Wall Wash Test is a method for collecting and analysing wall wash samples to determine the presence of contaminants on the bulkheads. The procedure involves contacting a constant area of the bulkhead with a given amount of specification grade methanol, collecting the liquid and analysing it for the presence of chlorides, hydrocarbons, colour and particulate matter, whatever might be required by the charterer.

Wall Wash Procedure

PRECAUTIONS

Safety Considerations – eye protection is required when collecting the samples to prevent the inadvertent contact of methanol with the eyes during the sample collection process. Gloves should be worn to prevent the absorption of methanol into the skin.
Disposable plastic gloves are also worn to prevent contamination of the samples during the collection process. (A sufficient amount of chlorides can be absorbed from the skin to cause the sample to fail the chloride analysis.)
Chlorides are abundant in the marine environment. All sampling equipment including bottles, funnels and other apparatus must be thoroughly rinsed with methanol (of less than 0.2 ppm chlorides content) and stored in plastic containers. Bottles are to be capped prior to sample collection.
Personnel collecting the samples must be certain that no perspiration or bare skin contacts the sample or sampling equipment while the wall washes are being collected.

CHOICE OF TEST SITES

As a minimum, four sites of approximately 1.2 square feet each must be chosen in each tank. (If additional sites are chosen, 100mls of methanol should be applied to each location and collected in a separate container.)
Any area that appears to have crystalline deposits should definitely be tested. A separate test of non-typical areas greater than 2 square feet (discoloured patches etc.) should be conducted. The sample collected should be labelled with a description of the non-typical area. (These areas should be analysed separately.)

SAMPLE COLLECTION PROCEDURES

Choose four surfaces to test.
Using the plastic wash bottle, squirt methanol on the test section at the highest practical point (normally 1.5 up to 2 metres) above the tank bottom in a stream of about 10cm wide.
Allow the methanol to run down the wall approximately 15 cm and begin collecting it with the funnel, squirting additional liquid as necessary to rinse the flushing into the sample funnel. Continue this process until approximately an area of 10 by 120 cm has been rinsed with 100 mls of methanol.
After the washings from the four sites are collected, submit a portion of the sample for analysis of chlorides, colour, suspended matter and hydrocarbons, whatever is applicable.
The accuracy of this test depends upon consistency.

• Consistent number of sites tested.
• Consistent area tested at each site.
• Consistent amount of methanol applied to each site.
• Consistent amount of methanol recovered from each site.

Wall Wash test kit