Chemical Tankers / Day 3 / Day 3 Topic 6 Tank Cleaning Chemicals & Best Industry Practi

6.1 Tank cleaning chemicals

Alkaline cleaners or saponificators

Alkaline tank cleaners are using in cleaning after animal and vegetable products such as drying, semi-drying oils and non-drying natural oils. For example: Unitor’s Alkleen Liquid is a heavy duty water based alkaline tank cleaner, containing natural base detergent including caustic soda.

6.1 Tank cleaning chemicals

Alkaline cleaners or saponificators

Saponification is basically a process which turns the residue into a soapy solution. This type of cleaning is ideal for animal, fish and vegetable oils and fats as they are esters and are composed of glycerol and fatty acids which can be broken down by an alkaline such as caustic soda.

6.1 Tank cleaning chemicals

Alkaline cleaners or saponificators

The fatty acids react with caustic forming a soapy mixture which is soluble in water and thus simply washed away.The soapy mixture will act as an emulsifier and further enhance the cleaning process.

In certain cases it is necessary to combine the cleaning actions of the Emulsifier and Saponifier to achieve the best results.

6.1 Tank cleaning chemicals

Acid based cleaners

Acid based cleaners are mostly used as rust removers and white powder spots (after initial animal or vegetable oil cleaning) removers. For example: Unitor’s Metal Brite H.D. is a liquid detergent compound containing phosphoric acid and non-ironic surfactants used for rust removal and as a surface brightener.

6.1 Tank cleaning chemicals

Solvents

All solvents may be divided into two categories: those being soluble in the water and those being insoluble in the water.

Water and salt water are also a solvents. Certain important organic solvents are: white spirits, chlorinated solvents, toluene, methanol and acetone.

6.1 Tank cleaning chemicals

Solvents

The number of organic solvents is vast. Most of them are using in final stages of tank cleaning process when a hydrocarbon or chloride removal is required.

6.2 Cleaning chemicals compatibility with tank coatings

The manufacturer’s tank coating resistance list should always

be consulted prior to use of any cleaning chemical agent.

6.2 Cleaning chemicals compatibility with tank coatings

The following cleaning chemicals might be used during tank cleaning preparation bearing in mind their compatibility with coatings:

• Chlorinated solvents (Trichloroethylene, Perchloroethylene, MEC, MCB)

-in stainless steel and zinc coated tanks. Epoxy coated tanks depend upon the coating resistance;

6.2 Cleaning chemicals compatibility with tank coatings

•Emulsifying agents and grease removers – in stainless steel, epoxy, zinc and phenolic coated tanks;

•Alkaline Cleaners – in stainless steel, epoxy and phenolic coated tanks. For zinc coated tanks, a caustic substitute cleaning chemical should be used (for example: Alkeen Safety Liquid);

6.2 Cleaning chemicals compatibility with tank coatings

•Acid based cleaners or Metal Bright – in stainless steel, epoxy and phenolic coated tanks;

•Butyl Cellosolve (solvent) – in stainless steel, zinc and epoxy coated tanks;

•Methanol – in stainless steel, zinc, epoxy and phenolic coated tanks;

•MEK or Acetone – in stainless steel, zinc, epoxy and phenolic coated tanks;