Tuesday, June 8, 2010

MDI -- DIPHENYLMETHANE DIISOCYANATE -- BHOPAL KILLER GAS -- CAPT AJIT VADAKAYIL


I have carried this chemical in huge quantities on Chemical tanker ships. 

UNION CARBIDE CORPORATION KILLED 25000 PEOPLE IN BHOPAL WITH MDI--- and maimed three hundred thousand human beings. 

After 26 years , dead souls got a pittance of 500 USD as compensation -- This is American "Agent Orange Justice" for you.  ( The Indian IPL cricket league is worth  4 billion USD ) 




Imagine if the 25000 dead were white skinned , instead of brown. 


Imagine the outcry and candle light vigils -- if the 3 00 000 maimed were seagulls or dolphins or right whales. 

What a disgrace!  

Read on to know more about the killer gas.

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TDI/ MDI / PAPI

TDI /MDI/ PAPI  are extremely poisonous as the name Cyanate suggests ---so take no chances,wear the correct safety equipment and do not try to rush the operation of this cargo at any stage. And if you don’t clean the tank properly it will leave a plastic layer tough to remove .


TDI ( TOLUENE DI ISOCYANATE)

REACTS VIOLENTLY WITH WATER GIVING OUT HEAT AND CO2, HENCE KEEP ADJACENT SBT EMPTY . 

Used for making flexible Polyurethane foams, Polyurethane coatings etc
Clear colourless to yellow liquid, darkens on exposure to sunlight
Sharp pungent sweet fruity odour
Carcinogen
CHRIS/ TDI
UN nuber/ 2078
FOSFA banned
Stainless steel stow
Flash point/ 132C
AIT/ 146C
Specific gravity liquid/1.21 @ 20C
Vapor density (air=1.0)/  6.0
Vapor pressure @ 25 C/  0.025 mmHg
IMO pollution category/ Y
USCG compatability/ Group 12
AH/ 50C
DH/ 35C
VH/ 30C
BP/ 251C
Visc at 20C/ 3 mPas
MP/ 19.5C
TLV/ 0.005 PPM OSHA
Odour threshold/ 0.4 ppm
Combustible
High surface tension
Highly toxic
Heat with thermal oil or adjacent heat
Must have Cyanide kit on board
Soluble   in organic solvents
Insoluble in water
Sinks in water
Gives NO2 gas when it burns
Reacts violently with acids, alcohols , bases , water, strong oxidisers and amines.
Carcinogen.
Risk of sensititation
Not detected by odour unless the conc reaches 10 to 20 times the exposure standard.
By skin absorption liquid is extremely harmful. Dermatitis occurs.
Exposure to low concentration can cause severe respiratory problems.
Vapour inhalation of low concentration can cause ASTHMA-like symptoms, sudden acute broncho spasm and Pulmonary Odema. Headache, Neurosis with depression and unconsciousness.
Reacts with moisture In air even at levels as low as 100 ppm, rapidly evolving unstable carbonic acid gases at sufficient rate to rupture cargo tank bulkheads. Insoluble polymeric Urea is formed.
Prolonged heating above 45 C may cause polymerisation.
Full protective clothing and self contained breathing apparatus when handling hoses,valves,connections.lank cleaning machines etc.
Fire protection/ Alcohol resistant foram, regular foam, water spary ( not into closes tank ), dry chemical

Although TDI is a hazardous material, the hazard may be minimized if appropriate precautions are observed Typically, there are four routes of potential exposure: inhalation, skin contact, eye contact and ingestion.

Inhalation of TDI vapors may cause irritation of the mucous membranes of the nose, throat or trachea, breathlessness, chest discomfort, difficult breathing and reduced pulmonary function. It is important to avoid exposure above the TLV to minimize the possibility of respiratory sensitization.

Tests have shown that the least detectable odor level of TDI is approximately 0.2-0.4ppm. This odor threshold is significantly higher than the OSHA Permissible Exposure Limit (PEL) of 0.02 ceiling. If an individual can smell TDI, overexposure has most likely occurred. Airborne overexposure, well above the PEL, may result additionally in eye irritation, headache, chemical bronchitis, asthma-like findings, or pulmonary edema. TDI has also been reported to cause hypersensitivity pneumonitis, which is characterized by flu-like symptoms, the onset of which may be delayed.

Control of TDI exposure to the recommended guidelines (0.005 ppm as Time-Weighted Average, 0.020 ppm as Short Term Exposure Limit) is believed to protect against sensitization. However, if an individual has become sensitized to TDI, an asthma-like response may then result from very low exposures to TDI. In the event of skin contact, wash thoroughly with soap and flowing water for at least fifteen minutes (A recent study has indicated that corn oil or polyglycol-based cleaners may remove MDI more effectively than soap and water, and this may also apply to TDI.(5) Cleaning soon after contamination was also important.).

Promptly remove all contaminated clothing (including shoes) while washing. If the skin is burned or irritated, seek medical attention. Decontaminate clothing prior to re-use by soaking the garments in an 8 percent ammonia solution for one hour prior to laundering with hot water and detergent. Destroy all contaminated leather items including shoes, belts, and watchbands.

The  easiest and most convenient way to handle spilt TDI is to react it with polyol to produce a
low-quality foam, which then can be sold or used as a manufactured product. (CAUTION: The TDI/polyol reaction is exothermic, which may cause spontaneous combustion.)

Empty TDI drums can be decontaminated by filling them with water or a decontamination solution (5-10% sodium carbonate) and allowing them to stand unsealed for at least 48 hours. WARNING: Under no circumstances should empty drums be burned or cut open with a gas or electric torch, as toxic decomposition products may be liberated.

The use of suitable respiratory equipment is required whenever there is a potential for exposure to airborne TDI levels in excess of permissible exposure limits (PEL 0.02ppm-ceiling, TLV 0.005ppm - 8hour TWA).

RESISTANCE; ALWAYS CONSULT CARCO HOSE RESISTANCE LIST.

Following hose material is resistant to TDI

Butyl rubber
Polyethylene
Viton rubber
Teflon ( Hostaflon )

Chemicals Needed for Cleaning/Personal Protection

Low moisture content Chlorinated Solvent MEC (Methylene Chloride ) MARPOL   (  Y ) , or Trichloroethylene ( Y) or,  Perchloroethylene (  Y ) approx 8-10 M3 per tank,  charterer will supply. If using Methylene chloride ( Dichloro methane ) you will need 15 cum as its evaporation rate is more. Its BP is 40C and SG is 1.34. Some coatings like Phenoline and Devchem 253 are not resistant to MEC.

Sufficient TOLUENE for TDI line filling, say 200 Ltrs for each hose length x 2  (loading and discharging)

Cyanide kit:
12 pearls Amyl nitrite.
2 ampoules Sodium Nnitrite 10CC 3% solution.
2 ampoules Sodium Thiosulphate 50CC 25% solution.
Crush Amyl Nitrite capsules 5 times at 15 second intervals and hold under nose of a gassed victim.

200 Ltrs Aqua Ammonia
200 Ltrs IPA 30% (Iso propyl alcohol)—to use as solvent if TDI falls on skin.
Two litres of 1% Tincture of Green Soap
In case of spill first neutralize it with 50% Ethyl Alcohol, 40% water and 10% conc Ammonia.   If spill is small mix with sand or Sodium Bicarbonate. Pack it in a cardboard box and burn it in an open pit using paper as fuel.

EXTRA EQUIPMENT NEEDED:

Sufficient extra hoses (not ships normal hoses) and/or SS pipe  enable reach manifold area from pumpstack.

Two SS Spool pieces each with one inch drain valve fitted. ,

Two SS portable valves for the pumpstack.

Prior to Loading:

TDI, Clean tank to water white plus standard

Pressure test heating coils for leaks, then air blow water condensate from coils, followed by nitrogen blowing to ensure moisture free.  Blank off both inlets and returns. The cargo is water reactive and hence ensure NO water comes in contact.

Check/test function of PV Valve

Air blow PV vent line to ensure no water trapped in Line (especially if slight list or trim).

Mop dry cargo pump deepwell.

Pressure test cargo pump cofferdam. Purge out cofferdam with nitrogen and fill completely with DOP             ( Dioctyl Phthalate which has a VD of 13.5). 

Fit pressure gauge to vent line so tank pressure can be monitored during loading, voyage and discharge.

Prepare/connect vapour return system.  Calculate Pressure Drop.

Prepare 200 ltrs of neutraliser in case of spills:
80 ltrs freshwater, 100 ltrs IPA Iso propyl alcohol , 20 ltrs Aqua Ammonia.

Prepare a solution of 99% IPA and 1% Tincture of Green Soap for personal protection.

Loading  TDI or MDI

Cargo tank will be purged with Nitrogen to minus 40 deg C dew point or 0.25% by shore and pressure may be as high as 10 bars, therefore leave tank cleaning hatch and ullage hatch open as well as PV valve to ensure whole system is purged and tank does not have structural damage due to over pressurization.

When nitrogen purging is complete and shut down, secure the tank and put PV valve in normal operating position.

Ensure safety shower in operation.

Draeger tubes must be ready for use around the cargo area. Tape off and cordon the loading area.

When shore ready to start.  Open valves at shore connection and pumpstack.

For TDI you cannot do open ullaging or sampling.

         On Completion Loading

Shore will blow line with nitrogen to tank.
Close all valves and disconnect shore hose and vapour return.
Samples must be taken with closed sampling device.
Fill ships hoses with Toluene using Graco pump. Leave the Toluene inside for 3 days.
Wash hoses with warm water 50-60 C and steamed out and drained. 

Voyage

Heat as per charterers instructions by Adjacent Heated Cargo ONLY, unless ship has thermal oil heating,( TDI Normally 35 C ). Do not allow the temp to go below 21C or >45C
Do NOT have any cold ballast in the double skin.
Maintain nitrogen blanket at positive pressure, minimum 50 mb.

Discharging

Use vapor return hose . DO NOT DISCHARGE without vapour return hose.
Inert with N2 while discharging.

Cargo hoses to be blown with shore nitrogen at end of dischg. Fill Chlorinated solvent via manifold from storage cargo tank.

Pre-Cleaning

Chlorinated solvent 8-10 M3 of moisture spec <400ppm should already have been loaded into clean extra-dry tank and heated to 30-35 C for TDI ). The chlorinated solvent has to be heated to >MP of the Isocyanate, but

Prepare 2 SS tank cleaning machines and TDI resistant cleaning hoses.

Release ullage hatch but do not lift open, open PV valve. (in case of rapid pressure increase when solvent added.)

Transfer this solvent to cargo tank via manifold and through cargo hoses with pumpstack valve closed initially to ensure line is totally filled, then opened fully until all solvent transferred into tank.

Disconnect cargo hose from pump stack and connect blind flange with Y for tank  cleaning hose to fit.

Place machines in tank and cover opening to stop any liquid splashing out.

Commence circulation full strength for minimum two hours. Shore to supply Nitrogen continuously during circulation. At this time reconnect shore line (or shore slop line) to ships line ready for use.

After circulation, disconnect blind with Y and reconnect ships hose to pumpstack, and pump out to shore the Solvent TDI slop. After stripping blow line again with nitrogen, Stop shore nitrogen to tank and batten down tank until at sea.

When shore hose finally disconnected, fill ships hose/line again with chlorinated solvent as previously done.

NOTE: IF SHORE IS UNABLE TO ACCEPT THESE CATEGORY  Y  SLOPS AND THESE ARE BEING TAKEN TO ANOTHER PORT FOR DISPOSAL, REMOVE TANK CLEANING MACHINES AND BATTEN DOWN TANK TO AVOID MOISTURE ENTERING. 

SLOP SHOULD NOT BE CARRIED FOR LONG PERIODS AS POLYMERISATION CAN OCCUR.

Cleaning at Sea

After the solvent wash—wash the tank with water and detergent as if the solvent was the last cargo. .Make the entries in the Cargo record book.

Blow out cargo hoses, rig tank cleaning machines.

Blow out DOP from pump cofferdam (overboard) and flush with MEC then blow dry with nitrogen.
          
If some Methylene chloride is left in the sump put some Methanol into the tank and keep heating coils crack open.

First give a cycle cold sea water wash, but above the MP of TDI which is 19.5 deg C.

Then Hot wash tank for 2 hours with sea water.
Give FW rinse .
Steam tank for 2 hours, then mechanically ventilate for 3 hours.

Test tank with Draeger tube before entering to inspect.
TDI is a bad previous cargo for PTT and UV test.

There may be some tough brownish film residue or URETHANE layer ( moisture effect ) which is difficult to remove. Scour with 3m Scotch brite abrasive pads.  You may find polymerised bubbles with liquid cargo underneath and will need to neutralise.

TDI and MDI are extremely poisonous so take no chances, wear the correct safety equipment and do not try to rush the operation of this cargo at any stage.

If Gasoil is used for cleaning ( for TDO only ) , make sure the moisture is <400 ppm at 10 Cum per tank.. Recirc Gasoil for 2 hrs. Toluene can be used for line cleaning.  4 parts of Gasoil are required to dissolve 1 part of TDI.

Loading Arrangement

MANY LENGTHS OF CARGO HOSES WITH PORTABLE VALVE TO BE RIGGED FROM PUMPSTACK HOLE TO SHORE MANIFOLD .  DO NOT LOAD THROUGH FIXED SHIPS CARGO LINES . OTHERWISE POLYMERISATION / PLASTIC IN LINES WILL OCCUR.
 

Additional equipment required:

2 x portable valves
1 x blind pumpstack valve
2 x SS spool piece with drain valve 1 inch for blowing line and filling hoses with chlorinated solvent after load.
SUFFICIENT NUMBERS HOSES TO REACH CLOSE TO MANIFOLD AREA.


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MDI (DIPHENYLMETHANE DIISOCYANATE)

Characteristics  MDI

Used for making rigid foam.
CHRIS/ DPM
Dark coloured liquid with faint tarry odour.
MP (pure)/ 37.2 deg C
Specific gravity (liquid)/ 1.197 @ 70 deg C,
BP/ 196C
Coefficient of expansion/0.00098 per degree C
Vapor density (air= 1.0)/8.5
Vapor pressure @ 46 C/very low---0.00009 mm HG @25C
IMO pollution category/ Y
USCG Compatability/Group 12
UN number/2489
AH/ 60C
DH/ 45
VH/ 39C
TLV/ 0.05 ppm
FP/ 218C
MDI is not water soluble. Sinks in water
Viscosity 12 mPas at 40C
FOSFA banned

Incompatible with strong oxidizing agents.

Reacts violently with acids, alcohols and strong acids.

If inhibited by Ammonia do not stow in zinc tank ( pH >9 ).

Solubility, - soluble in Acetone and Kerosene

Flammable at high temperatures. Fire will cause polymerization and dangerously high pressures.

Reacts slowly with water producing C02,(Carbon dioxide),

Vapor is strong irritant to eyes and throat causing eye and lung injury, even low concentrations cannot be tolerated. On heating MDI gives toxic vapors of Carbon Monoxide, oxides of Nitrogen and Hydro Cyanide gas with very high VP.

REACTIVITY: MDI is unstable in traces of moisture, slowly forming C02 gas (carbon dioxide)

SAFETY: Full protective clothing and self contained breathing apparatus when handling hoses,valves,connections,tank cleaning machines.

Heat as per charterers instructions by Adjacent Heated Cargo ONLY, unless ship has thermal oil heating,

Fill ships hoses with chlorinated solvent like Perchloroethylene or Methylene chloride for MDI,
say 200 Ltrs for each hose length x 2  (loading and discharging)

At normal unloading and storage temperatures, MDI has a relatively low vapor pressure. With adequate ventilation, airborne MDI vapor concentrations are unlikely to reach or exceed exposure guidelines.

Nevertheless, at elevated temperature, or if MDI is aerosolized by compressed airblow , health problems will result.

Inhalation of MDI may cause irritation of the mucous membranes of the nose, throat or trachea,
breathlessness, chest discomfort, difficult breathing and reduced pulmonary function. It is important to avoid exposure above the TLV to minimize the possibility of respiratory sensitization.

Overexposure well above the PEL may result in eye irritation, headache, chemical bronchitis, asthma-like symptoms or pulmonary edema. Diisocyanates have also been reported to cause hypersensitivity
pneumonitis, which is characterized by flu-like symptoms, the onset of which may be delayed. Skin contact may result in an irritant or allergic contact dermatitis and may play a role in respiratory sensitization.

Skin staining or discoloration may occur. Long term contact may cause redness, swelling and blistering. Control of MDI exposure to the recommended guidelines (0.005 ppm as Time Weighted Average, 0.020 ppm as Ceiling) is believed to protect against sensitization. However, if an individual has become sensitized to MDI, an asthma-like response may then result from very low exposures.
The ACGIH TLV for MDI is 0.005 ppm (0.05 mg/m3) as an 8-hour Time Weighted Average (TWA). OSHA requires that exposures be controlled to below a PEL of 0.02 ppm (0.2 mg/m3) as a ceiling, to prevent lung tumours.

In the event of skin contact, wash thoroughly with soap and flowing water ( corn oil or polyglycol-based cleaners may remove MDI more effectively than soap and water. Decontaminate clothing prior to re-use by soaking the garments in an 8 percent ammonia solution for one hour prior to laundering with hot water and detergent.

When transferring MDI, personal protective equipment should be worn by crew engaged in cargo work, tankcleaning
This may, depending upon conditions, consist of:
• Chemical goggles;
• Face shield;
• Chemical gloves, resistant to MDI
• Long-sleeve coveralls or full body suit, resistant to MDI
• Fitted boots made of material  resistant to MDI, and;
• Head protection, such as a close fitting hood, made of a material resistant to MDI.


PAPI ( POLYETHYLENE POLYPHENYL ISOCYANATE )

UN number/ 2206(i) 2207
MARPOL category / Y
Maintain temperature between 24C and 40C. Do not allow the temperature to go below 18C r> 32C
CAS / 9016-87-9 0.1-0.5   
OSHA-PEL /  TWA- Ceil- 0.020      
ACGIH-TLV /  TWA- 0.005 ppm STEL

CAPT AJIT VADAKAYIL ( 28 years in command )-- POSTED IN PUBLIC INTEREST.
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5 comments:

  1. Dear Captain,

    It is not fair to compair MIC (Bhopal gas)and MDI because they are total different chemicals.

    MIC (methyl isocyanate, C2H3NO) is a liquid with a very high vapour pressure; 46.000 Pa, molar mass 57 g/mol

    MDI (methyl difenyl diisocyanate, C15H10N2O2) is a liquid with very low vapour pressure; 0.1 Pa, molar mass 250 g/mol and classified as harmfull.

    ReplyDelete
  2. Hey... You have nice Blog.. Keep follow this excellent work
    Cloudpoint Solutions

    ReplyDelete
  3. Dear Sir,
    we have a situation in one of our stainless steel chemical tanker where cargo has got polymerized on the bulkheads. Can you suggest any solvent or cleaning chemical that might be useful in removing this polymerized cargo

    ReplyDelete
    Replies
    1. hi u,

      use strong alkali and then strong acid - only if tank is SS. after that wash and use HP water jets -fish blade.

      if lining is epoxy paint-- grind and repaint.

      capt ajit vadakayil
      ..

      Delete
  4. Namaskar Captin, People often say, BHOPAL was a test. Do you agree?

    ReplyDelete