4_Gas Tanker Types and Layout

7/26/2019 4_Gas Tanker Types and Layout

1/19

GAS TANKER TYPES AND

LAYOUT


2/19

Gas carriers can be grouped into six diferentcategories according to t e cargo carried andt e carriage condition! i"e"

(a) #u$$% pressurised s ips (b) Se'i(re)rigerated*se'i(pressurised s ips (c) Se'i(pressurised*)u$$% re)rigerated s ips (d) #u$$% re)rigerated LPG s ips (e) Et %$ene s ips (f) LNG s ips


3/19

Fully pressurised ships T ese s ips are t e si'p$est o) a$$

gas carriers in ter's o) contain'ents%ste's and cargo( and$inge+uip'ent and carr% t eir cargoes ata'bient te'perature" T%pe , tan-s (pressure .esse$s )abricated in carbon

stee$ /it a t%pica$ design pressureo) 01"2 barg! corresponding to t e.apour pressure o) propane at 32o,!

'ust be used"


4/19

Semi-refrigerated ships T ese s ips are si'i$ar to )u$$% pressurised

s ips in t at t e% incorporate T%pe , tan-s( in t is case pressure .esse$s designed

t%pica$$% )or a 'axi'u' /or-ing pressureo) 2(1 barg" T e s ips range in si4e up to1!255 '6 and are pri'ari$% used to carr%LPG" Tan-s on t ese s ips are constructed

o) stee$s capab$e o) /it standingte'peratures as $o/ as 705o," T e% canbe c%$indrica$! conica$ or sp erica$ in s ape"


5/19

Semi-pressurised/fullyrefrigerated ships

,onstructed in t e si4e range 0!255 to65!555 '6! t is t%pe o) gas carrier

as e.o$.ed as t e opti'u' 'eans o)transporting t e /ide .ariet% o) gases!)ro' LPG and 8,9 to prop%$ene andbutadiene" Li-e t e pre.ious t/o t%pes

o) s ip! SP*#R gas tan-ers use T%pe ,pressure .esse$ tan-s and t ere)oredo not re+uire a secondar% barrier"


6/19

T e tan-s are 'ade eit er )ro' $o/te'perature stee$s to pro.ide )or carriagete'peratures o) 73:o, / ic is suitab$e )or

'ost LPG and c e'ica$ gas cargoes or)ro' specia$ a$$o%ed stee$s or a$u'iniu' toa$$o/ t e carriage o) et %$ene at 7053o,"

T e SP*#R s ip;s


7/19

Fully refrigerated LPGships

#u$$% re)rigerated =#R> s ips carr% t eircargoes at approxi'ate$% at'osp ericpressure and are genera$$% designed to

transport $arge +uantities o) LPG anda''onia" #our diferent cargo contain'ents%ste's a.e been used in #R s ips?independent tan-s /it doub$e

u$$!independent tan-s /it sing$e side s e$$but doub$e botto' and opper tan-s! integra$tan-s and se'i('e'brane tan-s! bot t ese$atter a.ing a doub$e u$$"


8/19

T e 'ost /ide$% used arrange'ent is t eindependent tan- /it sing$e side s e$$/it t e tan- itse$) a T%pe A pris'atic

)ree(standing unit capab$e o)/it standing a 'axi'u' /or-ingpressure o) 5"1 barg" T e tan-s areconstructed o) $o/(te'perature stee$s toper'it carriage te'peratures as $o/ as 73:o," #R s ips range in si4e )ro' 05!555to 055!555 '6"


9/19

Ethylene ships Et %$ene s ips tend to be bui$t )or speci@c trades

and a.e capacities ranging )ro' 0!555 to 65!555'6" T is gas is nor'a$$% carried )u$$% re)rigeratedat its at'osp eric pressure boi$ing point o) 7053o," ) T%pe , pressure .esse$ tan-s are used!no secondar% barrier is re+uiredB T%pe C tan-sre+uire a partia$ secondar% barrierB T%pe A tan-sre+uire a )u$$ secondar% barrier and because o)

t e cargo carriage te'perature o) 7053o, t e u$$cannot be used as a secondar% barrier! so in t iscase a separate secondar% barrier 'ust be @tted"


10/19

LNG ships LNG carriers are specia$ised .esse$s

bui$t to transport $arge .o$u'es o)LNG at its at'osp eric pressureboi$ing point o) 70 6o," T ese s ipsare no/ t%pica$$% o) bet/een 0 5!555and 065!555 96 capacit% and are

nor'a$$% dedicated to a speci@cproFect / ere t e% /i$$ re'ain )ort eir entire contract $i)e! / ic 'a%

be bet/een 5( 2 %ears"


11/19

LA !"# !F A GENE$AL GAS%A$$&E$

Li+ue@ed Gas tan-ers are designed! bui$tand operated so t e% obe% ru$es andregu$ations" T ese ru$es and regu$ations

are de@ned b% t e Go.ern'ents o) t ecountries in / ic t e s ips areregistered! and are based on ru$es 'ade

nternationa$$% and reco''ended b%9O" T ese ru$es protect %ou! t e s ip!

t e en.iron'ent and t e cargo! and e$pto 'a-e t e operation sa)e"


12/19

t is not per'itted )or a cargo pu'p(roo' to be p$aced be$o/ t e upperdec-B nor 'a% cargo pipe/or- be runbeneat dec- $e.e$B t ere)oredeep/e$$ or sub'ersib$e pu'ps 'ustbe used )or cargo disc arge" ,argo

pipe/or- to tan-s beneat dec- $e.e$'ust be ta-en t roug a cargo tan-do'e! / ic penetrates t e dec-"


13/19

ere a gas tan-er is @tted /it are$i+ue)action p$ant! t is p$ant is

oused in a co'pressor ouse ondec-" ,ontiguous to t is co'pressor

ouse is an e$ectric 'otor roo'!/ ic contains t e 'otors )or dri.ing

t e co'pressors o) t e re$i+ue)actionp$ant and booster pu'ps / en @tted"A gastig t bu$- ead 'ust separate

t e e$ectric 'otor roo' and


14/19

T e 9O codes detai$ t e re+uire'ents )or 'ec anica$.enti$ation o) t ese roo's" Positi.e pressure.enti$ation 'ust be pro.ided )or t e e$ectric 'otorroo' /it negati.e pressure .enti$ation )or t e cargo

co'pressor area! t us ensuring a positi.e pressurediferentia$ bet/een t e roo's" An air$oc- entrance to t e e$ectric 'otor roo' )ro' t e

/eat er dec-! /it t/o gastig t doors at $east 0"2'etres apart! pre.ents $oss o) t is pressure diferentia$on entr% into t e 'otor roo'" To ensure t at bot doorsare not opened si'u$taneous$% t e% 'ust be se$)(c$osing /it audib$e and .isua$ a$ar's on bot sides o)t e air$oc-"


15/19

Gas tan-ers are @tted /it a @xed /ater spra%s%ste' )or @re protection purposes" T isco.ers cargo tan- do'es! cargo tan- areasabo.e dec-! 'ani)o$d areas! t e )ront o) t eacco''odation area! boundaries o) contro$roo's )acing t e cargo area! etc" n additionto t is @xed /ater spra% s%ste'! a$$ gastan-ers 'ust be @tted /it a @xed dr% po/derinsta$$ation capab$e o) @g ting $oca$ cargoarea @res" At $east t/o and ose $ines 'ustbe pro.ided to co.er t e dec- area"


16/19

S"$'&'AL %APA &L AN#AN* L!%A#&!N

T e 9O codes di.ide gas carriersinto )our categories! s ip t%pes G!

G! PG and G! / ic re


17/19

S ip t%pes G* PG and G can carr%cargoes / ic representprogressi.e$% decreasingen.iron'enta$ a4ards and t ere)oreprogressi.e$% $ess stringentconstructiona$ re+uire'ents in

respect o) da'age sur.i.a$ capabi$it%in t e e.ent o) co$$ision or grounding"


18/19

A )u$$% re)rigerated s ip! sa% /it T%pe A tan-s! designed )or LPG 'ustco'p$% /it t e re+uire'ents )ortan- $ocation and sur.i.a$ capabi$it%o) a categor% G s ip / ereas ase'i(re)rigerated s ip /it T%pe ,

tan-s carr%ing LPG can co'p$% /itt e re+uire'ents eit er o) a G or a

PG s ip"


19/19

#or t e $atter case t e T%pe , pressure.esse$s 'ust be designed )or a design.apour pressure o) at $east 1 barg!and a design te'perature o) not $o/ert an 722o," T e PG categor% ta-esinto account t e )act t at t e pressure

.esse$ design pro.ides increasedsur.i.a$ capabi$it% / en t e s ip isda'aged b% co$$ision or grounding"

4_Gas Tanker Types and Layout

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