Chemical Tankers / Day 4 / Day 4 Topic 8 Tank Coating & Resistance List
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Absorption /desorption of cargo
Absorption of a substance into a paint film proceeds at an initially rapid (linear) rate and then falls to zero when the film becomes saturated.
Tank coating
It can be seen from previous slide, the quantity of absorbed
cargo rapidly reaches a maximum within three days but thereafter stays approximately at that level for the duration of the laden passage. Following discharge (day 14) desorption occurs at a rapid rate until after four days there is no significant further loss of the retained species.
Tank coating
Cargoes with small molecular structures area are able to penetrate organic coatings to a greater extent than those cargoes with larger molecules, thus methanol is known to be a very penetrative cargo and is widely acknowledged within the industry as being one of the most " aggressive" cargoes that can be carried in organic coated tanks. Absorption/desorption characteristics for each cargo will differ.
Resistance of Tank Coating
WHAT IS THE `RESISTANCE LIST' ?
DISCUSS
Resistance of Tank Coating
The suitability of a tank's coating for the carriage of a particular substance can be investigated by referring to the `RESISTANCE LIST' that is issued for a particular material/coating. The resistance list is normally issued by the coating manufacturer and is indicated by a "Noxious Liquid Substances" certificate, which states the cargoes that can be carried. You enter into the "Resistance List' with the name of substance. The outputs from the `Resistance List' may have a number of different meanings as follows:
Resistance of Tank Coating
"RC" |
= |
Resistance code |
"+" |
= |
Suitable |
"-" |
= |
Unsuitable |
"RC" +1, 2, 3, etc |
|
= Suitable, subject to reference notes 1, |
|
|
2, 3, etc. |
RC +T (ºC) |
Suitable up to T degrees centigrade. |
The `Resistance List' and any temperature limitations of the tank coating must be followed. Maximum temperatures must not be exceeded as damage to the tank coating will occur.
Certificate of Fitness
As per IBC Code, any cargo offered for bulk shipment shall be indicated in the shipping documents by the product name by which it is listed in chapters 17 or 18 of the Code or the latest edition of MEPC.2/Circ. (Tripartite Agreement) or under which it has been previously assessed.
Certificate of Fitness
Ship’s Fitness List
Certificate of Fitness
Footnotes for cargo to
be loaded should always be consulted before loading and strictly followed.