Dry Cargoes Hazards

Recently, there has been a marked development in the variety of bulk cargoes carried by sea and now they constitute a significant proportion of international sea trade. While the vast majority of these shipments are made without incident, there had been a number of serious casualties which resulted not only in the loss of the ship but also in loss of life.

Because of these dangers, IMO has developed the Code of Safe Practice for Solid Bulk Cargoes (BC Code) which provides guidance on the standards to be applied in the safe stowage and shipment of solid bulk cargoes excluding grain which is dealt with separate rules.

The BC Code identifies three categories of hazards arising from the carriage of dry cargoes in bulk.

Structural damage due to improper distribution of the cargo. Structural damage may be caused by the high density of many bulk cargoes due to incorrect distribution and inadequate trimming which lead to local overstressing of the ship's structure. Ships are generally provided with information so as to be able to avoid overstressing. Where this is not the case, the BC Code provides the necessary guidance.

Loss or reduction of stability due to shifting. Causes of loss or reduction of stability:

1. The tendency of cargoes to shift in a seaway because of their angle of repose* and other factors. Cargoes should always, as a matter of principle, be trimmed reasonably after loading.

2. The tendency of cargoes to liquefy which results in free surface effects and in cargo shifting.

The tendency of a cargo to liquefy is expressed by its flow moisture point and in order to carry cargoes safely the actual moisture content must be well below this point. The transportable moisture limit represents the maximum moisture content of a material which is considered safe for carriage in ships not specially fitted.

Chemical reactions due to the properties of the cargoes. Materials possessing chemical hazards have designated classes in accordance with the IMDG Code. In addition, there is a class called Materials Hazardous only in Bulk (MHB). As implied by the name, materials under this class pose chemical hazards only when carried in bulk. Like packaged dangerous goods, materials possessing chemical hazards must comply with stowage and segregation requirements. Additionally, special equipment may have to be on board when carrying such cargoes.

Notes

* angle of repose - кут натурального відкосу

16 Read the text again and complete the table.

Dry Cargoes Hazard	Reasons	Precautions

17 In pairs, discuss.

What are possible consequences of:

1. structural damage due to improper distribution of the bulk cargo?

__________________________________________________________________________________________________________________________________________________________

2. loss or reduction of stability due to shifting?

__________________________________________________________________________________________________________________________________________________________

3. chemical reactions due to the properties of the cargoes?

__________________________________________________________________________________________________________________________________________________________

18 In groups, share your practice experience on hazards met while transportation of dry bulk cargoes.

Vocabulary

19 Write down the definitions.

1. to exclude ___________________________________________________________________

2. distribution __________________________________________________________________

3. trimming ___________________________________________________________________

4. overstressing ________________________________________________________________

5. to liquefy ___________________________________________________________________

6. to pose ___________________________________________________________________

7. segregation __________________________________________________________________

8. reduction ___________________________________________________________________

20 Match the synonyms.

1 to pose	a) decrease
2 distribution	b) to melt
3 reduction	c) to present
4 segregation	d) allocation
5 overstressing	e) separation
6 to liquefy	f) to delete
7 trimming	g) overloading
8 to exclude	h) levelling

21 Write down some word-combinations with the words below.

1. segregation__________________________________________________________________

2. reduction ___________________________________________________________________

3. distribution __________________________________________________________________

4. to exclude ___________________________________________________________________

5. to pose _____________________________________________________________________

22 Underline the proper words.

1. Last voyage inadequate trimming led to local overstressing/segregation of the ship's starboard side structures.

2. BC Code poses/excludes guidance on the standards to be applied in the safe stowage and shipment of grain.

3. Materials overstressing/posing chemical hazards only when carried in bulk must comply with stowage and segregation/distribution requirements.

4. As a stringent rule, cargoes should always be liquefied/trimmed properly after loading.

5. Concentrates and certain ores may exclude/liquefy thus the actual moisture content must be well below moisture point.

6. Stability reduction/trimming is caused by shifting of cargoes in a seaway because of their angle of repose.

7. High density of many bulk cargoes due to incorrect distribution/reduction may lead to structural damage of the ship’s structures.

23 Ask and answer adding a professional question.

What is trimming? Have you ever trimmed any cargo?

How do you understand overstressing? When can it appear?

What is meant by segregation? What materials did you use for it?

· to liquefy

· distribution

· to exclude

· reduction

24 Discuss.

What is a can test?

25 Read the case and match the photos with proper descriptions.

Дата добавления: 2015-10-29