Procedure-
After a prolonged hotwash allow the tank to rest prior doing wwt.
Go to tank and collect 200cc of wash in a clear bottle. To achieve this you must squirt at least 500 cc from a polyethylene squirter to allow for spillage. Never miss the leading edge of dirty wash flowing down the wall. Make your own funnel by slicing off a Polyethelene bottle with an extremely sharp box cutter blade. Mate it on a porthole glass pour methanol and see it does not spill even a drop. The neck of this funnel must lead direct into the sample bottle ( narrow neck ). With a gloved hand you must be able to hold both, the other hand for the squirter.When you dispose wash Methanol in CCR sink run the water tap as a safety measure lest it gasses up a sleeping seaman in a cabin.
Always use same pipette for each lab ingredient, do not change. Wash funnel after each use inside the tank—make SURE. Use parasol to prevent salt spray ingress into tank.

HC test:
25cc wash plus 75 cc distilled water in a stoppered tube. Shake vigorously and stand. Come back after 20 minutes and if there is foam layer on top test has failed. To pass it must look like distilled water. For places like Kuwait the HC test is so strict that it is better to use 1:1 ratio. If you shine a torch beam from the side it must not look blue.
Ashore they qualitatively filter the wash using 5A filter paper or Whatman 42 after leaching the paper with Methanol to remove industrial paper chlorides.

Chloride test:
50cc un-filtered wash add to 30 cc distilled water shake well to dissolve salt and then filter qualitatively.
Colloidal particles are not simple molecules but physical aggregation of molecules . They readily pass through ordinary filter paper.. Turbidity is a measure of the refraction of the liquid. Colloidal matter indicates hydrocarbons, chlorides and other residues.

Note: Methanol cannot dissolve salt or loosen the sodium cation/chloride anion from the NaCL ionic bond. -only water with high solvent power and high dielectric constant can do this. NaCL crystal is extremely strong and rigid. A Sodium ion is equally attracted to 6 Chloride ions.
To this 80cc mixture--- add 1/2 cc silver nitrate( strength 10%) plus 2cc nitric acid ( strength 20%) plus 17.5 cc di water to make 100 cc total.
Shake and stand for 5 minutes. Compare milkiness with a standard comparator of 1ppm made as follows:
50cc Methanol + 4cc standard Chloride soln ( strength 10ppm ) + 1/2 cc Silver Nitrate ( strength 10%) + 2cc Nitric acid ( strength 20%) + 43.5 cc DI water to make total 100cc solution . Memorise this milkiness as the failing standard for the current voyage.
(for 0.5 ppm comparator put 2 cc of standard chloride soln, for 0.250 ppm put 1 CC.) For 2 ppm put 8cc NaCl ----for 4ppm put 16cc NaCl.

Why Nitric acid ??--- Nitric acid parts the silver vide the assaying process as chemically silver is not active and dissolves only in strong Nitric acid or H2So4.
The method of not involving Nitric acid in the Chloride test could pass a ship staff tank WWT , while a shore gas ion chromatograph will fail the sample for Mono Ethylene Glycol fibre grade. Nitric acid decomposes Sodium Cyanide and Sodium Sulphide which otherwise form precipitate with AgNO3 and thus interfere with the lab test.

KMNO4 PTT test---
It is easy to fail this test if gasolene dye fillers / cutters or inhibitor chemical is present.
Hydrocarbons do not react with KMNO4.
50cc filtered wash + 2cc KMNO4 ( 0.02 % strength ). Mix 0.1 gms of the solid in tube to 500 cc of di water to get 0.02% strength. It takes 1.5 hrs for the KMNO4 crystals to dissolve. The pot life is only 3 days so keep it in the fridge in a amber coloured bottle. Keep in a dark place at 15C.Note the time taken for the purple pink colour to change to straw yellow .Must hold for 50 minutes in the bath of 15C in a dark place. Check every 5 minutes.

Use HCL, then DI water, then Methanol to wash glass , then water and finally Methanol. Under the purest conditions KMNO4 test will run 120 min. If the bath is colder than 15C the test will run longer.
For PTT 50 min at 15 deg C = 30 min at 20 deg C= 20 min at 28 deg C.
Do PTT tests for all tanks at same time—this way you know which tank is the best/ worst.

Notes---
1) Use new latex surgical gloves for each tank. Wash gloves in tank after wearing with Methanol. Use different droppers pipettes for different reagents.
2) No smoking in CCR when the lab test is going on.
3) Write down results immediately
4) Some types of plastics release hydrocarbons. So better use glass bottles.
5) Surveyors methanol should be 0.100 ppm.
6) If PTT test fails you must witness a retest using freshly prepared ships KMNO4 solution.

Strengths:
For 20% HNO3 add 20ml conc HNO3 to 80 ml water.
For 10% AGNO3 dissolve 100 gms of reagent grade AGNO3 in 900 ml water.
For NaCL 10ppm dissolve 10 mg NaCL in 1 litre water.
For KmNO4 0.02% dissolve 0.1 grams crystals in 500 CC water.

We will need to update operator and charterers daily with numbers of WWT. As long as the results get better-- ship cannot go offhire in a court of law.

Reporting to office by email : Code for HC CL and PTT
Tank identity
HC/ scale of nil/ low/ med/ high
CL/ ppm 0.249 to 15 ppm.
PTT/ 50 min at 29 deg C

Compare this with Methanol requirements . You will realise Methanol standard is very low when compared to MEG fibre grade.
Cl/ 2.0
Colour/ 15 Apha.
Suspended matter/ not so stringent
Odour/ allowed
Moisture/ Methanol does not absorb oxygen and moisture.

When you copious spray methanol in a tank first ensure the bulk methanol has less than 1 ppm chlorides and shelf life is <3>
In my experience I have measured 1.5 ppm chlorides in Methanol of 200 litre drums.
Keep Draeger tube for methanol ready. Bring ppm to <80>

Be happy in your work. Only then you can pass the WWT and first foot.

This reagent procedure is so exact that all your readings taken by different people should be the same. After all you are just comparing with a standard solution.



Remember that wall wash test is all about comparing ( holding side by side) the washed unknown solution with a standard known solution---
This is to eliminate
1) contaminated
2) expired
3) unknown strength
--reagents from interfering with your results.

So first you must make standard solutions using pure distilled water and pure lab methanol and memorise its milkiness. Later when you have more experience you need not do this , --- then only it will be a true ‘ on the spot’ roving test.
Have in your boiler suit pocket 2 squirters. One with pure lab methanol and other with distilled lab water. Also have 2 test tubes marked for 20CC.
No filtration is done .
Fast test chlorides:
Take 10 CC methanol wash and 10 CC distilled water. Put one drop of Silver Nitrate (10%). Shake with a stirring gentle motion and compare milkiness with memory in a dark place .

Once in a while test---
Tankcleaning fresh water (fresh water quality )
Amberlite filter discharge ( DI water quality )
Condensate water from steam inlet main pipe ( steam quality)
Bulk methanol from 200 litre drum ( methanol shelf life ). Never use the bottom 2 inches in drum.

Fast test hydrocarbons:
Take 5cc Methanol wash and add 15 CC distilled water, shake vigorously and see the time taken for bubbles to disappear. It should disappear in 30 sec and then look like distilled water. Make sure the tank surface is dry.
This roving test is only for “intermediate on the spot tests” by chief officer , and should not be used as a substitute for final test.
Wash flowing down bulkhead must be collected at the leading dirtiest edge by dragging the funnel down.

Miscellaneous tests:
If the nest cargo is wall wash make sure you use good salt water for washing. Don’t wash with muddy water and spoil your tank when washing near the coast or at mouths of rivers and harbours. In many seas you find cargoes like molasses and palm oils in substantial quantities.
To test sea water for plankton mix 75 ml water with 25 ml Acetone . If plankton is present they will settle down at the bottom.

Acid wash test for BTX: to check for contamination of aromatics by oil. Or to determine if petroleum hc are present in aromatic compounds.
To test cleanliness of tank dip cotton in toluene and wipe one sq metre of bulkhead. Wring out the toluene to test.
7 cc Sulphuric acid + 21 ml Toluene wash shake 100 times and stand for 10 min . Should be clear if no oils or fats are present. Color of acid at the bottom of the tube is compared with standard shades

NaOH fatty acid test:
The quantity of fatty acid in veg or animal oils is a measure of the quality of oil or the degradation which occurred during transport. The sample is first dissolved in alcohol and afterwards neutralised with NaOH. The quantity of NaOH required is a direct indication of the acidity of the oil. You can use ph value paper to detect the change or do a titration with coloured lab reagent phenophtelein—to indicate the change from acid to neutral ( end point of titration ) to alkali.
Even if miniscule amount of previous cargo is seen visually , never conduct WWT or never start to remove hydrocarbons by methanol spray or to improve PTT. Don’t spend costly chemicals and time in vain.
                         
                          Chemical Grade Methanol
Lab methanol must have minimum specs as follows-
Permanganate Fade Time (Min) - 100 minimum
Chloride, as cl (ppm wt) - 0.05 maximum +
Colour (APHA) - 1 maximum
Hydrocarbon test - PASS
Residual odour * - NIL
(*) Residual odour is determined by evaporating 100 ml of methanol on a 10 cm filter paper. The paper, when just dry, is tested for any odour. None should be detected. It is permitted to use a fan blower to assist evaporation.


WALL WASH EQUIPMENT                                 
      ( to be ordered from dedicated wall wash lab store )

1) Reagent Silver Nitrate—strength 10% /  250 cc –2 Bottles
2) Reagent Nitric acid --- strength 20% / 500 cc- 2 bottles
3) Reagent Potassium Permanganate crystals – 0.1 gms in stoppered tubes/ 12 tubes
    for making 0.02% solution on the spot.
4) Reagent Standard chloride solution ---strength 10 ppm/ 500cc—2 bottles
5) 5 Apha, 10 Apha, 15 Apha--Standard comparator solution in stoppered tubes
6) pH value paper colour comparator strips 1 to 14—4 boxes
7) Nessler tube with round bottom 100 CC  and white markings / 16 nos
8) Stand for above tubes
9) Nessler tube with flat bottom stand 50 CC/  24 nos
10) Polyethylene methanol wall wash squirt bottles 500 cc/ 4 nos
11) Polyethylene wall wash funnel with flat side and 60 deg angle short stem/ 4 nos
12) Pipette glass pyrex brand 5 CC/ 4 nos ( graduated)
13) Pipette glass pryes brand 10 cc/ 4 nos  ( graduated )
14) Conc Hydrochloric acid/ 500 CC
15) Lab grade methanol  chlorides < 0.05 ppm / 60 litres
16)  DI water/ 60 litres
17) Thermometer 0 to 100 deg C/ 3 nos
18) Ice box portable with white interior to hold at least 12 nessler 100 CC tubes vertically
19) Sample bottles wide mouth transparent glass 500 CC/12 nos
20) Wall wash plastic bucket/ 2 nos
21) Parasol wide 2 metres dia/2 nos
22) Washing brush for nessler tube/ 2 nos
23) Penlite torch / 2 nos
24) Disposable vinyl gloves/ 100 nos
25) Disposable shoe covers plastic—lint free / 100 nos
26) Filter paper 5A and Whatman 42# 10 cm paper filter qualitative, white / 100 nos each
27) Palladium chloride solution/ 50 cc
28) Disposable 5CC pipettes—100 nos
29) Lab grade acetone ( for NVM and Plankton of sea water )— 20 litres
30) Stainless steel funnel / 2 nos
31) Sponges for Lint free mopping and wiping steam coil bottoms.
32) Methanol Draeger tubes  50ppm –3000 ppm range / 50 nos ( expiry dates to note )