Methanol (99.99%) WWT Kit - 2.5 Ltrs Glass Bottle

This text contains is a typical procedure used on one of my previous ships to convert from high brix (93) Columbian Molasses to MEG fibre grade for UCC.



Olefins, Pthalates, Adipates, Fatty acids and Fatty alcohols are bad previous cargoes for next wall wash cargoes.



Wall wash test for Mono Ethylene Glycol fibre grade is the most stringent.



When you take a wall wash ensure the tank is perfectly dry ( especially zinc coated tanks ). There can be no sea spray as WWT is a weather permitting procedure especially for MEG (fg) where chlorides fail for union carbide corporation at 0.249 ppm. Tell master to alter course during ventilation and wall wash. FW rinse area around tank entrance to remove salt from sticking to shoe cover. Suspect like a paranoid moron that every thing that the methanol comes in contact with , till you write down the results could be dirty . Do not be stingy with lab methanol. Ensure your sweat drop does not alter results.



Wallwash is taken from 4 parts of all 4 bulkheads—but not from corners,which do not count as a standard value. Surveyors must be accompanied inside tanks by a responsible person.



For Wall Wash take into the tank one litre of Methanol. Only 200 cc 1/5 of this amount is brought out for testing. After filling up squirt bottle with methanol, analyse for HC and CL first before taking into the tank.



WWT surveyor must not wash more than 6 feet height. He also cannot wash the bottom unless you are loading Hexene 1/ potable Ethanol etc.. Floor areas are tested by placing ( not wiping ) filter paper on a spot wetted by Methanol. This paper is placed inside a sample bottle and 50 cc test Methanol is added for every piece of filter paper. If any surveyor wipes bulkheads with Methanol soaked instead of squirting Methanol using a polyethylene squirter , tell the master as this is not a representative sample of the action of liquid on the bulkhead .



Methanol spray by crew to beat the surveyor is not a bright deed in the context of MEG FG as all you do is to bring the dirt from sides to bottom. So mop bottom sides with sponges and DI water. No rags are allowed as more than 10 suspended particles in the first foot sample fails for MEG FG. Use torch beam at zero incidence in a dark tank to detect lint shed from paper shoe covers.



Various tests done all over the world are---- (remember all of them may not be applicable to your cargo, so find out well in time. The main ones are HC, CL and PTT. )



1)Visual first impression

No condensation moisture on cold interface bulkheads or deck head,no blistered or open splits on epoxy coating, no white coloured patches of Zinc salts or Calcium and Magnesium sea water salts , no black rouge Fe3O4 tattoed into stainless steel active surfaces from oxidised welds, no red Fe(OH)3 due to boiler water alkaline additives etc, no green vitriol Ferrous Sulphate patched on stainless steel active areas. Use Bufferclean Citric acid of pH 5.5 to remove salts from zinc tanks and adsorbed ( this is a surface phenomenon in zinc tanks and is different from absorbed ) previous cargo reactant matter. Dye out is an organic stain remover.



2)Odour of tank

Meg is odour absorbing . Use lac to remove odour in SS tanks. Acrylates have their own smell killers like Monoethanolamine and air fresheners marketed by tankcleaning chemical companies. After a strong smell cargo if the next cargo is odor sensitive the seals of tank dome / butterworth ports may have to be exchanged. Pyridine cargoes give very strong odour.



3) Colour of Methanol wash

Colour 5 Apha (or Saybolt ASTM D12095) is required for the MEG fg wash ( highest spec.) . Must see in day light or fluorescent light against a white sheet of paper at night. Use the magnifying glass or even your reading glasses



Apha solution is platinum chloride solution. The number of cc Apha solution ( min is 5 cc ) for Apha 5 added to distilled water gives the shade number.



Lightest is +30 Saybolt and darkest is -16 used only in the petroleum industry. Water White standard colour is in the range of +30 to +20.



Apha zero means clear. In your wall wash lab you must have comparator nessler tube ready made solutions of A5 A10 and A20 ( always in multiples of 5 ).



The standard apha solutions are stable for many days but should be done again after one week. The stock solution is stable for an indefinite period if kept in a refrigerator.



Proforma: ml of 500 APHA Stock Solution Diluted to 100 ml with Distilled Water/ APHA number

1/5

2/10

3/15

4/20

Slightest colour in previous cargo can cause untold problems with wall wash of zinc tank. Don’t allow dyed CPP unless you are looking for big trouble. However dye out bleach can be used to remove dye of gasolenes.



4)Suspended matter in wash:

Check in a dark room , against black background. Shine thin beam torch from bottom of a round bottom tube . MEG fg WWT fails with a single suspended particle. For first foot it is ten. Particulate matter which sink to the bottom is not a cause of failure for MEG fg.



Remember colloidal particles readily pass through ordinary filter papers. Animal membranes can hold them.

The path of light through a colloidal suspension is called a Tyndall cone.



Filter papers are made of particular pore size by impregnating ordinary filter paper with colloidal particles. Colloids may be coloured or transcluscent due to Tyndall effect. Tyndall effect is the scattering of light by particles in the colloid.



5) Chlorides


UCC wants 0.249 ppm for pass. Black back ground check with torch from under. Ashore done by gas ion chromatographs. Lab methanol is tested to 0.100 ppm chloride by ion chromatography. Method used for separating dissolved substances by partition or aDsorbsion is called chromatography.



Photospectrometer and conductivity meter can be used on board. The Whatman #42 filter paper used prior chloride test is chloride free and ashless. If you don’t have a good filter paper leach it with lab methanol.

Glycols, Methanol and Ethanol are very sensitive to contamination by chlorides.

It is MOST important to run both wash samples and standards solutions simultaneously and view them together as the silver chloride turbidity produced continues to undergo a photochemical reaction.

Use pipette bulb, do not pipette by mouth.



6) Hydrocarbons

Found out by looking for time taken for bubbles to disappear or foam on top. Now this foam could be old Genepol extracted from pores by methanol in a zinc tank. If previous cargo is insoluble in water HC WWT may fail. So use HC free cleaner to pass the HC test.. This test can be called water mixibility test. Can be shaken 1:4 (not strict ) or 1: 2 ( very strict ). In Kuwait they overdo it and do 1:1.



When a light beam is used it is called Tyndal test. Methanol is very sensitive to oil contaminants. Light beam is deviated by HC contaminants . Turbidity ( milky emulsion )is a measure of refraction of the liquid. No beam means HC free. Faint white beam means 1 ppm HC. Blue beam means excess of 2 ppm. Remember blue colour of sky is due to the scattering of light by colloidal particles of dust in the air and not due to HC.

Methanol is very sensitive to oil contaminants.

Celanese report HC as ppm n-Heptane. They make various standard solutions by mixing n-Heptane with Methanol and water.

Some rubber and plastic release HC. So only approved equipment should be used.



In many ports the HC test is pass or fail, no attempt is made to estimate quantity of hydrocarbons as the turbidity produced depends on the actual hydrocarbon . This is because certain chemicals like L A B (linear alkyl benzene) give turbid solutions at very low ppm concentration whereas Toluene and other aromatics require extremely high concentrations before it can be detected .

After a failed WWT it is good practise to rinse the tube several times with water/lab methanol with the use of a bristle brush.



7) PTT

Look down into tube kept in a cold 15C water bath of white colour in daylight or fluorescent tube light. Low PTT is often the result of a reducer remaining on the tank surface which could be the cargo itself.Bleach is known to be contrary to a reducer and is an oxidising agent. Recirc at 50 deg after opening the pores of the coating. Wash old PTT tested glass in HCL, then water and then Methanol. The pinkish purple of the Potassium Permanganate solution changes to straw yellow ( Manganese di Oxide ). Extreme of pH can interfere with test. Check every 5 minutes . PTT test detects all inhibited chemicals. Make new KMNO4 solution every 3 days and store in an amber coloured bottle.Under purest condition PTT test will run for 120 minutes. PTT test fails only when contaminants react with KMNO4. HC does not react with KMNO4. So PTT time can be increased by Bleach or Chlorinated solvents . An equivalent of Stolt X is marketed by chemical companies too to neutralise the effects of Acrylic Monomers.



To get the true color of the faded straw yellow a standard solution of platinum cobalt (Uranyl Nitrate ) is available in the market.



The Potassium permanganate solution should be stored in brown bottles and in the dark.

Even if the PTT test taken on board before arrival passed, gives no quarantee to have the same result from the surveyors test. (Different spots taken by surveyor).



Glass apparatus that have a `brown film' should not be used as it is Manganese di-oxide, the reduced product of potassium permanganate. This will catalyse the oxidation/reduction decolorisation process of potassium permanganate and will give less PTT time. Glassware is cleaned by overnight immersion in an acid bath of 50% hydrochloric acid. The clean tubes must then rinsed well in tap water followed by DI water / Methanol.



Similarly, the flask containing stock solution of potassium permanganate requires cleaning between batches of fresh solution. The last rinse should be with fresh potassium permanganate solution and not methanol.

Glass apparatus that have a `brown film' should not be used as it is Manganese di-oxide, the reduced product of potassium permanganate. This will catalyse the oxidation/reduction decolorisation process of potassium permanganate and will give less PTT time. Glassware is cleaned by overnight immersion in an acid bath of 50% hydrochloric acid. The clean tubes must then rinsed well in tap water followed by DI water / Methanol.

Similarly, the flask containing stock solution of potassium permanganate requires cleaning between batches of fresh solution. The last rinse should be with fresh potassium permanganate solution and not methanol.

Uranyl nitrate is HIGHLY TOXIC. This substance must not come into contact with the skin and NEVER be pipetted by mouth. Treat the Uranyl nitrate/ Cobaltous chloride standard solution with care.



8) NVM :

To determine the weight of residue left on the surface. Spray Acetone / Hexane on a small area. If sprayed area has a visible boundary ( bur n marks ), non volatile matter is there. NVM consists of high BP sediments, dirt, rust etc.

Ashore it is done by evaporating the Methanol wash and weighing.



9) pH:

Ph value greater than 9 ( boiler alkaline additive ) in the pipelines will cause the MEG fg deslopping contents to take the tinge of Venetian red. For certain cargoes like Phenol the pH test is check for acidity.



10)COD test: chemical oxygen demand test. The impurities are extracted by methanol and analysed with an oxidiser like Pot Dichromate.