36. Toxicity Hazards on a Tanker (cd2-5)

C/Off: We will now talk more about toxic gas hazards and safety.

Cruz: Is it hydrogen sulfide?

C/Off: Most crude oil comes from wells with high levels of hydrogen sulfide. But the level is usually reduced by a stabilization process before the crude oil is loaded. If this system fails, however, a tanker may load with a higher-than-usual hydrogen sulfide content. Then special adjustments must be made. Mexican or Qatar crude oil contains high levels of hydrogen sulfide, which smells like rotten eggs. Be very careful not to breathe it because it could paralyze you instantly. One time, when we were at the ullage hole, a man lost consciousness after inhaling the gas.

Cruz: There must be some way to avoid this problem.

C/Off: We have pocket-sized detectors for hydrogen sulfide. You should always have one with you. We are allowed to work when the concentration is less than 10 ppm (parts per million). If you detect more gas than the 10 ppm allowed, you must be very careful.

Santos: That's why I saw oxygen masks at the entrance of the Pump Room. Should we use them in that case?

C/Off: Those masks are used when there is gas present or when there is a fire. They are also useful in the Pump Room if a large amount of oil has leaked and gas is escaping. But even with a mask on, it is still dangerous if there is a lot of gas.

toxic gas hazard(s): dangers associated with poisonous gases

well(s): oil well, a hole drilled into the ground to draw out petroleum

reduced: decreased, made smaller in number or quantity

a stabilization process: a process for making something stable

rotten egg(s): eggs that have gone bad

instantly: promptly, right away, on the spot

lost consciousness: a person losing sensory perception

avoid: not to encounter or experience

detector(s): device used to find something

oxygen mask(s): a mask worn over the nose and mouth for supplying oxygen

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37. Oxygen Deficiency on a Coal-Ore Carrier (cd2-6)

Avarro: Well, we're safe on this ship from accidental oxygen depravation because, as a

coal-ore carrier, it doesn't have an inert gas system.

A/Off: That's crazy! This ship is especially dangerous.

Avarro: Really? Why is that?

A/Off: It's very dangerous in the cofferdams, in the ballast tanks of the double-bottom,

and in the lower stools. Whenever coal is being loaded, there is a danger of

asphyxiation.

Avarro: Why is that? There must be enough oxygen; we go down there all the time.

A/Off: It's rust. Oxygen is consumed when iron rusts. This uses up the oxygen over time.

You have to take special care and measure the oxygen level whenever you enter

these areas. Be sure to check with two oxygen detectors, not just one. And you

must have enough ventilation.

Avarro: How do you ventilate without a fan?

A/Off: We keep the manholes open for a day or more. It's natural ventilation. For

double-bottom tanks, we open both the fore and aft holes to let the air in. Coal

catches fire easily. And fire lowers the level of oxygen and raises the level of

carbon dioxide.

Avarro: That's scary.

A/Off: Yes, it is. Two seamen died once in a lower stool because of a shortage of oxygen.

If they had measured the oxygen properly, placed a watch on deck and prepared

their breathing apparatus, they would be alive today.

depravation: a lack of something

coal-ore carrier: a ship for carrying coal ore

That's crazy! : Nonsense! Don't be silly!

cofferdam(s): a liquid-tight chamber used to prevent oil spills

double-bottom: ship's bottom having a double structure or lining

lower stool(s): a structure enforcing the bulkhead

asphyxiation: a lack of oxygen causing death or loss of consciousness = asphyxia

rust: oxidization of iron

ventilation: circulation of air

carbon dioxide: a chemical substance made of one carbon molecule and two oxygen molecules

scary: making people worried and afraid; frightening

breathing apparatus: device that helps a person to breath (air)