handling lpg and ammonia cargo

7/26/2019 Handling LPG and Ammonia Cargo

1/4

Handling LPG and ammonia cargo - preparation for loading

preparation for loading

(1) LPG is loaded through the manifold by using different liquid linesfor propane and butane into each allotted tanks by way of fillingvalves in the bottom.

() !s the tank pressure rises in the process of loading" cargo isloaded with gas inside being drawn out by using compressorsthrough the vapor suction on the top of each tank" and thenreturned to cargo tanks in the form of liquid after reliquefying by

the reliquefaction plant on board.

Operating Method

(1) !ir purge and leak test of loading arms in the manifold section.!ir is purged from the loading arms" and at the same time leaks

from the loading arm connections are checked" in either of thefollowing two methods after their connection" and it is confirmedthat the o#ygen concentration is less than 1$.

i) %itrogen gas is in&ected at the roots of loading arms on the shoreside and air is purged from manifold drain valves on the vessel andthe concentration of o#ygen is measured. 'y the in&ection ofnitrogen gas pressure is applied on the manifold section and leaksfrom the connections are also checked.

ii) ! drain hose of the shore side is connected to the manifold drainvalve on the ships side and air is purged by making use of remnantpressure in the loading rm through the following route loading arm*+ manifold *+ drain valve *+ drain hose *+ shore. ,heconcentration of o#ygen is measured on the shore by checking gasdischarged from the drain hose. !s the remnant pressure is used"


2/4

the pressure is not so high to conduct a leak test.

iii) !ir is pushed out from manifold drain valves on the ships sideinto the atmosphere by the remnant pressure in the loading arms.

-n this case flammable gas is discharged on to the upper deck" anddue caution is necessary to remove ignition sources.

iv) 'y supplying inert gas into the manifold through an inert gas lineand releasing gas into the atmosphere from drain valves" the vesselcan purge air by herself.

() ooldown of liquid lines and arms and leak checks of lines

/hen the cargo loading operation begins" liquid is transferred at a

very slow rate thereby pre0cooling liquid lines and enabling leakchecks. !fter confirming that the temperature of liquid lines are inthe order of below 02 in the case of propane and 3 degree inthe case of butane" and no abnormal condition is observed" thecargo loading rate should be increased in sequence.

() ,rim during loading operations

/ater ballast is discharged as the loading operation is in progress"

and such operation should be carried out so that no e#cessivestresses may be imposed on the hull and that no e#cessive trim iscreated.

(4) ,ank pressure during loading operations

/hile loading" care is required to keep the tank pressure constant ata specified value.

(2) 5isposal of remaining liquid and disconnection of loading armsafter completion of loading

!fter completion of cargo work" remaining liquid in the loading armsis disposed of in one of the following manners6 and the armdisconnecting operation is carried out after checking to see that theconcentration of flammable gas is 1 7ol $ or less.


3/4

i) 8ethod by which liquid and gas are pushed into the lines of thevessel by introducing nitrogen gas from the shore side. -t is amethod by which nitrogen gas is introduced at the roots of loading

arms on the shore side to push remaining liquid and gas into crossover lines" and the following checks are made through drain valves whether liquid still remains or not6 and the concentration ofremnant gas.

ii) 8ethod by which remaining liquid is discharged into the sea /iththe manifold gate valve closed" a plastic hose is connected to themanifold drain valve" and is then led into the sea water overboard6through the hose remaining liquid is discharged into the sea. !t thisinstant the end of the plastic hose should be slightly put into the

sea6 it should be ad&usted so that it may not be placed too deep orabove the sea surface.

iii) 8ethod by which nitrogen gas or inert gas is let in from themanifold drain pipe to push liquid to the crossover line of the vesseland to purge gas via the inert gas line into the vapor line. ! shore

pipe line is connected with the manifold liquid drain pipe throughwhich nitrogen gas is supplied to press remaining liquid intocrossover lines of the vessel. !fter disposing of the remaining liquid"gas is purged on to the shore by sending remaining gas throughvapor lines via inert gas lines.

Related Information:

1. General precautions and instructions for gas carrier

. argo machinery room safety precautions
http://www.liquefiedgascarrier.com/general-precautions.htmlhttp://www.liquefiedgascarrier.com/cargo-room-precautions.htmlhttp://www.liquefiedgascarrier.com/cargo-room-precautions.htmlhttp://www.liquefiedgascarrier.com/general-precautions.html


4/4

. ,o#icity and associated health ha9ards in liquefied gas carrier

4. Liquefied gas cargo handling equipment

argo -nformation 0 physical and chemical properties necessary for

the safe containment of the cargo

:afety guideline for changing previous cargo

'oil0off ; 7apori9ed Gas ('7G) 8anagement :ystem for L%G cargo

Liquefied gases 0

handling lpg and ammonia cargo

Documents