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Safety precautions for hot work onboard chemical tankers

Hot work means any work requiring the use of electric arc or gas welding equipment, cutting burner equipment or other forms of naked flame, as well as spark generating tools. It covers all such work, regardless of where it is carried out on board a ship, including open decks, machinery rooms and the engine room.

Performing hot works onboard modern chemical tankers involved numerous hazards .It is anticipated that owners and operators of chemical tankers will issue clear guidance to masters and crews on the control of hot work on board while the ship is in service. The following is intended to assist safety by indicating principal areas that should receive attention.

chemical tanker navigation at sea
Hot work requirement

Repair work outside the main engine room which necessitates hot work should only be undertaken when it is essential for the safety or immediate operation of the ship, and when no alternative repair procedure is possible.

Hot work onboard chemical tanker
Fig : Hot work onboard chemical tanker

Hot work outside the engine room (and in the engine room when associated with fuel or lubrication systems) must be prohibited until the requirements of national legislation and other applicable regulations have been met, safety considerations taken into account, and a hot work permit has been issued. This may involve the master, owner's superintendent, shore contractor, terminal representative and port authority as appropriate.

Hot work in port at a chemical terminal is normally prohibited. If such work becomes essential for safety or urgent operational needs, then port and terminal regulations must be complied with. Full liaison should be established with port and terminal authorities before any work is started.

Assessment of hot work

The master is responsible for deciding whether the hot work is justified, and whether it can be conducted safely. Hot work in areas outside the engine room should not be started until a procedure has been discussed &nd agreed, and the master has informed the ship's owners or operators of details of the work intended.

Before hot work is started a safety meeting under the chairmanship of the master must be held, at which the planned work and the safety precautions are carefully reviewed. The meeting should be attended at least by all those who will have responsibilities in connection with the work. An agreed written plan for the work and the related safety precautions should be made. The plan must clearly and unambiguously designate one officer who is responsible for the supervision of the work, and another officer who is responsible for safety precautions and communications between all parties involved.

All personnel involved in the preparations and in the hot work operation must be briefed and instructed on their own role. They must clearly understand which officer is responsible for work supervision and which for safety precautions. A written hot work permit should be issued for each intended task. The permit should specify the duration of validity, which should not exceed a working day.

Preparations for hot work

No hot work must be undertaken inside a compartment until it has been cleaned and ventilated. Tests of the atmosphere in the compartment should indicate 21% oxygen content by volume, flammable vapour as low as possible but not more than 1% LFL, and that the compartment is free from toxic gases. It is important to continue ventilation during hot work.

No hot work should be undertaken on the open deck unless the area is free from flammable vapour and all compartments (including deck tanks) within a specified radius around the working area have been washed and freed of flammable vapour and/or inerted. Company or national regulations may give guidance on this distance. If no guidance is available, then the advice in ISGOTT should be taken into account

All sludge, cargo-impregnated scale, sediment or other material likely to give off flammable or toxic vapour, especially when heated, should be removed from an area of at least 10 metres around all hot work. All combustible material such as insulation should either be removed or protected from heat.

Adjacent compartments should either be cleaned and gas freed to hot work standard, or freed of cargo vapour to not more than 1% LFL and kept inerted, or completely filled with water. No hot work should be undertaken in a compartment beneath a deck tank in use.

Care should be taken to ensure that no release of flammable vapour or liquid can occur from non-adjacent compartments that are not gas free.

An adjacent fuel oil bunker tank may be considered safe if tests using a combustible gas indicator give a reading of not more than 1% LFL in the ullage space of the bunker tank, and no heat transfer through the bulkhead of the bunker tank will be caused by the hot work. No hot work should be carried out on bulkheads of bunker tanks that are in use.

All pipelines interconnecting with cargo spaces should be flushed, drained, vented and isolated from the compartment or deck area where hot work will take place.

Hot work on pipelines and valves should only be permitted when the item needing repair has been isolated from the system by cold work, and the remaining system blanked off. The item to be worked on should be cleaned and gas freed to a standard that is safe for hot work, regardless of whether or not it is removed from the hazardous cargo area.

All other operations utilising the cargo or ballast system should be stopped before hot work is undertaken, and throughout the duration of the hot work. If hot work is interrupted for any reason for an extended period, hot work should not be resumed until all precautions have been rechecked and a new hot work permit has been issued.

Checks by officer responsible for safety during hot work

Immediately before hot work is started, the officer responsible for safety precautions should examine the area where it is to)De undertaken, and ensure that tests with a combustible gas indicator show not more than 1% LFL, and, if the work is inside an enclosed space, that the oxygen content is 21% by volume.

Adequate fire fighting equipment must be laid out and ready for immediate use. Fire watch procedures must be established for the area of hot work and in adjacent, non-inerted spaces where the transfer of heat may create a hazard. Effective means of containing and extinguishing welding sparks and molten slag must be established.

The work area must be adequately and continuously ventilated. Flammable solvents must not be present, even for use in cleaning tools.

The frequency with which the atmosphere is to be monitored must be established. Atmospheres should be retested at regular intervals and after each break in work periods. Checks should be made for flammable vapours or liquids, toxic gases or inert gas from non-gas free spaces.

Welding apparatus and other equipment to be used should be carefully inspected before each occasion of use to ensure that it is in good condition and, where required, correctly earthed.

Bottles containing Acetylene– A colourless, poisonous gas used with oxygen for oxy-acetylene metal welding or cutting should be checked prior hot work. Flash back arrestor must be fitted and in good working condition.

Special attention must be paid to electric arc equipment to ensure that:

• Electrical supply connections are made in a gas free space.

• Existing supply wiring is adequate to carry the electrical current demanded without overloading and consequent heating.

• Flexible electric cables laid across the deck have sound insulation.

• The cable route to the work site is the safest possible, only passing over gas free or inerted spaces.

After compeletion of hot work

The work area should be secured, and all special equipment used should be removed. The ship's owner or operator should be informed of the completion of all hot work allowed by the hot work permit.

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