Certificate of Inhibitor Addition
An Inhibitor Information Form is issued by the loading terminal or by the cargo manufacturer. Such a document is shown in 2.6.
Chapter 9
Personal Health and Safety
This chapter mainly concentrates on the quality of the atmosphere to which personnel can be exposed. An issue of major importance; the entry into enclosed spaces, is covered in detail. In addition to the risk to personnel encountering hydrocarbon vapours of a toxic nature, the question of oxygen deficiency is also covered. Methods of checking atmospheres are described.
9.1 CARGO HAZARDS
All gas carriers are designed so that, in normal operation, personnel should never be exposed to the hazards posed by the products being carried. This assumes, of course, that the ship and its equipment are maintained properly and that operating instructions are followed.
In the event of accidental leakage, emergency inspections or maintenance tasks, personnel may be exposed to liquid or gaseous product. It is the purpose of this chapter to review the hazards to health and safety which such circumstances present and to outline means of hazard avoidance.
The overall approach in the avoidance of hazards to personnel should always be, in order of preference:
• Hazard removal
• Hazard control, and then only on,
• Reliance on personal protection.
This listing suggests that reliance of personal protection should only be used in cases where hazard removal or hazard control are found impossible to accomplish.
An essential requirement is the thorough training of all personnel. Effective supervision of all tasks where hazards may be present is also vital. Training should go beyond basic instruction on the use of equipment or the execution of procedures, and should include the nature of the hazards, including those which are sometimes not immediately obvious.
Broadly, the hazards of liquefied gases or their vapours may be five-fold. These hazards are discussed more fully later in this chapter. However, the essential components are listed below:—
• Flammability — see 9.2
• Toxicity (poisoning) — see 9.3.1
• Asphyxia (suffocation) — see 9.3.2
• Low temperature (frostbite) — see 9.4
• Chemical burns — see 9.5
In Chapter Two, a description is given of the properties of the liquefied gas cargoes normally carried. In addition, the Cargo Information Data Sheets in Reference 2.1 and the Medical First Aid Guide (see Reference 1.7) published by IMO provide detailed health and safety data for products. The risks of flammability, low temperature and asphyxia apply to nearly all liquefied gas cargoes. However, the hazard of toxicity and chemical burns apply to only some of them.
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Table 9.1 lists the main liquefied gases together with their flammable and toxic hazards. Where appropriate, asphyxiant hazards are also noted in the column headed 'TLV. However, this applies only when the gas has asphyxiant hazards and is not recorded as having any toxic effects or where the toxic effects are limited.
Table 9.1 Health data — cargo vapour
| Cargo vapour in air | Toxic effects of vapour or liquid | ||||||
| Substance | Flammable | Toxic | Typical TLV-TWA (ppm) | Corrosive/ Irritant | Effects on Nervous System | ||
| Methane | Yes | — | A | No | — | ||
| Ethane | Yes | — | A | No | Yes | ||
| Propane | Yes | — | A | No | Yes | ||
| Butane | Yes | — | 600 | No | Yes | ||
| Ethylene | Yes | — | A | No | Yes | ||
| Propylene | Yes | — | A | No | Yes | ||
| Butylene | Yes | — | 800 | No | Yes | ||
| Isoprene | Yes | — | No Data | — | Yes | ||
| Butadiene | Yes | Yes | 10 | Yes | Yes | ||
| Ammonia | Limited | Yes | 25 | Very | — | ||
| Vinyl chloride | Yes | Yes | 5 | Yes | Yes | ||
| Ethylene oxide | Yes | Yes | 10 | Very | Yes | ||
| Propylene oxide | Yes | Yes | 50 | Very | Yes | ||
| Chlorine | No | Yes | 25 | Very | Very | ||
| Gases shown with an 'A' marked in the 'TLV column do not have recorded TLVs. These gases are relatively non-toxic in character. They are known as Asphyxiant Gases and will kill when their concentration in air is sufficient to displace the oxygen needed to sustain life (see 9.3.2).
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The table is subdivided horizontally by a double line. The products above this line are mainly the hydrocarbon liquefied gases and those below the line are mainly chemical gases. It should be noted that the chemical gases tend to have stronger toxic effects.
The last two columns of the table show how a liquefied gas may affect a person. Broadly, the initial toxic effects on the human body can be corrosive or narcotic (effects on the nervous system). In certain cases, both may apply. In the case of a corrosive compound, depending on exposure and toxicity, its effects may be minor or major. In the case of minor effects, only limited irritation of the skin, eyes or mucous membranes may be felt. An example of a more serious case may be that debilitating effects on the lungs are experienced. In the case of exposure to a narcotic gas, the major initial effect is on the body's nervous system. In such cases, severe dis-orientation and mental confusion can result. The corrosive and narcotic effects are worthy of note. They are of help in identifying the gas to which a person has been exposed and, additionally, they help in identifying proper medical treatment (see 9.3.3).
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