Friday, November 26, 2010

METHANOL SPRAY ON CHEMICAL TANKERS-- CAPT AJIT VADAKAYIL

METHANOL SPRAY IS THE BIGGEST BULLSHIT GOIN' ON AT SEA--

so--what are you doing? 

you just spray methanol where ever the surveyor who will do wallwash,  can physically reach!   -- as he is NOT a bird--

so you have pre-empted the medium in his squirt bottle. All the muck is brought down to the bottom. The wall wash of the tank bottom is usually never done. 

but all this extra smartness can undo you-- if you fail the first foot.

it is better to fail the wall wash than the first foot.

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A Chemical tanker sailor at sea must care for his OWN safety.

His ignorant Captain and rogue Shipmanagement Company , will force him to spray Methanol using SCBA sets .

Remember, SCBA is for rescue from enclosed spaces, after an Emergency Alarm of 7 short one long blast-- -- NOT routine work inside cargo tanks ( like Methanol spray ).

In the IBC code , " working time " has been erroneously read by vested interests as official sanction to do routine WORK inside chemical cargo tanks.

IT IS NOT SO.

" WORKING TIME " IS TO BE READ AS " LUNG DEMAND TIME "

-- WHICH IS 100 LITRES OF FREE AIR A MINUTE FOR STRAIN ( OF FIREMANS LIFT RESCUE) , 30 LITRES A MINUTE FOR LIGHT ACTIVITY , AND 10 LITRES A MINUTE WHILE AT REST.

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GUIDELINES FOR METHANOL SPRAY

First of all secure all ingnition sources --as the fumes can travel.  Many chemical tankers had explosions while Methanol spray-- the bodies were NEVER found in one piece.

Methanol is NOT a static accumulator, like Toluene.  Toluene must NEVER EVER be sprayed!

Methanol spray requires a Risk Assessment form to be filled in conjunction with a Enclosed spaces entry form--and signed.  Do it on the Matrix of SEVERITY  to PERIOD OF IMPACT/ CERTAINTY.  or this RA is not worth the paper it is made on.

Read the Methanol MSDS sheet.

Educate the work crew about the dangers .

Methanol is a non static generator and you can use a barrel pump at good pressure if required.

The workforce must be proficient in wearing AIRLINE sets-- here the pressures are monitored from outside tank.

Methanol spray must be done only in daylight hours as far as practicable.

The sprayer must wear full chemical resistant gas suit not oilskins.

Outside the tank SCBA set and harness/ line must be available for rescue .

Methanol should be sprayed only after the entire cleaning operation is over as the final polish up act—or the whole thing is wasted.

Test the methanol drum for chlorides. UCC wants 0.249 PPM chlorides for MEG FG .

Run a PTT test on the drum methanol and check if it holds at least one hour.

Usually Methanol spray is done with a dedicated barrel pump.

Flush the pump and hose with DI water before and after use.

Initial Methanol spray-- waste it into the sump to flush out line contents.

Methanol will extract chlorides, HC , and colour if it came from steam ( not from previous cargoes ) from the bulkhead.

If chlorides are your only problem use DI water.

Prior to spraying place a M2 wilden pump in tank impeller sump to eject it from the tank. This will reduce the gas freeing time and reduce the methanol mist inside the tank.

Give 2 runs.

It is best done by one sprayer following the other.

The leading dirty edge must be washed to the bottom . If it dries up half way on the bulkead it can be seen visually.

Spray from ford to aft and top to bottom.  use a wilden pump at the sump , to pump out methanol --to reduce the gas in the tank.

Gas feeing after the job is best done while running steam coils.

The muck brought down to the bottom must be removed with sponges and DI water.

Check the gas content using Draeger tubes. Bring it down to 50% of TLV.

Do wall wash .

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Generally sonsidered as a universal solvent, because it is aggressive towards HC and substances not soluble in water, being completely soluble in water itself. Methanol is intoxicating but not directly poisonous.

Colourless
Watery liquid
Alcohol odour when pure
Flammable
Toxic vapors at room temp.
Ingestion/ ihalation poisoning can cause dizziness, unconsciousness , blindness ( if drunk ) and sighing respiration
Check for chlorides when you receive the drums. Must have cert for PTT> 60 min
Non static generator
Cat Y
USCG/ 20
VP 92 mm hg at 20C
BP/ 64C
FP/ 12C
VD/ 1.1
Completely soluble in water—due to ionic bonding
Steaming—9 litres on 100 cum to ensure LEL is not exceeded
TLV 200 ppm
AIT/ 464C
ST/ 22.6 dynes / cm at 20C


Remarks:
Methanol shelf life must be monitored—test the methanol before use—lest it fails a clean tank.

It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odor .

A Methanol flame is almost colorless. Methanol is intoxicating but not directly poisonous. It is toxic by its breakdown (toxication) by the enzyme Alcohol Dehydrogenase in the liver by forming Formic acid and Formaldehyde which cause blindness by destruction of the optic nerve.

Though it is miscible with water, Methanol is very hard to wash off the skin; it is best to treat Methanol like gasoline.

The initial symptoms of Methanol intoxication are those of central nervous system depression: headache, dizziness, nausea, lack of coordination, confusion, drowsiness, and with suffiently large doses, unconsciousness and death. Once the initial symptoms have passed, a second set of symptoms arises 10–30 hours after the initial exposure to Methanol: blurring or complete loss of vision, together with acidosis. These symptoms result from the accumulation of toxic levels of Formate in the bloodstream, and may progress to death by respiratory failure.

Ethanol is sometimes denatured (adulterated), and thus made undrinkable, by the addition of methanol. The result is known as methylated spirit.

Unlike petroleum fires, Methanol fires can be extinguished with plain water (while Methanol is less dense than water, they are miscible, and the addition of water will cause the fire to use its heat to boil the water).

REMEMBER- METHANOL CANNOT DISSOLVE SALT.


-------CAPT AJIT VADAKAYIL ( 29 years in command )

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