Saturday, October 1, 2011

ACRYLONITRILE ON CHEMICAL TANKERS- CAPT AJIT VADAKAYIL




                ACRYLONITRILE


 

Cyano Ethylene, Propene Nitrile, Vinyl Cyanide.



Very reactive; may polymerize explosively in the presence of strong bases (such as caustic soda) , by heat or visible light. As the name suggests when heated, this material may evolve killer toxic cyanide gas, or explode, or both.  

Acrylonitrile is a known carcinogen.




Colorless mobile liquid to pale yellow

Clear and free from suspended matter

Very toxic

Known carcinogen

Mutagen/ changes hereditary genetic material of living cells

Odour/ sharp of peach kernel or garlic odour

SG/ 0.808

Chemical family/ nitrile

CHRIS code/ CAN

UN No/ 1093

Pollution category/ Y

USCG group/ 15

BP/ 77C

MP/ -83C

VD/ 1.83 (vapor can travel along the ground )

FP/ -1C

AIT/ 231C

AH/ nil

VH/ nil

VP/ 100mm HQ @8C

Viscosity/ 0.4 mPas

Surface tension/ low

pH/ 6 to 7.5 (5% soln )

Evaporates

Polymerises by heat. Polymerization can be initiated by visible light , so store in dark place.

AH/ ambient

Vapor pressure 20C (mmHg)/ 83C

Raid vapor pressure (psia)/ 3.5

Vapor pressure 46C (psia)/ 5.0

Vapor density (air =1.0)/ 1.8

Solubility in water/ partial

Flammable liquid

Can ignite on contact with certain oxidisers

When heated, this material may evolve toxic cyanide gas, or explode, or both. Flashback along vapor trail may occur. Fire may cause violent rupture of the tank.

Flammable limits/ 3.0 to 17.0%

Autoignition temperature/ 481C

Attacks natural and nitrile rubber

Soluble in organic solvents like Acetone, Toluene, IPA, Ether, Ethanol

Does not react with water.

Affects PTT and UV test of next cargo.



Vapor inhalation/ affects nervous system and lungs. Causes nose, throat irritation, tightness in chest, difficulty in breathing, nausea, dizziness, weakness, headache, impaired judgement, convulsions. Reassure the patient—do not leave him alone.



Cyanide kit:

12 pearls amyl nitrate

1 sterile syringe 10cc

1 sterile syringe 50cc

2 ampoules of sodium nitrate 10cc , 3% soln

2 ampoules of sodium thiosulphate 50cc, 25% soln.

Crush capsule in handkerchief and hold under nose. Do 5 times at 15 sec intervals.



Uses: nitrile rubber, grain fumigant, acrylic fibre, plastics, luggage , dinnerware



DO NOT use dry chemical for large, confined fire. If the tank is fitted with an N2 line, a fire may be extinguished by introducing N2. Water or foam may cause frothing. Keep tank cool with water spray. Fire-fighters must wear respiratory protection and full protective clothing including rubber boots.



Moderate irritating volatile chemicals, such that personnel will not usually tolerate moderate or high vapor concentrations.



Minimum hazards. Usually includes chemical which, if spilled on clothing and allowed to remain, will cause smarting and reddening of the skin with blisters and erythema. Wash with soap and flush with water.



Always use goggles.



Odor threshold (ppm)/ 21.4

Permissible exposure limits/TWA/ 29 ppm

Threshold limit value/TWA/ 2 ppm



Harmful by inhalation and skin absorption. Penetrates leather, liquid in shoes causes delayed bums. Contaminated leather shoes and gloves should be destroyed.



Eye irritation, headache, nausea, blueness of lips and finger tips. Contact with skin may also cause dermatitis.

STEL/ 400 ppm for 30 minutes



Penetrates leather. Contaminated leather gloves must be destroyed. Use butyl rubber gloves.

Inhibitor is MEHQ about 44ppm.(ethyl hydroquinone )/ 4 methoxy phenol (these are oxygen dependant, so do NOT inert tank )



Use PPE of PVC, neoprene, HD polyethylene



Remove victim to fresh air. If he is not breathing, apply artificial respiration. Remove contaminated clothing and wash chemical from skin with gentle flow of water. Get medical attention. If patient is unconscious, administer vapor of amyl nitrite (Break an Amyl Nitrite ampoule in a cloth and hold it lightly under the nose of the victim, but away from the person giving first aid, for about 15 seconds. Repeat five times at about 15 second's intervals).



Very reactive; may polymerize explosively in the presence of strong bases (such as caustic soda). The product must be inhibited to prevent polymerization. Polymerization could be initiated by visible light.

Copper and copper alloys are attacked and should not be used. Attacks aluminum in high concentrations Aluminum, Magnesium, Zinc, galvanized steel and Lithium should not come in contact with Acrylonitrile .  Materials normally used in electrical apparatus, such as copper, aluminum and insulation, should as far as practicable be protected to prevent contact with the vapor of Acrylonitrile.

Group 15.  See also exceptions to the chart (Do not stow adjacent to Caustic).



Wear rubber gloves, breathing apparatus, protective clothing. Avoid contact with liquid.

If leak on cargo transfer system, stop the transfer and empty the line system. Secure ignition sources. Flush contaminated area with a weak LAC solution (1%), then flush the area with large quantities of water.



Ensure inhibitor certificate is on board prior loading.



Chemical incompatibility Acrylonitrile/ Caustic soda solution

Experience has shown that there is danger of hazardous reaction between Acrylonitrile (group 15) and Caustic soda solution (group 5). This combination is considered compatible for adjacent stowage by current regulations (46 CFR part 160). While a review of the data used to construct the compatibility chart in these regulations showed no reactivity between these two chemicals at test temperatures up to 100 °C, the new data indicates that a delayed reaction may occur, which generates large amounts of heat if the mixture is vigorously stirred.  

DO NOT LOAD ACRYLONITRILE ( GROUP 15 ) AND CAUSTIC SODA ( GROUP 5 ) SOLUTION IN ADJACENT TANKS, AS AN EXCEPTION TO USCG COMPATIBILITY CHART.

Acrylonitrile is an unstable product when not inhibited. Acrylonitrile is regulated for bulk transportation by the IMO, BCH and IBC codes. Following is the summary of the codes' minimum requirements:

Alcohol resistant foam



REMOVAL OF ACRYLONITRILE FROM DRIP TRAYS

Any product that may enter drip trays when disconnecting the cargo hoses must be transferred to a slop tank or a toxic waste container by safe methods. Personnel must wear rubber gloves, face shield, plastic coated clothing and wear self-contained breathing apparatus. Small spills may be flushed away with water.



For washing: give cold prewash and then a hot wash.




-------CAPT AJIT VADAKAYIL
29 YEARS IN COMMAND

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