Monday, June 25, 2012

TANKCLEANING PROCEDURES, ON CHEMICAL TANKERS- CAPT AJIT VADAKAYIL



TANKCLEANING PROCEDURES, ON CHEMICAL TANKERS-  CAPT AJIT VADAKAYIL



Tank cleaning is usually done with water, unless the cargo ROB in tank creates a stubborn residue like Isocyanates, in which case a non-reactive solvent must be used. Isocyantes will form stubborn Urethane and CO2 gas in large quantities with water.

Esters and chlorinated HC will  slowly hydrolyse to acids. This is allright in epoxy tanks if the tank cleaning is uninterrupted at the prewash stage . SS can handle the pH of the acid.

It is most important to know the next cargo planned to be loaded . Washing to WW standard after a particular cargo is not as critical.

No cleaning can take place unless the mandatory prewash as required by MARPOL is done.

Substances with high VP can be removed from tank by evaporation, unless they leave a stubborn residue or contain inhibitors.  The NVM content of the chemical data sheet must be consulted. Any inhibitor not washed off will be difficult to remove and will have a bad influence on the next cargo or fail the WWT. Most inhibitors are fully soluble in water.

The master must enforce precautions like “ no smoking “ and “ AC on recirc “.  It is important for all on a chemical tanker to know the location of AC fresh air intake, and the Anemometer , to use the relative wind direction to advantage.  Bioaccumulative vapours and carcinogenic fumes can enter the engine room via intake vents and cause health problems for the engine staff. It is not all right to say that just the deck crew are exposed to toxic vapors.

Water washing can be done even if the solubility of the chemical in water is low to as much as 0.3%.  such solubility always increases if the water temperature is higher. Hence always try to use wash water at high temperature ( about 25 deg higher than MP after removing cold ballast interface ) unless the cargo being cleaned does not allow it, like drying oils and mineral oils with high paraffin content.  Solidified matter when melted flows away with the stripped out water, it need not be soluble.

Mineral oils with high paraffin content and certain crude oils which require heating during transportation should always be cleaned with ambient wash to prevent evaporation of lighter fractions which would leave a waxy residue on tank bulkheads.  

Drying oils if prewashed with hot water will polymerize. Drying oils must be washed immediately after dischg with ambient water. If they are left to dry polymerization takes place due to reaction with oxygen, and heat increases the reaction speed. This means by removing the air form the tank using Nitrogen this process can be slowed down. By the way, Ambient means upto 35 deg C. Moderate means upto 60 deg. Hot means >60 deg C. 

Certain cargoes like acetic acid, benzene, luboils, caustic soda, paraffin, molasses, phenol, DINP, fatty alcohols, HMD , Hitec, WPAC, butyl acrylate , creosote etc  can be hot pre-washed.

However if you hot prewash Styrene monomer or Acrylic acid polymerization will happen.  The hotter the water, the faster the polymerization. Due to condensation of vapour , inhibitor free liquid is formed, as the inhibitor is not volatile. Inhibitor if not removed will affect the PTT test.

When a cargo is fully soluble in water, using tank cleaning chemicals in a mindless manner does more harm than good.

Cleaning the tanks is just not enough. Most often it is the tank appendages which cause huge cargo claims or tank rejection. PV valves, vent lines, fixed pipelines , portable manifold hoses, superstrip lines, sampling and drain cocks, air/ nitrogen/ steam portable connection stubs, pump internals , cofferdams –all can hold contaminant matter. With certain cargoes like LSHW FO even the butterfly valve Teflon seals can trap sludge and discolor the next cargo.

Washing tanks with portable/ fixed Butterworth machines from designated areas may not clean everything. This is why it is important to enter the tank and have a visual check before wasting fresh water and expensive tank cleaning chemicals after high MP cargoes like palm oil fatty acids. As soon as you open the tank dome you get a general idea of shadow areas.

The chief officer must know if the tank corrugations are horizontal or vertical. Horizontal corrugations mean that fixed tank cleaning machines which cannot be given drops are ineffective. Vertical corrugations mean that the position of the butterworth port is important.

Some of the butterworth heaters may not be able to deliver the correct temperature and pressure in cold winter. In such case use lesser tank cleaning machines to get more temperature with correct pressure.

If the previous cargo is strong smelling like Acrylates or Crude Turpentine or MTBE a smell killer can be used. Gaskets emit smell, hence they must be flushed with methanol.

STAGES OF TANKCLEANING:--
1)        Precleaning with sea water.

Pre cleaning is different from MARPOL mandatory Prewash. Tank cleaning machines may have shadow sectors , and this can be rectified for main wash. Non drying oils and fats can be steamed before the hot water precleaning.

Pre-cleaning is the first cleaning step, without cleaning agents in order to remove the majority of product residue. The cleaning temperature and the temperature of the adjacent tanks are important parameters for successful cleaning. When water is not allowed , pre- cleaning is carried out with a suitable solvent. Pre-cleaning generally takes several hours and the sooner pre-cleaning is done after discharge, the easier it is to remove the product residue. Pre-cleaning is very important, because it is very difficult to obtain a satisfactory result following an initial mistake


2)        Main wash with sea water

Do not attempt to use tank cleaning chemicals unless the cargo clingage is removed.


3)        Tank Cleaning Chemical wash

If cargo is not water soluble or residues remain , the use of  tank cleaning chemicals is justified.  If the previous cargo is not water soluble using a 0.04% detergent wash will be good enough for WW standard ( this is not WALL WASH ).  Graco barrel pump injecting into the tankcleaning line , is the best as the bottom can be kept stripped and tank cleaning chemical is not reused.  Inject at the rate of 2 litres chemical per cubic meter of wash water.  Discharge from both sides of the manifold to Annex 2 UW overboard.

Recirc using spider / octopus will clean dirty areas, but they will also dirty clean areas.  Also if the solvent is volatile it will evaporate. Recirc is more effective after a Graco injection wash. Prevent static charge dangers. Annex 1 mineral oils which are not soluble in water requires a emulsifier/ degreaser wash. Handspray with undiluted  chemicals is only for local application , sufficient contact time must be allowed.

Most cleaning agents are additives which are used in combination with water to improve the water solubility of the cargo to be cleaned. Only very few cargoes which cannot be  cleaned  with  water-based systems  require  a  non-water-based solvent  as  a cleaner (sometimes in combination with an emulsifier).

To neutralize the odor of some chemicals, the use of an odor remover may be recommended in combination with an emulsifier. For most cargoes a variety of cleaning agents are available. Cleaning agents must be IMO-approved. Cleaning concentrations, times and temperatures in the final cleaning steps are recommended in the cleaning guides to achieve a satisfactory result. Cleaning generally takes several hours.


4)        Rinsing with sea water .

This is done with tank cleaning machines, the main purpose is to get rid of the residues loosened up by the tank cleaning chemicals.


5)        Flushing with fresh water

This is done with tank cleaning machine using a low throughput, to remove the salt before they dry up . If you anticipate a delay , as your ship does not have a dedicated FW pump or line prevent the salt from drying up by steaming, more so on zinc adsorbent porous surface.


6)        Steaming tank and pipelines ( to bring level of chlorides down and wash down appendages).

Steaming is the introduction of saturated steam into the tank to evaporate volatile residue (odour removal). The steam will condense on the tank surfaces. The temperature should normally be  as  high as  possible during steaming. This is enhanced if the adjacent tanks (including ballast tanks) are empty Steaming removes traces of volatile substances. The steam must hence be allowed to escape constantly via the PV valve.



If the chloride level of the wash water is too high, the use of steam for removal of chloride is often the only feasible option. Clearly the steam quality depends on the construction of the boiler.  If the steam is used to remove chloride, the wall temperatures should be cool (in contrast to the evaporation method described above) this results in condensation  and  water  film  running  down  the  tank  walls  to  wash  the chlorides off.



In case of Wall wash , with low chloride specs, for optimal results the chloride content of the water must be less than 0.1 mg/ litre  (distilled water, deionized water, demineralized water by microfiltration).


7)        Draining tank sump.

Strip out the tank and the pump stack. Sometimes it will be necessary to use a Wilden pump and sponges to save time.  Mopping reduces drying time if there are water pools on the tank bottom. Make sure no lint is left .


8)        Drying tank with ventilation.

While venting please remember that warm moist air condenses on a cold surface.  Ventilation removes water, moisture and odor, which is usually done by forced air circulation.



CAPT AJIT VADAKAYIL

29 YEARS IN COMMAND

..




20 comments:

  1. Hi Sir, i wanted to share some thing i saw yeasterday on TV --

    Tuborg

    This beer Brand was being promoted on TV which is owned by the Carlsberg Group.

    Clearly, many more Jewish brands are taking over this country from all directions.

    ------------------------------

    Same thing is happening with the TV channels, it has been made compulsory to use SET top boxes, and old TV sets do not support the latest technology.

    If you want to watch TV, but new TV's.

    It is the same bait and trap technique -- First get them hooked slowly, and then real in the web to make a massive profit.

    The only way to survive the web is to destroy the web, and the only one who can destroy the web is.....Kal Bhairava ( Rudra - Shiva the terrifying )

    He is the destroyer of the three dark cities -- Judaism, Christianity, and Islam.

    The true core is Judaism --because Crypto- Jews control "Christianity" and Islam from within.

    If the source is destroyed, then its Echo will be destroyed instantaneously.

    Neither Christianity, nor Islam are the true problem -- it is Judaism.

    ReplyDelete
  2. There are many proof's that can completely destroy the "source of all evil", Science is a perfect example too...

    Many of the constants used in Science and maths are Jewish names which proves that they stole all of our knowledge, and renamed it in their name..

    The point is that it is the same old story repeating itself....

    There comes a time in the universe when "Asuras" takes favor of "Brahma", and they ask for immortality...

    But, Brahma Says that no one can be Immortal in the world of death, however i can make the conditions of your annihilation very difficult.

    Using this gift from Brahma, the Asuras cause havoc in the world, and take every thing from the "Devas".

    The Devas go to Brahma for help, but Brahma says that they should talk to God Vishnu.

    When the devas, go to God Vishnu, he directs them to God Shiva....

    The devas go to God Shiva for help...

    God Shiva agrees to help, but certain conditions must be met before he can act to defend the people.

    Shiva comes in Human form

    He forgets who he really is, and he has to remind himself, who he really is and remember the purpose for which he was born....

    He has to fulfill those conditions so he can prove himself that he is Shiva, because any one can claim to be Shiva....

    Dear Sir,

    Do you know what those conditions are....?

    ReplyDelete
  3. hi druv,

    all religions preach love, fairness and compassion--

    --and this includes Christianity, Islam and Judaism.

    i have read the bible ( old testament and the new abdridged one ) and the koran.

    you should only be against the "middlemen" or "brokers" between man and the gods of these religions, who try to grab power -- the ultimate intoxicant, for their own selfish needs.

    these are "prostitutes of the soul"--who have killed millions of human beings on this planet in the name of religion. 90 million hindus have been killed by christianity and islam.

    yet our "not so bright" rahul gandhi goes crying to US senators , about hindu terrorism ( wiki leaks ).

    if you read my post ( put in google ) PROUD TO BE INDIAN , PROUD TO BE HINDU- VADAKAYIL, openness /oneness and inclusivity --is the essense of hinduism, and you need to be proud of that.

    for the vedic rishis had said there are many paths to the final goal.

    a true follower of sanatana dharma will NEVER EVER say that his religion is the best-- and he does NOT feel the compulsion to belitte and destroy other faiths.

    people all over the world are slowly realising this.

    grace and peace!

    capt ajit vadakayil
    ..

    ReplyDelete
  4. Brilliant post!.i love it reading of this excellent post. High pressure cleaning machines and High pressure washer India by all surface pressure cleaning your article has proved your hard work and experience you have got in this field. Really, i like the fact that you made it so easy for people like me to read. Thanks for a wonderful share.

    ReplyDelete
  5. Sir,

    Kindly advise on procedure for washing for methanol/ last cargo Gasoline.
    With special reference to Marpol annex 1

    ReplyDelete
    Replies
    1. hi cs,

      i do NOT take questions of tank cleaning, due to obvious reasons.

      however-

      wash with emulsifier + surfactant injected into wash water.

      steam tanks after FW rinse.-- ventilate.

      do wall wash test.

      punch into google search-
      WALL WASH METHOD CHEMICAL TANKERS VADAKAYIL

      capt ajit vadakayil
      ..

      Delete
  6. CH
    October 13, 2014 at 6:35 AM
    Respected Captain,

    What is special about Tamil Nadu?

    How come it is able to continuously produce word geniuses like Ramanujam, Subrahmanyan Chandrasekhar, C.V. Raman, A.R. Rahman, Abdul Kalam, Venkatraman Ramakrishnan, Viswanathan Anand, Illayaraja, etc?

    Even till recently the Chief Justice of India, the Finance Minister, the RBI governor are all Tamils?

    Is there any scientific reason behind this? Because no other region has produced such super genius people in such numbers.

    Regards

    ReplyDelete
    Replies
    #####################
    Capt. Ajit Vadakayil
    October 13, 2014 at 7:06 AM
    hi ch,

    i am sure if i were a lawyer, i will NEVER EVER become CJI.

    i am sure if i were an economist, i will NEVER EVER become finance minister.

    you want me to continue ?

    when i was on my training ship in mumbai with 250 other cadets ( two years ) -- the biggest TELUs ( oily and slimy ) and SNEAKS ( snitches ) became SCC ( senior cadet captains ) , CC ( cadet captains ) , CL ( cadet leaders ) etc.

    i used to be in the CAPTAINS MONTHLY BREAKFAST PARTY ( cadet with maximum negative marks for OFFICER LIKE QUALITIES ) -- to be chewed up for breakfast every month .

    i got an EXTRA FIRST in every subject --except OFFICER LIKE QUALITIES.

    now what are OFFICER LIKE QUALITIES-

    being a son of a bit#h, being a sneak, being a hypocrite, being a as$ kisser , being a leader who will sell out his team, being a back biter, being an informer , being the best in playing to the gallery.

    so, so--

    at the passing out parade --most of the cadets who got all PRIXES were leaders -- they all got BOOOOOEEEEED !

    I remember i got only one prize--for being the best REPORTER IN ENGLISH -- the claps I got from the entire hall still resound in my ears -- along with another ROC ( royal officer cadet -who did NOT care to become a sold out leader ).

    and mind you -- i was in every single team which made my TOP ( starboard fore top ) the champion TOP.

    i was a champion sailor, rower, signaller, marks in subjects, soccer team in both years --

    but i lacked OLQ ( officer like qualities ) of being a FU#KIN' SLIME BALL.

    so in my passing our certificate , after two years of training -- i had an EXTRA FIRST in all subjects -- except OLQ where i was third grade

    so i guess they held a special meeting and GRACED ME TO FIRST CLASS --a young 18 year old boy -- .TEE HEEE !

    AT SEA, THE SAILORS DO NOT CARE FOR YOUR FOUR STRIPES- THEY ONLY CARE FOR WHO YOU ARE--

    AT SEA PEOPLE WHO KNOW ME , OR HAVE HEARD OF ME -- OR SAILED WITH ME, WILL VOUCH--

    CAPT AJIT VADAKAYIL WAS A SLAVE MORE POWERFUL THAN THE MIGHTY FU#KIN' CAESAR -- BY LIGHT YEARS .

    this has now passed on to LORE -- never ti happen again in the annals of sea .

    am i boasting ?

    -- so be it !

    humility is NOT about having a low opinion of yourselves to please the JEALOUS party.

    see, this would have been part of my post-- GAMES CAPTAIN PLAYED--

    you made me reveal it prematurely --with your TAMIL PRIDE ! TAKE IT EASY !

    check out my training ship-

    https://www.youtube.com/watch?v=MwpFBPMtnj4

    https://www.youtube.com/watch?v=k0BxC3kFET8

    capt ajit vadakayil
    ..

    ReplyDelete
  7. CH
    October 13, 2014 at 6:35 AM
    Respected Captain,

    What is special about Tamil Nadu?

    How come it is able to continuously produce word geniuses like Ramanujam, Subrahmanyan Chandrasekhar, C.V. Raman, A.R. Rahman, Abdul Kalam, Venkatraman Ramakrishnan, Viswanathan Anand, Illayaraja, etc?

    Even till recently the Chief Justice of India, the Finance Minister, the RBI governor are all Tamils?

    Is there any scientific reason behind this? Because no other region has produced such super genius people in such numbers.

    Regards

    ReplyDelete
    Replies
    #####################
    Capt. Ajit Vadakayil
    October 13, 2014 at 7:06 AM
    hi ch,

    i am sure if i were a lawyer, i will NEVER EVER become CJI.

    i am sure if i were an economist, i will NEVER EVER become finance minister.

    you want me to continue ?

    when i was on my training ship in mumbai with 250 other cadets ( two years ) -- the biggest TELUs ( oily and slimy ) and SNEAKS ( snitches ) became SCC ( senior cadet captains ) , CC ( cadet captains ) , CL ( cadet leaders ) etc.

    i used to be in the CAPTAINS MONTHLY BREAKFAST PARTY ( cadet with maximum negative marks for OFFICER LIKE QUALITIES ) -- to be chewed up for breakfast every month .

    i got an EXTRA FIRST in every subject --except OFFICER LIKE QUALITIES.

    now what are OFFICER LIKE QUALITIES-

    being a son of a bit#h, being a sneak, being a hypocrite, being a as$ kisser , being a leader who will sell out his team, being a back biter, being an informer , being the best in playing to the gallery.

    so, so--

    at the passing out parade --most of the cadets who got all PRIXES were leaders -- they all got BOOOOOEEEEED !

    I remember i got only one prize--for being the best REPORTER IN ENGLISH -- the claps I got from the entire hall still resound in my ears -- along with another ROC ( royal officer cadet -who did NOT care to become a sold out leader ).

    and mind you -- i was in every single team which made my TOP ( starboard fore top ) the champion TOP.

    i was a champion sailor, rower, signaller, marks in subjects, soccer team in both years --

    but i lacked OLQ ( officer like qualities ) of being a FU#KIN' SLIME BALL.

    so in my passing our certificate , after two years of training -- i had an EXTRA FIRST in all subjects -- except OLQ where i was third grade

    so i guess they held a special meeting and GRACED ME TO FIRST CLASS --a young 18 year old boy -- .TEE HEEE !

    AT SEA, THE SAILORS DO NOT CARE FOR YOUR FOUR STRIPES- THEY ONLY CARE FOR WHO YOU ARE--

    AT SEA PEOPLE WHO KNOW ME , OR HAVE HEARD OF ME -- OR SAILED WITH ME, WILL VOUCH--

    CAPT AJIT VADAKAYIL WAS A SLAVE MORE POWERFUL THAN THE MIGHTY FU#KIN' CAESAR -- BY LIGHT YEARS .

    this has now passed on to LORE -- never ti happen again in the annals of sea .

    am i boasting ?

    -- so be it !

    humility is NOT about having a low opinion of yourselves to please the JEALOUS party.

    see, this would have been part of my post-- GAMES CAPTAIN PLAYED--

    you made me reveal it prematurely --with your TAMIL PRIDE ! TAKE IT EASY !

    check out my training ship-

    https://www.youtube.com/watch?v=MwpFBPMtnj4

    https://www.youtube.com/watch?v=k0BxC3kFET8

    capt ajit vadakayil
    ..

    ReplyDelete
  8. CH
    October 13, 2014 at 6:35 AM
    Respected Captain,

    What is special about Tamil Nadu?

    How come it is able to continuously produce word geniuses like Ramanujam, Subrahmanyan Chandrasekhar, C.V. Raman, A.R. Rahman, Abdul Kalam, Venkatraman Ramakrishnan, Viswanathan Anand, Illayaraja, etc?

    Even till recently the Chief Justice of India, the Finance Minister, the RBI governor are all Tamils?

    Is there any scientific reason behind this? Because no other region has produced such super genius people in such numbers.

    Regards

    ReplyDelete
    Replies
    #####################
    Capt. Ajit Vadakayil
    October 13, 2014 at 7:06 AM
    hi ch,

    i am sure if i were a lawyer, i will NEVER EVER become CJI.

    i am sure if i were an economist, i will NEVER EVER become finance minister.

    you want me to continue ?

    when i was on my training ship in mumbai with 250 other cadets ( two years ) -- the biggest TELUs ( oily and slimy ) and SNEAKS ( snitches ) became SCC ( senior cadet captains ) , CC ( cadet captains ) , CL ( cadet leaders ) etc.

    i used to be in the CAPTAINS MONTHLY BREAKFAST PARTY ( cadet with maximum negative marks for OFFICER LIKE QUALITIES ) -- to be chewed up for breakfast every month .

    i got an EXTRA FIRST in every subject --except OFFICER LIKE QUALITIES.

    now what are OFFICER LIKE QUALITIES-

    being a son of a bit#h, being a sneak, being a hypocrite, being a as$ kisser , being a leader who will sell out his team, being a back biter, being an informer , being the best in playing to the gallery.

    so, so--

    at the passing out parade --most of the cadets who got all PRIXES were leaders -- they all got BOOOOOEEEEED !

    I remember i got only one prize--for being the best REPORTER IN ENGLISH -- the claps I got from the entire hall still resound in my ears -- along with another ROC ( royal officer cadet -who did NOT care to become a sold out leader ).

    and mind you -- i was in every single team which made my TOP ( starboard fore top ) the champion TOP.

    i was a champion sailor, rower, signaller, marks in subjects, soccer team in both years --

    but i lacked OLQ ( officer like qualities ) of being a FU#KIN' SLIME BALL.

    so in my passing our certificate , after two years of training -- i had an EXTRA FIRST in all subjects -- except OLQ where i was third grade

    so i guess they held a special meeting and GRACED ME TO FIRST CLASS --a young 18 year old boy -- .TEE HEEE !

    AT SEA, THE SAILORS DO NOT CARE FOR YOUR FOUR STRIPES- THEY ONLY CARE FOR WHO YOU ARE--

    AT SEA PEOPLE WHO KNOW ME , OR HAVE HEARD OF ME -- OR SAILED WITH ME, WILL VOUCH--

    CAPT AJIT VADAKAYIL WAS A SLAVE MORE POWERFUL THAN THE MIGHTY FU#KIN' CAESAR -- BY LIGHT YEARS .

    this has now passed on to LORE -- never ti happen again in the annals of sea .

    am i boasting ?

    -- so be it !

    humility is NOT about having a low opinion of yourselves to please the JEALOUS party.

    see, this would have been part of my post-- GAMES CAPTAIN PLAYED--

    you made me reveal it prematurely --with your TAMIL PRIDE ! TAKE IT EASY !

    check out my training ship-

    https://www.youtube.com/watch?v=MwpFBPMtnj4

    https://www.youtube.com/watch?v=k0BxC3kFET8

    capt ajit vadakayil
    ..

    ReplyDelete
  9. Gud day sir,

    One word ur just great.......my qstn is will the same procedure can b used for tank cleaning after discharging phosphoruc acid .....wat additional steps have to be taken

    ReplyDelete
    Replies
    1. hi mv,

      http://ajitvadakayil.blogspot.in/2010/11/phosphoric-acid-on-chemical-tankers.html

      capt ajit vadakayil
      ..

      Delete
  10. Hi Capt. I read a lot from your blog especially when i'm searching over the net for chemical tanker operations. Could you please post on a list of safety precautions prior to and during tank cleaning in port.
    Thanks. Glinus Dmello

    ReplyDelete
    Replies
    1. hi g,

      http://ajitvadakayil.blogspot.in/2010/12/chemical-tankers-tank-cleaning.html

      capt ajit vadakayil
      ..

      Delete
  11. Sir can I get a link on sketch of a ramp door on a ro ro vsl

    ReplyDelete
    Replies
    1. http://www.ship-yacht-engineering.com/products-solutions.html

      Delete
  12. Capt.
    What is the regulation dealing with previous cargoes on a chemical tanker
    or banned cargoes
    for example: is it acceptable to load food grade sulphuric acid

    after the last cargo being a heavy oil

    ReplyDelete
  13. Capt
    What is the regulation on a chemical tanker
    or is it permissible to load a HFO over 0.995g/cm3
    and have the next cargo a food grade sulfuric acid for example
    is there a table which shows
    Annex 1 and annex II type cargoes

    ReplyDelete
    Replies
    1. file:///C:/Users/win7/Downloads/FOSFA%20Acceptable%20Previous%20Cargoes%20List.pdf

      http://ajitvadakayil.blogspot.in/2010/11/vegetable-oils-and-fats-on-chemical.html

      Delete
  14. good day sir,

    is that possible to clean cargo tanks by vetilating after gasoline so if it high volatile grade?

    thanks.

    ReplyDelete
  15. good day sir,

    is that possible to clean cargo tanks by vetilating after gasoline so if it high volatile grade?

    thanks.

    ReplyDelete