OPINION FROM LLYOD’S HANDBOOK ON COAL AND COKE
COAL
All classes of coal are liable to spontaneous combustion, the softer types to a greater extent than others, and therefore adequate ventilation of holds is essential to minimize this risk. If damaged by heating or combustion, the damaged portion should be separated as soon as possible from the sound portion, to prevent further spread of the damage. Coal shipped in a wet condition may be subject to a loss in weight by evaporation, but the comparison of analyses taken prior to loading and after delivery can determine to a large extent the approximate loss in weight. It must be borne in mind, however, that the loading or discharge of coal in rain can result in an increase in discharge weight over shipped weight. Some classes of coal, especially the gas type, suffer deterioration or depreciation by contact with salt water, but are hardly, if ever, affected by contact with fresh – water. A certain normal loss is to be expected through the operation of loading and discharge. This loss can be ascertained by a comparison with the average loss on delivery which is normally found. Particular care should be exercised in arriving at depreciation or loss arising out of heat, fire or water damage. In the case of heat and fire, the first would be a loss of calorific value, to determine which the assistance of analyst or chemical consultants is essential. In dealing with loss or damage to this commodity too much reliance should not be placed on tallies or casual tests, and agreement should only be reached after proper analysis.
COAL TAR
A residue from coal or oil, which is highly adorous and detrimental to other cargoes, and varies it consistency form semi – liquid to hard. Packed in second hand metal drums. According to the wear of these drums loss through leakage may be more or less considerable. The usual causes of leakage are the wear of the drums, the wear of the stopper, and the weakness of the ribs. The most suitable packing for the tropics are sealed metal drums.
COKE
Will absorb moisture up to approximately 20% of its weight, and similarly can lose the same amount of weight.
OPINION FROM THOMAS STOWAGE, HANDBOOK ON COAL AND COKE
COAL
The carriage of coal is attended with risk both of fire and explosion, the loss of many lives and fine vessels being due to these causes.
While all classes of coal, even anthracite are subject to spontaneous combustion, certain classes, particularly some of those shipped from Calcutta, Virginia, U.S.A., the Clyde, and N.S.W. are very liable to spontaneous ignition, so that all vessels, more especially those proceeding on a ling voyage, should have suitable provision, made before loading, to enable temperatures to be taken at the bottom of and at the ends of each coal carrying compartment, by which means any rise of temperature can quickly be detected. Temperature should be taken and recorded frequently throughout the voyage. Coal emits an inflammable gas (marsh gas) particularly immediately after loading and when newly worked or freshly broken, which gas, when mixed with the certain proportion of air, will quickly explode if brought into contact with a spark or light.
The heating of coal and consequent risk of spontaneous ignition does not proceed form the presence of the gas, such being caused by absorption of oxygen from the air, the absorption being greater at high than at low temperature – this in time causing more gas to be evolved.
No additional risk of fire need be apprehended on account of coal being shipped in wet condition or becoming so in the course of the voyage.
The danger of explosion can be best be averted by ample surface ventilation, for which purpose there should be fitted not less than two large ventilators at each end of every compartment, and when conditions permit, by uncovering the hatches to facilitate the escape of gas. The use of naked lights should be kept under careful control. This gas often finds its way into obscure peaks, storerooms, etc., particularly during or shortly after loading, so that such compartments should be kept well ventilated at all times when coal is carried.
A number of Davy lamps should be carried on every coal – carrying vessel.
Explosives are not permitted to be carried in a hold containing coal, in any compartment over that in which coal is carried, nor in one that is not separated form a coal compartment by a steel bulkhead.
Coal – Dust – Vessels carrying part cargoes of coal, or bunker coal, which is separated form other cargo by wooden bulkheads should have the latter in a perfectly dust – tight condition, otherwise claims for coal dust damage will likely result. Cases have occurred where vessels have been declared “Unseaworthy” on it being proven that such wooden bulkheads were not dust – proof and of proper construction at the time vessel loaded her cargo.
Wet Coal – Coal shipped in wet condition will turn out about 3 percent less in weight. BsL should adequately cover ship against any claims for short delivery arising from this cause.
The stowage factor of coal, depending as much as it does upon trimming, varies considerably for the same class and port. In confined ill –designed bunkers, it often greatly excess the accepted figure, while in respect of 2 and 3 deck vessels it is considerable higher than for single deck vessels, or the large bulk carriers.
The accepted stowage factors of various coals are shown below but these are often exceeded to a substantial extent.
COKE
If over stowing with other cargo, coke should be well trimmed and boarded over owning to the tendency of coke to settle down, it is not suitable for over stowage with weighty cargo. Coke absorbs moisture up to about 20 percent of its weight; this should be taken into account when carrying a large deck cargo of coke in a tender vessel. Cotton or fine fibre cargo should not be stowed in the same compartment, and adequate steps should be taken to prevent coke dust from coming into contact with any cargo which is stowed in its vicinity.