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Articles or papers related to tank cleaning operations

MARPOL Annex II – Category X Products – Exemption from a Pre-Wash

MARPOL Annex II – Category X Products – Exemption from a Pre-Wash

MARPOL states that after discharging, all tanks must be pre-washed and the resulting residues discharged to a reception facility: – Regulation 16 4 A tank which has carried a Category X substance shall be prewashed in accordance with regulation 13.6. The appropriate entries of these operations shall be made in the Cargo Record Book and endorsed by the surveyor referred to under paragraph 1 of this regulation. However, there are still ports where an approved MARPOL surveyor is not available…

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Dye Discolouration

Dye Discolouration

Dye discolouration caused by the carriage of dyed gasoline (for example) can be removed by recirculation washing with a Sodium Hypochlorite (Bleach) Solution. Sodium Hypochlorite is normally supplied as a 12% solution. Make a 2% solution of this supplied 12% solution in water (freshwater preferred, otherwise seawater) and recirculation wash at a maximum temperature of 40 deg C. 2% of a supplied 12% solution is 200 liters in 10,000 liters of water.

PTT (Improving Test Results)

PTT (Improving Test Results)

Oxidized residues of previous cargoes can cause a failure of the PTT. To improve the results, wash with a Sodium Hypochlorite Solution (Bleach) in freshwater. Sodium Hypochlorite is normally supplied as a 12% solution. Make a 2% solution of this supplied 12% solution in water (freshwater preferred, otherwise seawater) and recirculation wash at a maximum temperature of 40 deg C. 2% of a supplied 12% solution is 200 liters in 10,000 liters of water. Also used to remove red/yellow dye…

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Sodium Hydroxide (Caustic Soda Solution) – Cleaning with

Sodium Hydroxide (Caustic Soda Solution) – Cleaning with

Sodium Hydroxide may react with the calcium and magnesium in seawater during tank cleaning operations to form calcium and magnesium hydrates which shows as white powdery deposits left on the cargo tank surfaces, especially when using hot water washing. A freshwater rinse following a caustic recirculation wash prior to the final seawater wash will assist in the prevention of such deposits. Such deposits may be removed by washing with an acid-based cleaner. Washing with a Potassium Hydroxide Solution instead of…

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Typical Recommended Testing for 1st Foots

Typical Recommended Testing for 1st Foots

The Chart below serves as an indication of the typical tests that may be expected on the 1st Foot Samples based on the previous cargo history. These typical tests are an indication only, and may vary according to Terminal Requirements. This Chart may be downloaded as a pdf document here: Recommended Tests for 1st Foots

Chlorides: Organic vs Inorganic

Chlorides: Organic vs Inorganic

Organic vs Inorganic……..what’s the difference? There are a multitude of publications which refer to ‘Organic’ or ‘Inorganic’ Chlorides, with ‘Organic’ Chlorides being an undesired contamination. But which is which and what products contain which element? The following is an attempt to explain this. Organic Chlorides are an undesired contamination in crude oils. The presence of even a very small amount (a few ppm) of chlorides can be catastrophic during crude oil fractionation in the refineries which can cause considerable damage…

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Wall Wash Test Precautions and Causes of WWT Failures

Wall Wash Test Precautions and Causes of WWT Failures

Wall-Wash Test Precautions and some Causes of Failure Always use disposable plastic gloves when wall washing – the human hand contains more salt than normal requirements and is a common cause of chloride contamination. Wear clean clothes and do not allow working gloves in the tank, avoid all contact of clothing with the tank, wear protective disposable shoe covers. Use a clean bucket on a clean line for transferring test equipment into the tank. Wash the funnel and sample bottles…

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Water White to Water White

Water White to Water White

A simple powerpoint presentation detailing a chemical tanker’s progress from a water-white condition back to a water-white condition. May be used to demonstrate to new officers and crew the progression of a cargo from receiving loading orders to the final return of a tank to a water-white condition. It may also be used for the same reason, but to shore-based personnel.

Water-White Standard

Water-White Standard

Returning a cargo tank back to a water-white standard is, or should be, the default tank cleaning operation following the discharge of any product on a chemical tanker. From that default position and depending on the next product to be loaded, additional cleaning can take place to suit the supplied product specifications. Should the specifications of the next product not have been advised, then cleaning should be carried out to the highest known specification for that particular product. Of course,…

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