Wednesday, January 19, 2011

FREEZING WEATHER PRECAUTIONS ON CHEMICAL TANKERS --CAPT AJIT VADAKAYIL


Here in the picture below , you can see my ship ( Vishva Pallav in 1983 ) , negotiating sea-ice, in Chaleur Bay Canada, without ice class or ice bow.  I was on bridge for 3 days continiously, sitting next to the telegraph, with my wife bringing my toothpaste and brush on bridge in the morning. Till then she used to think a Captain's job is a bed of roses-- all wine and song and travel.


In the picture below you can see myself and my Chief Officer H Virendranath Hoige, planning an exit strategy from the Port of Belledune, considering the hull is NOT strengthened for ice and propeller is vulnerable.. In 1983, nobody made passage plans--we did it on our own.


The most important thing while navigating in pack ice is that Master must realise that the pivoting fulcrum of the ship moves to the bow rake .  So--when you give hard a port-- your stern moves to stbd, the bow remains there. Many inexperienced Masters have learnt this the hard way. 

Freezing conditions require RISK ASSESSMENT form to be completed and sent to the office in advance.

If you damage your ship in freezing weather, the reason is incompetence.

If your ship has unltagged steam pipelines and if you are constantly shipping cold seas, you may not be able to keep the cargo fluid. The ship can take a cumulative list and sink.

A chemical tanker has very low freeboard . The deck is cluttered with expensive tank attachments. Hardly any of them will be streamlined in case of rime. One devastating wave will do in the ship. Quite often the framo power pack is in the fore peak store. This means all hydraulic power is forward and if the ship has to even correct a list , or recirc cargo it may be difficult with the forecastle fully rimed.

Hot salt water hose jets at high pressure is the best way to cut  a swathe through the rime like hot knife through frozen butter ) .

If you have high VP cargoes forward whose PV vents get rimed, there will be structural damage. To prevent PV stack from freezing with rime, loose light canvas covers can be used. There are some cargoes like Stearic acid if they get frozen in the sample bottle the , white solid cargo rattles when shaken.

Don’t breach institute warranty limits without informing the insurance dept—just because “ocean routes advisory inadvertently advised you to breach it.

All FW and unused steam deck pipes have to the examined on its own individual three dimensional merit and drained at its lowest point. This is Chief Officer’s responsibility. If you do not do it with commonsense some valve body will crack. And be sure to change all river water FW ballast to salt water ballast.

If your vessel is required to force ice in the C/P ensure you do some homework--- if you do not have the requisite ice experience. Damages to bows/ propeller can cost the company a fortune.

Basic precautions: Follow relevant ones only , using your commonsense.

All space heaters for machinery on.
Antifreeze added to all radiators.
Header and hyd tanks oil heaters on.
Fresh water tanks heat or use adjacent heat
Keep sufficient bunkers in double skin
LO and HO purifiers to run continuously.
Stern tube cooling water tank slack.
DO filters cleaned more often to remove wax formation.
Maintain hotwell temperature for boiler
Change over to partial sea water recirc of full ballast tank recirc for cooling water.
Ensure air vents of ballast tanks are clear. It hardly takes a kilo of pressure to burst the tank.
Steam trace sensitive pipelines. Have sufficient copper tubes and thermal lagging.
Open steam to DO settling and service tanks. Maintain temp at 40 deg C.
Drain OWS
Bow thruster hyd oil heater put on 24 hrs before use.
Comply with machinery cold start recommendations in manual to prevent starting torque damage.
Keep steam injection hoses ready.
Open steam to sea chests and overboard as required.
Monitor suction/ dischg pressure gauges of SW pumps and inject steam if signs of ice is noticed.
Put up caution notices at local and remote starting points of various pumps whose drains are open.
Use plastic sheets to protect electrical equipment from condensation.
Note down how often the hydrophore cuts in cuts out. If it runs continuously investigate.
Isolate and drain all coolers of hyd systems.
Drain deck FW lines
Shut off veg room / lobby cooling and use portable heaters to maintain to +5 deg C.
Keep only low sea suction open .
Run clear view screens continuously.
Run radar scanners continuously
Keep ready salt, shovels, hammers, crowbars, fire axes, blow lamps etc ready.
It may be necessary to open manholes of ballast tanks while deballasting, ballasting.
Parcel sensitive pipes like bridge wash
Inlet valves for draft gauges to be closed.
Keep all bilges dry
Heat the accommodation interior. Do not open doors unnecessarily and allow heat to escape.
Drain all foam lines
Blow and remove water from  cargo heating coils of empty tanks.
Take sounding of peak tanks 3 times a day.
Grease PV floating lips, the mesh may get choked.
Critical pipes paint silver to retain the heat.
Bridge window wash cold water pipe cut off. Use only hot water. Run wiper blades slowly to avoid freezing of moving parts
Reduce rudder limit to 10 degrees on auto pilot .
For detecting bergy bits use radar on continuous trails and small range.
In pack ice use suez canal light.
If you put silver foil  inside your helmet or else where the body heat is retained.
Work with you back to the freezing wind.
Leave one hydrant open on the lowermost exposed deck.
Leave DO DB tanks slack.
Recirc hyd oil via thermal bypass.
Do not use steam hose to clear rime from Polypropylene hawsers on drum, cover with canvas..
Make sure all sensitive moving parts are greased liberally including winch handles, drain cocks and compressed air valves.
Drill holes on external spindle protection sleeves of manual valves.
Obtain phone/ fax/ telex/ email ID’s of local ice authorities.
Keep the ballast water level of wing tanks two feet below sea level.
In case of boiler breakdown ensure there is enough DO.
Do not use bow thruster in ice.
Use artic grade HSD in the life boats –if they are open.
There is a possibility that the hyd relief valve of the steering will lift.
When turning in pack ice remember that the sides of the vessel are weak.
Ensure that the propeller immersion is sufficient in pack ice—especially if the vsl is calling to dischg.
Ice navigation is the sole discretion of the master in consultation with ice authorities.
Blow water off compressed air line from the lowest point. Use dehumidifier in engine room. Blow whistle regularly in snow.
Cold start spray must be available in life boats.
In freezing rain the bridge portholes can get translucent/ opaque. It may be necessary to use portable heaters on bridge front glasses which do not have inbuilt heating.
Fill sounding pipes with antifreeze ( HO pipes with DO )
Make air coupling for sounding pipes
No recirc of air in the engine room must be allowed
Circulate fresh water systems
Maintain small flow of water through the sanitary system
Install a jumper line between supply and return of steam pipes.
Have more than usual bunkers and FW
In case you are rotating winches ensure greasing is done every 12 hours.
Frequent inspections to look for ruptured pipes.
Life boat engine water drained and space created for adding antifreeze.
Steering gear header tank heater on.
Stern tube cooling water tank slack.
Flow of cold air to machinery spaces to be reduced ( less fans and less dampers ) in the E/R by short circuiting air path between the skylight and the inlet vent.
Monkey island deck coated with silver to keep wheel house warm and comfortable. Use portable heaters o bridge
Funnel flaps shut when warranted to protect boiler and economizer.
Try out whistles frequently.
When vsl enters ice, log down the time and inform E/R.
Special briefing for bridge watch keepers and lookout men. How to identify old ice ridges and hummocks. Master on bridge all the time while in pack ice. Hence the necessity to pace himself like a marathon runner. Dropping out on reasons of fatigue before job completion means expensive damage or getting beset for a few days.
Officers to understand the concept of ship finding for itself path of least resistance with rudder amid ship.
Give wide berth to other ships in pack ice.
Freezing spray avoided by reducing speed / altering course. Keep Suez canal search light ready for night navigation through pack ice. If ship gets stuck use aft search light too.
Keep to beaten track in pack ice. Otherwise ice breakers who are short on patience will ignore you when stuck.
Use white coloured long johns and socks to preserve body heat. Make sure neck is not exposed.
If you feel numbness on cheeks and nose go indoors and get warm.
In case of boiler breakdown , have sufficient DO.
Keep bown down to keep ice off the thruster tunnel.
On unlagged steam lines it is all right to have a small steam leak to act as relief during hammer.
Procure Halogen lamps for use in spaces which do not have space heater.
The wheelhouse atmosphere must be warm and dry . not warm and moist. Otherwise the inner wheelhouse glass with get frozen and opaque. Avoid using kettle in the wheel house.
The forepeak tank must be filled above water level to act as a shock absorber.
It will be advisable to determine the melting point of heated cargoes yourself by using sample bottles. This will avoid unnecessary overheating on bad weather days with unlagged pipelines.
Chief officer must record how may turns the steam coil return valves are open for heated cargoes. Stow high MP cargoes aft.
Prolonged steam hammer even at night means bad management.
If you allow steam to return to E/Room from tankheating coils ,not water, your ship may deplete her safe bunker reserves
Remember black colour is a good radiator and a good absorber of heat. Silver colour on the contrary is a bad radiator and a bad absorber.
The most serious problem experienced during navigation in pack ice has been damage to propeller caused by astern movements.The trailing edge of a propeller has the thinnest section and is unable to withstand the additional forces when it suddenly becomes the leading edge running in ice. Physical edge damage and deformation/bending within the thinner section will cause severe overload of engine often accompanied by heavy vibrations.
At sea the fresh water tank for stern tube cooling should be checked daily that it remains liquid and in port it should be drained out and refilled prior engine operation.
Sufficient air space should be left in each FW tank. Upper manhole may be opened in order to break any ice that forms. Circulating of fresh water may be considered if freezing in tank or supply lines occurs.
Bunker line steam tracing should be used if fitted. Ensure settling and service tanks are full on arrival and maintain temperatures. Transfer if necessary from heated bunker tank and drain fuel line on completion.
In port one steering gear pump may be left running and rudder swung occasionally.
Resistance reading should be taken before starting any motor especially steering motors, deck machinery motors and those located at engine room lower level.
Apply heat to M/E to prevent freezing. Allow extra time to heat to minimum inlet  temperatures before manoeuvring.
Control air system drain regularly and every two hours in the period prior to departure.
Protect LB water rations
Keep all batteries fully charged.
Ensure the hyd system does not have water contamination. Use sand at slippery areas.

Note:
Freezing Point of FW is 0 deg C and sea water is -1.91 deg C

-------CAPT AJIT VADAKAYIL


           

3 comments:

  1. Dear Capt Ajit,
    I have read your post with great interest. In fact, I had never sailed in sub-zero conditions or in Ice but am writing Ice procedures for ships in my company. What an irony!!!!

    Anyways, job is a job. Your inputs are of great value to me. Do you have any inputs for control air for pneumatic equipments on board???

    Brgds
    Capt Sharma Naresh K.
    nareshsudha1@yahoo.com

    ReplyDelete
    Replies
    1. hi ns,

      control air for pneumatic instruments must be DRY ( dessicator) and filtered .

      most pneumatic automation problems on ships arose because of poor quality air.

      while certain pneumatic equipment needs a lubricator -- control air for automation cannot have oil vapor .

      nowadays on new ships we have PLCs and microprocessors -- pneumatic automation ( flapper and orifice type ) is almost obsolete , except in old model main engine automation for valves etc.

      capt ajit vadakayil
      ..

      Delete
  2. what are the freezing sprays ? hoe you will avoid it?

    ReplyDelete