Risk of cargo contamination during loading at chemical tankers
Handling noxious liquid chemicals in bulk got numerous difficulties.
Outlined below are some problems associated
with various cargo systems found in tankers.
There is a high risk of contamination when a
common pump is used for several chemical tanks,
if the system is not properly drained between
different cargoes.
Modern tankers are often equipped with individual submersible cargo pumps but if these are connected to common or shared lines there is still a risk of contamination.
There will normally be a drain cock near or on the cargo pump itself, this drain cock should be opened to verify that the line has been properly drained before pumping a different cargo. In addition most of these pumps are hydraulically driven, damage oil seals can lead to hydraulic oil leakage into the cargo tank contaminating sensitive cargoes.
Modern tankers are often equipped with individual submersible cargo pumps but if these are connected to common or shared lines there is still a risk of contamination.
There will normally be a drain cock near or on the cargo pump itself, this drain cock should be opened to verify that the line has been properly drained before pumping a different cargo. In addition most of these pumps are hydraulically driven, damage oil seals can lead to hydraulic oil leakage into the cargo tank contaminating sensitive cargoes.
On oil tankers it is normal to have a common cargo tank ventilation system. The
vapours from one cargo tanks can easily enter a different tank in the system. This may
result in cargo contamination or change the flash point of the product. Petroleum
products are classified into volatile and non-volatile cargoes. A cargo with a flash
point below 60°C is a volatile product and a cargo with a flash point above 60°C is a
non-volatile cargo (different rules apply to the handling of volatile and non-volatile
cargoes).
Diesel oil has a flash point of around 63°C and vapours from a volatile cargo can easily change the flash point to below 60°C, causing the cargo to be re-classified. Many lube oils and lube additives are heated during transport. Steam coils are normally used for this purpose. A leaking heating coil can lead to water entering the cargo tank and consequently contaminating the cargo. Laboratory tests should be carried out on cargoes contaminated by water. It should be established whether the water is fresh or salt water. Contamination caused by fresh water is most likely to be caused by a leaking heating coil whereas salt water contamination would probably be caused by a leaking tank hatch, in which case the hatch packing should be checked.
Chemical tankers are normally constructed with completely independent cargo systems. Each cargo tank will have an independent pumping and venting system.
Cargo contamination in chemical tankers are often caused by poor cleaning of cargo tanks or pipe lines. Unfortunately many chemicals are extremely sensitive to contamination, just a few parts per million of a previous cargo can contaminate an entire shipment.
Many cargo samples are taken during the loading of chemicals. When a cargo is contaminated it must be established whether the cargo was effected prior to loading; or during its transportation on board. Cargo transfer hoses may also contribute to cargo contamination, therefore hoses should be properly cleaned in between different cargoes.
Related Info:
Cargo unloading operation safety precautions
Liaison between ship and shore
Preparation for cargo operation
Preparing a cargo tank atmosphere
PV valves operation and maintenance procedure
Ship shore safety checklist while alongside a terminal
Main Info pages!
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Chemicaltankerguide.com is merely an informational site about various aspects of chemical tankers and safety tips that may be particular value to those working in: Chemical Handling, Chemical Storage, Liquefied Chemical Suppliers, Chemical Shipping, Chemical Transportation, Chemical Terminals, Bulk Chemical Services and Chemical Processing. If you are interested in finding out more about chemical tanker guideline please visit IMO official website. For any comment please Contact us
Copyright © 2011 Chemical Tanker Guide.com All rights reserved.
Diesel oil has a flash point of around 63°C and vapours from a volatile cargo can easily change the flash point to below 60°C, causing the cargo to be re-classified. Many lube oils and lube additives are heated during transport. Steam coils are normally used for this purpose. A leaking heating coil can lead to water entering the cargo tank and consequently contaminating the cargo. Laboratory tests should be carried out on cargoes contaminated by water. It should be established whether the water is fresh or salt water. Contamination caused by fresh water is most likely to be caused by a leaking heating coil whereas salt water contamination would probably be caused by a leaking tank hatch, in which case the hatch packing should be checked.
Chemical tankers are normally constructed with completely independent cargo systems. Each cargo tank will have an independent pumping and venting system.
Cargo contamination in chemical tankers are often caused by poor cleaning of cargo tanks or pipe lines. Unfortunately many chemicals are extremely sensitive to contamination, just a few parts per million of a previous cargo can contaminate an entire shipment.
Many cargo samples are taken during the loading of chemicals. When a cargo is contaminated it must be established whether the cargo was effected prior to loading; or during its transportation on board. Cargo transfer hoses may also contribute to cargo contamination, therefore hoses should be properly cleaned in between different cargoes.
Related Info:
Cargo unloading operation safety precautions
Liaison between ship and shore
Preparation for cargo operation
Preparing a cargo tank atmosphere
PV valves operation and maintenance procedure
Ship shore safety checklist while alongside a terminal
Main Info pages!
Home page ||| Chemical hazards ||| Cargo planning & Stowage ||| Cargo loading ||| Cargo documents ||| Safe stability ||| Cargo care ||| Preparation for unloading ||| Inert gas systems |||Gas freeing ||| Nitrogen handling ||| Chemical handling Safe practice |||Handling equipments ||| Cargo & Ballast pumps ||| Cargo tanks |||Tank cleaning |||Special cargoes |||Spills emergencies |||Fire protection
Chemicaltankerguide.com is merely an informational site about various aspects of chemical tankers and safety tips that may be particular value to those working in: Chemical Handling, Chemical Storage, Liquefied Chemical Suppliers, Chemical Shipping, Chemical Transportation, Chemical Terminals, Bulk Chemical Services and Chemical Processing. If you are interested in finding out more about chemical tanker guideline please visit IMO official website. For any comment please Contact us
Copyright © 2011 Chemical Tanker Guide.com All rights reserved.