Basic Knowledge of Hazard Controls

Hazard control on tankers involves identifying, assessing and implementing measures to reduce risks and ensure the safety of crew, the environment and cargo. Hazard control measures on tankers include regular safety inspections, equipment maintenance, use of personal protective equipment, implementation of safety procedures and protocols, conduct of safety drills and drills, monitoring of cargo operations and compliance with regulatory requirements. Effective hazard control is essential to prevent accidents, spills and other incidents on tankers.

Cargo/Material Safety Data Sheets

• Information about cargoes to be handled is essential to the safety of vessel and her crew.
• Such information maybe found on ICS or other cargo data sheets for each product, which also include all necessary data for the safe handling and carriage of the cargo.
• Cargo information for most tanker cargoes is kept on board and available for all concerned.
• Cargo will not be loaded unless sufficient information necessary for its safe handling and transportation is available.
• The responsible officer will see to it that the necessary cargo information is posted on the notice board prior to cargo operations.
• All personnel engaged in cargo operations should familiarize themselves with the cargoes by studying the ICS or other Cargo Data Sheets.
• Cargo information is fundamental in cargo planning.

Material Safety Data Sheets

In addition plentiful notes are included governing tankcleaning hazards, protective clothing needed, cargo compatibility etc. for certain dangerous cargoes. This guide should be consulted as a definite source for anyone requiring detailed information about full range of cargoes.

Material Safety Data Sheets

• Contains physical and chemical properties of chemical cargoes.
• For each cargo the following data are given:
  • Appearance and odour.
  • The main hazards.
• Emergency procedures, to be adhered to when the following occur:
  • Fire.
  • Liquid in eye.
  • Liquid in skin.
  • Vapor inhaled.
  • Spillage.
  • Fire and explosion data.
  • Chemical data.
  • Reactivity data.
  • Health data.
  • Effect of liquid.
  • Effect of vapor.
  • Physical data.
  • Handling and storage requirements.
  • Handling and storage material.

Phenol

• Un nummer – 2 312.
• Mfag table number – 710.
• Marine pollution category – 8.
• Аppearance – Liquid or white crystalline soud.
• Odour – Sharp, like disinfectant.
• Synonyms – benzophenol carbolic acid hydroxybenzane monohydroxybenzene phenylic acid.

THE MAIN HAZARDS – Liquid or aqueous solution causes very rapid severe poisoning which can be fatal by skin contact. Causes severe damage to eyes and skin.

Phenol – Cargo Data Sheet (ICS) for Phenol

Notes:

1. The information on this dats sheet is for 100 % phenol, but it may be shipped as 80 % to 90 % squeous solutions, or in solution with cresois.
2. Where, for any reason, the solvents recommended are not immediately available, rub the skin with swabs soaked in water. This treatment should be the folowed, as soon as possible, by rubbing With swabs soaked in one of the recommended solvents.
3. The designation «skin» refers to the potential contribution to the over-all exposure by the cutaneous route inciudi mucous mambrines end eye, either by sir-borne of, more particularly, by direct contact with the substance.
4. Those affected with liver or kidney diseases should not be exposed to phenol for any length of time; even intermittent exposure to the vapours may become dangerous.
5. The vapour may condense and solidify causing blockage of flame screens and pressure vacuum valves. There have been no reports of this in practice. It should also be noted that water depresses the freezing point.
6. Phenol is partly miscible in water at ambient temperatures. At 20 °C the phanol-rich layer contains about 72 % and the squeous layer about 8 % of phenol. it is completely miscible at temperatures greater than shout 66 °C.
7. For at handling operations, gloves, boots and suits of rubber or PVC end head and face protection should be worn.

Methods of controlling hazards on tanker

Inerting

• The introduction of inert gas into a tank with the object of attaining the inert condition.
• By filling the cargo tank and associated piping systems and the spaces surrounding the cargo tank, with gas or vapour which will not support combustion and which will not react with the cargo, and maintaining that condition.

Padding

• Filling and maintaining the cargo tank and associated piping system with a liquid, gas (inert gas) or vapour (liquefied gas), which separates the cargo from air.

Drying

• Filling the cargo tanks and associated piping systems with moisture free gas or vapour with a dew point of -40 °C or below at atmospheric pressure, and maintaining that condition.
• To removed moisture from the tanks that may form hydrates in liquefied gas.
• Dry Nitrogen, Dry air (oxygen).

Monitorin

• To monitor cargo and associated systems by means of taking its Temperature, Ullage, Pressure, & for the irregularities around the tanks.

Read also: Properties of liquefied gases

Anti-static measure

• The electricity produced on dissimilar materials through physical contact and separation Bonding, Grounding & earthing.

Ventilation

• Forced or natural.
• Rapid dilution by air to disperse harmful or flammable cargo vapours vented to the atmosphere is essential to safety. The most critical problem is that of dispersing the high concentrations of vapour, that are vented during the final stages of loading or during gas-freeing operations involving flammable or harmful cargoes.

Segregation

Segregating to avoid contamination & for cargoes that are reactive with each other.

Cargo inhibition

Inhibitor – General term for compound or materials that have the effect of slowing down or stopping undesired chemical changes such as corrosion, oxidation or polymerization.

Certain hydrocarbon compound has a tendency to polymerize with time, accelerated by heat, light, sometimes air or other.

Catalyst – a substance that starts a reaction or changes its speed without being itself chemically changes.

Importance of compatibility of materials

Construction material used for the containment of cargo

• Chemical Tankers – stainless, zinc coated, phenol coated & epoxy coated tanks.
• Liquefied gas tankers – Nickel alloy.

Explosion and Fire on Deck

A vessel was loading propane in still weather at a sheltered jetty. The final tank was being completed but due to failure by the officer concerned the tank was allowed to overfill, the safety valve lifted and liquid started to erupt from the vent stack. The liquid and vapour escaping from the vent stack rolled down the shipside and was ignited by an internal combustion engine running on a craft moored alongside.

There has been more than one incident of this nature recorded where escaping vapour has been drawn into the air inlet of a petrol or diesel engine resulting in the engine over speeding due to the governor which, shuts down-and the fuel supply under normal circumstances having no control over the gas air mixture being drawn in via the air manifold of the engine.

The engine in these circumstances increased speed and finally disintegrated. The vapour in the surrounding atmosphere was ignited and flashed back to the outlet of the vent stack which was, fitted with a flame screen. A fire at the top of the vent stack was being fed with vapour or possibly liquid droplets due to over pressure in the cargo tank.

Author

Olga Nesvetailova

Freelancer

Literature

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