC H NISC HE H O G E S C H O O L D ELFT olie- en transportwereld in Zuid-Oost Azië te Geslaagd voor het doctoraalexamen elektro­ kunnen dienen, Smit International South East Asia (Pte) Ltd. technisch ingenieur F. H. M. Bergen, Voorburg heeft het bergingsmaterieel overgenomen dat S. J. M. Blom, Leiderdorp tot dusver werd gebruikt door Singapore Ocean Salvage, een plaatselijk bergingsbedrijf. J. A. Bolder, 's-Gravenhage K. L. Braber, ’s-Gravenhage Nieuwe behuizing Wilro Koeling B.V. A. F. C. Eldering. Oegstgeest Mei ingang van heden is het nieuwe adres van H. B. Groen, Delft (met lof) bovenstaande vennootschap, Voorhaven 101, C. J. den Hollander, Hoek v Holland Rotterdam-3007, telefoon: 010-76 94 99*. M. J. J. Koekkoek, Dordrecht A. J. A. Nicia, Rotterdam (met lof) Nieuwe behuizing Netherlands Offshore R. Pfaff, Amsterdam Company M. G. Reissenweber, H.I. Ambacht Met ingang van 1 september 1975 is het nieuwe E. W. Schieke, Delft adres van bovenstaande company, WaterleiT. J. M. Tensen, Edam dingstraat 4, Vlaardingen, tel. 010-35 80 17. H. C. Vogelaar, Rotterdam M. A. Vonk, Delft Nieuwe behuizing Geveke Motoren en L. J. W eeda, Rotterdam Grondverzet B.V. Geslaagd voor het doctoraalexamen scheeps­ Gezien de groei van de Divisie Motoren is het noodzakelijk gebleken een ruimere behuizing bouwkundig ingenieur te zoeken. mej. M. P. Bogaerts, Delft Met ingang van 1 oktober 1975 zullen de staf Netherlands Offshore Company en verkoopafdelingen van de Divisie Motoren Netherlands Offshore Company heeft op 25 bereikbaar zijn op de Kabel weg 25, Amster­ augustus 1975 met succes een zgn. jacket ge­ dam, Postbus 1225, telex: 12219, telefoon: plaatst op het Montrose olievelt in de Noord­ 020-80 28 02. zee. Het jacket is geplaatst op een waterdiepte van Doop "Smit London’ door Lady Mayoress van Londen 300 voet. In de komende weken zal Netherlands Off­ De bergings-zeesleepboot Smit London shore Company die als hoofdaannemer op­ (22.000 ipk) van Smit Internationale Zeesleeptreedt het platform vastheien, de deksecties en Bergingsbedrijf BV te Rotterdam zal op 8 aanbrengen en de boor- en produktie units in­ oktober 1975 in de ’Pool’ van Londen worden stalleren. gedoopt door de Lady Mayoress van de City of De installatie-procedure waarbij het tewaterla- London, Lady H. Fox. ten van het 6000 ton wegende jacket een van de De Smit Rotterdam - het zusterschip van de meest kritische onderdelen was, is door het Smit London - werd op 6 december 1974 door ingenieursbureau van Netherlands Offshore H.M. Koningin Juliana gedoopt en te water gelaten op de werf ’De M erwede’ te Company voorbereid. In voltooide toestand heeft de constructie een Hardinxveld-Giessendam. hoogte van 150 meter boven de zeebodem. Bij dezelfde werf werd op 25 april 1975 deSmit Netherlands Offshore Company is een doch­ London te water gelaten; de doop van dit schip termaatschappij van Bos Kalis W estminster volgt nu in Londen. Group N .V ., Hollandsche Beton Groep N. V ., In ’Schip en W erf zal t.z.t. een uitvoerige Stevin Groep N.V. en Koninklijke Adriaan beschrijving aan deze zeesleepboten worden Volker Groep B.V. gewijd. Smit Internationale versterkt positie in Zuid-Oost Azië Smit Internationale heeft in Singapore een be­ drijf opgericht, dat zich zal bezighouden met S. & W - 42e jaargang no. 20 - 1975

Kleurcode cilinders HoekLoos, leverancier en fabrikant van industriële-, medische- en laboratoriumgassen, heeft een kleurcodekaart voor gascilinders

uitgegeven. Op deze goed verzorgde en geplas­ tificeerde kaart staan de kleuren aangegeven, zoals die in Nederland door de Nederlandse gassenleveranciers voor de verschillende gas­ sen en gasmengsels worden aangehouden. In totaal worden in dit overzicht de kleurcoderingen aangegeven van 43 verschillende gassen en gasmengsels. Voorts bevat de kaart informatie inzake de ver­ schillende cilinderaansluitingen. alsmede een reeks van veiligheidsvoorschriften onder het motto 'gebruik cilinders veilig’. Overal waar men regelmatig met gascilinders te maken heeft, dit kan zijn in een werkplaats, op een scheepswerf, in een ziekenhuis, op een laboratorium etc. etc., behoort deze kaart aan­ wezig te zijn. De wandkaart wordt op verzoek gratis toege­ zonden en is evenals alle overige adviezen en technische informatie met betrekking tot gas­ sen en gasmengsels in het algemeen, verkrijg­ baar bij HoekLoos Amsterdam. Aanvragen: HoekLoos, Transformatorweg 40/Postbus 663, Amsterdam, tel. 020-82 28 51, toestel 328. Tewaterlatingen

Op 12 september 1975 vond bij de Nederlandsche Dok- en Scheepsbouw Maatschappij (lid van de Rijn-Schelde-Verolme Groep) te Am­ sterdam de tewaterlating plaats van de 225.000 ton d.w. turbinetanker Nepco Bahamas (bouwnummer 872), in aanbouw voor Nepco Bahamas Corporation, Monrovia, Liberia. De doopplechtigheid werd verricht door Mrs. Margaret Hunter.

Hoofdafmetingen: lengte over alles 330 m, lengte tussen de lood­ lijnen 314,12 m, breedte op de spanten 48,68 m, holte naarde mal 25,60 m, zomerdiepgang tot onderkant kiel 19,92 m. draagvermogen 229.935 metrische tonnen, capaciteit lading-tanks 282.341 m \ capaciteit schone ballasttanks 27.032 m3, voortstuwingsinstallatie 32.000 apk, proeftochtsnelheid 16.10 kn. Classificatie: Lloyd’s + 100 A l, oil tanker, pt. H.T. steel. Tankindeling: 6 middenlanks, waarvan No. 3 uitsluitend voor waterballast, 2 x 8 zijtanks, waarvan de ach­ terste aan weerszijden dienst doen als slobtanks. Constructie Geheel gelast, staal van hogere vastheid in dek en bodem. Accommodatie: Voor een bemanning van 40 in 1-persoonshutten. Een 2-persoons eigenaarshut en een 2-persoons loodshut. Gehele accommodatie voorzien van aircondi­ tioning. Machine installatie: 1 General Electric cross compound, doublé reduction geared steam turbine, max. duurvermogen 32.000 apk bij 80 om w ./m in., fabri­ kaat V .M .Y ./N .D .S.M . 1 Foster W heeler type hoofdketel, stoomproduktie 115 ton per uur maximaal bij een druk van 63 bar en een temperatuur van 513 °C., fabrikaat N .D .S.M . 1 Foster W heeler type hulpketel, stoomproduktie 30 ton per uur maximaal bij een druk van 62 bar, fabrikaat V .M .Y . 2 Verdampers met een capaciteit van 40 ton per 24 uur. 409

I Turbo alternator ! .400 kw., I diesel alternator 900 kw. en I nood diesel allcrnator 900 kw. I 4-bladigc nikkel aluminium bronzen schroef met bronzen muts, op schroefas bevestigd middels het spieloze SKF-systeem (opgeperst met oliedruk), schroefdiameter 9,40 m, ge­ wicht schroef 55.5 ton. Lading- en ballastpompen: 4 Stoomturbine gedreven verticale ééntraps centrifugaalpompen voor ladingbchandcling, capaciteit elk 4.000 m3 zeewater per uur. 1 Stoomturbine gedreven verticale centrifugaal ballastpomp. capaciteit 3.000 m ' zeewater per uur. 1 Verticale stoom duplex stripping pomp, ca­ paciteit 350 m 3 zeewater per uur. 2 Stripping eductors; capaciteit 500 m 3 zeewa­ ter per uur.1 Ballast eductor; capaciteit 250 nv’zeewatcr per uur. 1 Vacuum stripsysteem, geschikt voor gebruik met 4 ladingpompen. Rechte pijpstukken van lading-, ballast- en strippingsysteem van nodulair centrifugaal ge­ goten ijzer. Bochten, T-stukken, schotslukken etc. van staal. Lading- en ballastafsluiters - vlinderkleptype, van opperdek af bediend; afsluiters in ponip-

kamer bediend van pompcontrolekamer uit. Alle afsluiters hydraulisch bewogen met hydromotor direct op de afsluiter. Dekwerktuigen: De anker- en verhaallieren zijn stoomgedreven, trekkracht verhaallieren 25 ton. Op de bak 4 verhaallieren, elk met 1 trommel en 1 verhaalkop; 2 aan 2 gecombineerd met 1 ankerlier. Op het opperdek achter de bak en vóór het dekhuis 1 verhaal!ier met 2 trommels en 1 kop: op hel opperdek achter het dekhuis 2 verhaal­ lieren met 2 trommels en 2 koppen. Er zijn 2 stoomgedreven laad-/slangenbehandelingslieren, elk met trommel en kop. Trekkracht 8 ton. Alle anker- en verhaallieren en de laad-/slangen bchandelingslieren zijn produkten van het R .S .V .-bedrijf M achinefabriek IJmuiden te IJmuidcn. 2 Elektrisch gedreven dekkraantjes van 1,5 ton op het achterschip voor het laden en behande­ len van proviand en onderdelen voor de machi­ nekamer. 1 4-rams elektrisch hydraulische stuurmachine met 2 pompeenheden. Ankers en kettingen 2 Stokloz.e boegankers en I reserve anker, elk 18.800 kg., 742,5 m ankerketting, schalmdikte 107 mm; totaal gewicht ± 177.500 kg.

BOEKBESPREKINGEN

’Met de Spray de wereld rond’ door Joshua Slocum Uitgave: Unieboek bv, Bussum v t j i c t u i w W , k 'S ^ - i r Paperback afm. 14,5 x 21 X 1,9 cm ., 203 blz., geïllustreerd. Prijs ƒ 19,90 Van de uitgever werd de vijfde druk ontvangen van het boek van kapitein Slocum over zijn eenmansreis met de kotter 'Spray' rond de wereld. Op 27 juni 1898 keerde hij in Newport, U.S. A. terug na een reis van ruim drie jaren. Op eenvoudige en sobere wijze vertelt hij in dit boek van zijn avonturen op die lange reis. Het verhaal is niet altijd boeiend en bij een aantal gevallen zou men wat meer détailgegevens hebben verwacht. Zo vind ik het gedeelte over zijn ’dubbele’ tocht door Straat Magellan wat summier en men vermoedt dat er over de belevenissen tijdens de storm die de ‘Spray’ naar Kaap Hoorn voerde meer boeiends te vermelden zou zijn geweest. De voetnoot van de vertaler op blz. 108 is niet juist. Kapitein Slocum vergist zich niet als hij over de walvissen spreekt die uit hun neusgat(en) spuiten., (zie o.a. Mar. Encycl. dl. 7 blz. 159 waar over neusgaten, de blowholes. wordt gesproken; ook de Winkler Prins Ene. geeft dit aan). Afgezien van deze kritiek toch een aan te bevelen boekje, ook al vanwege de 16 fraaie tekeningen door Gerard Schaap die ditmaal zijn opgenomen. Prof. Ir. J. H. Krietemeijer Proceedings ’Gastech 74’ Van de Gastech Exhibitions Ltd., 2 Station Road Rickmansworth, Herts. WD3 1QP. England, ontvingen wij de 286 p. Proceedings van het 'Gastech LNG/LPG Technology Congress’ dat van 13-14 november 1974 in de RAI te Amsterdam werd gehouden. Het boek bevat de 19 voordrachten die tijdens het congres zijn gehouden alsmede de discussiebijdragen. Een vijftal van deze voordrachten is gewijd aan nationale projecten voor LNG trans­ portsystemen, terwijl de overige voordrachten een breed scala van de problemen rond het LNG transport behandelen. 410

Lloyd’s Register co-ordinates research into ship propulsion systems and vibration ana­ lysis Due to the increasing demand for design stage analysis of static and dynamic behaviour of main propulsion shafting systems Lloyd's Re­ gister is now co-ordinating research into this field. The Section responsible is headed by Mr. D. K. M artyn,C . Eng., under the direction of Mr. W. M cClimont, B .Sc., C. Eng., Head of the Research and Technical Advisory Services Department. The work undertaken is of a consultative nature and is not limited to vessels classed with Lloyd’s Register. As in the past, much work will be carried out for Design Consultants and overseas Governments. The scope of the ana­ lyses varies from devising suitable alignment procedures for main propulsion shafting right up to complete propulsion and shafting design studies. The work is being carried out in close conjunc­ tion with Lloyd’s Register’s Technical Investi­ gation Section, assisting, when required, with analyses, and taking advantage of the latter’s wealth of technical data ’feed-back’ accumula­ ted over many years of solving technical trou­ bles.

Voor allen die in deze ontwikkelingen belangstellen een aan te bevelen boek. De prijs in paperback is £ 3 5 .0 0 . ücii voigenu congies over ueze onuei werpen vinut plaats van OU september - 3 oktober te Parijs. Prof. ir. J. H. Krietemeijer ’Zeilstrijken - Stoom op’ door Jhr. Henri Reuchlin N.V. Uitgeverij Nijgh & Van Ditmar, 1975 Afm. 17 X 10 x 0 ,6 cm, 99 blz., 8 foto’s van portretten tussen de tekst. Prijs ƒ 7 ,5 0 . In de serie ’Roterodamum’ (een reeks boekjes over Rotterdam in heden en verleden, uitgegeven vanwege het Historisch Genoot­ schap Roterodamum) verscheen bovengenoemd werkje van de heer Reuchlin. Het bevat een lezing en de voorstudie ervoor die Reuchlin heeft gehouden voor het Historisch Genootschap in het kader van het eeuwfeest van de Holland Amerika Lijn. Het is een beknopte maar boeiende beschrijving van de oorzaken die ertoe hebben geleid dat in Nederland de overgang van zeilvaart naar stoomvaart zo vertraagd verliep in tegenstelling tot die in het buitenland. De activiteiten worden vernield van enkele belangrijke figuren, die vooral in de tweede helft van de vorige eeuw plannen voor belangrijke ondernemingen opstelden die echter veelal schip­ breuk leden door andere inzichten bij regeringsinstanties. Maar ook regionaal chauvinistische opvattingen deden afbreuk aan de ontwikkelingen van plannen. Het geeft voorts een goede indruk van de pol itieke en economische verhoudingen in die tijd met betrekking tot het scheepvaart­ bedrijf. Het boekje kan een goede aanzet vormen tot verdere studie over dit onderwerp, vooral door de uitvoerige referentielijst die is opgenomen en waarnaar op duidelijke wijze in de tekst wordt verwezen. Zeer aan te bevelen. Prof. ir. J. H. Krietemeijer