Dear Sir,
We(2E/3E/4E) would like to explain MT Virgo vessel Boiler deformed problem.
We loaded the RPS cargo all the tanks & went to the China for discharging.The cargo needs the temp
of about 80°C & we need to use the boiler for cargo heating along the way to China.Firstly,we would
like to explain about MT Virgo Boiler cascade tank.The cascade tank is the enclosed type &only have
one sight glass,(shown in Fig 1) & one level gauge.The cascade tank don’t have the manhole in the
upper side & we cannot checked the water condition easily.
We can check the water level from level gauge,but cannot check the condition of water easily
because of the sight glass made with the plastic.At the docking on May 2020,we ordered the new
sight glass,but only received the plastic sight glass.But during the cargo heating time we cleaned the
boiler water feed pump strainers every watch & checked the condition of water every time .
On 07 July 2020 before discharge the cargo,at the China anchorage,we found that the boiler watere
was contaminated with the cargo.So we stopped the cargo heating immediately,& checked all the
cargo heater from the cargo heater drain cock first.We suspected 2-3 cargo heater tubes were
leakage.So we decided to open up & check all heater tubes.We checked all the heater tubes the
whole night & found that 2P cargo heater tubes leakage.We rectified the leakage & drained all water
from the cascade tank.
We also drained the water from the boiler until the low low water level alarm coming.So we sure
that these alarms are in normal working condition.Also we realized that we need to drain all the
water from the boiler & to clean the boiler water level sensor.But we don’t have the sufficient time
because of the ship manoeuvring & the cargo discharging.So we need to start the boiler as fast as
possible because of RPS cargo need heating up 80°C & cold weather condition.We made the
chemical dosing (liquid coagulant) & (sucm & bottom) blow-down @ every watch as per office
instructions.We started again the boiler for cargo heating & run continuously until the cargo
discharge.
After discharge,we started the tank cleaning operation.We also continued the chemical dosage &
blow-down every watch as less as possible the cargo contamination in boiler.In tank cleaning
operation time,we cleaned the boiler feed water pump strainers every watch & monitored the
condition of the boliler water.At that time,we also checked the local boiler water level gauge glass &
the water level indicator from the control panel.We also drained & checked the local water level
gauge glass and found that this is in normal working condition.
On 15th July 2020during the tank cleaning time1400 LT,the boiler exhaust gas high temp alarm
coming & stopped automatically.We checked the main burner nozzle & cooled down the boiler
about 5mins.We started again the boiler ,reduced the fuel/air ratio & checked the smoke
condition.After 4 hrs ,we noticed that the cascade tank need to fill the water more than normal
condition & we found that the white smoke coming from the funnel.We checked from the furnace
inspection hole & found that the water leakage from the upper side of the furnace.So we informed
to the bridge,stopped the boiler immediately.Then we stopped the main engine & opened up the
burner.At that time,we found that too much water coming from the water tube of boiler furnace
upper side.We pumped out all the water .But the furnace was already deformed.
We informed to the office,opened the water side manhole & drain the remaining water for cooling
down.Then we checked & found that too much cargo residues coated on water tubes,smoke tube &
furnace wall.We found that the three water tubes upside of the furnace were leakage.We plugged
the three leakage tubes & informed to the office.
So we think the boiler furnace deformed because of the cargo residues coated the heat transfer
layers(furnace wall,water tubes & smoke tubes).So heat cannot tranfer to the water & the furnace
wall suffered the excessice heat & deformed.
2E 3E 4E
Zaw Myint Thein Htet Ahkar Soe Win Aung Pyae Thein
