Content of Bridge Procedure Guide

Contents of Bridge Procedure Guide

Contents of Bridge Procedure Guide

Bridge Procedure Guide:- The Bridge Procedures Guide (BPG) is an International Chamber of Shipping (ICS) publication that aims to reflect Best Practice aboard Merchant Ships embracing standards and recommendations promoted by the IMO. This includes the concept of ‘continuous improvement’ as described in the ISM Code and the watchkeeping requirements of STCW Chapter VIII.

The international maritime dangerous goods (IMDG) code.


The International Maritime Dangerous Goods or IMDG Code was adopted in 1965 as per the SOLAS (Safety for Life at Sea) Convention of 1960 under the IMO.

The IMDG code also ensures that the goods transported through seaways are packaged in such a way that they can be safely transported.


  • The seafarer should be able to classify dangerous goods and identify the shipping names of dangerous goods.
  • He/she should know how the particular IMDG cargo should be packed, Marked, lebelled, stowed and segregated.
  • He should understand different types of markings, labels or placards used to address various dangerous goods
  • Must know safe practice to load/unload the cargo unit carrying the IMDG product


The dangerous goods code is a uniform code. This means that the code is applicable to all cargo-carrying ships around the world.


  • Class 1 is for explosives. The same classification has six sub-divisions for materials which pose a high explosive risk, low explosive risk. Example RDX, Ammunition.
  • Class 2 is for gases. compressed, liquefied or dissolved under pressure.This clause has three sub-categories that talk about gases that are highly inflammable, that are not inflammable and gases that neither inflammable nor toxic
  • Class 3 is for Flammable liquids and has no sub-divisions.
  • Class 4.1 Flammable liquids – Zinc dust, Textile waste, Paints
  • Class 4.2 Substance liable to spontaneous combustion Iron and steel.
  • Class 4.3 Substance which in contact with water emit flammable gases – Sodium, Potassium, Calcium.
  • Class 5 .1 is for substances that have the oxidizing substance example – Sodium peroxide.
  • Class 5.2 Organic peroxides like Peroxyacetic Acid , Decanoyl peroxide.
  • Class 6.1  is for all kinds of substances that are toxic example tear gas.
  • Class 6.2 Infectious substance – Biological substances.
  • Class 7 is specifically for materials that are radioactive – Thorium, Isotopes of cesium.
  • Class 8 is for materials that are corrosive – Sulphuric acid, Caustic soda.
  • Class 9 is Miscellaneous Dangerous substances like fertilizers.




  • Packaging should be constructed and closed so as to prevent loss of contents by vibration or by change in temperature, humidity or pressure under normal transport condition.
  • No residue of dangerous cargo shall stick to the outside of packages, whether new, reused, reconditioned or remanufactured.
  • Part of the packing that is in direct contact with the dangerous good should not get affected. (weakened, react, Penetrate etc)
  • Packaging should be successfully tested for Vibration, Drop test as provided in the code.
  • Cushioning and absorbent material should be inert and suitable to nature of content.
  • Nature and thickness of the packing should be enough to withstand heat generated due to friction while transporting without any problem.
  • Dangerous goods should not be packed together with other substance if they react dangerously .
  • Ullage should be kept sufficient for expansion during transportation.


  • Label shows the class number and dangerous properties of the goods in pictorial symbols as illustrated in the code.
  • They are 100mm by 100mm
  • Placards are 250mm by 250mm, contains the same information but in a bigger size and are fixed to the cargo transport unit.
  • The proper shipping name and UN number should be marked.
  • These marking, lebels & placards shall be readily visible.
  • Marking, lebels, placards should be still identifiable if kept immersed in sea water for 3 months.
  • Large packaging should be marked on two opposing sides and Placards on a CTU (Cargo Transport Unit) shall be placed on four sides.
  • IBC packaging should be marked on two opposing sides and Placards on a CTU (Cargo Transport Unit) shall be placed on four side.
  • Radioactive materials shall be marked with the name of consignor or consignee or both if over 50Kgs


  • A dangerous good transport document includes a paper document as well as provision of the same information by Electronic data processing.
  • If offered as Electronic means , consignor must be able to present paper documents without delay.
  • Document must contain the below data in sequence –
    • Name and address of consignor and consignee of dangerous goods.
    • Date when it was prepared.
    • UN number (Always starts with UN)
    • Proper shipping name
    • Technical name
    • Primary hazard class, division and compatible group
    • Subsidiary hazard class or division
    • Packaging group
    • Total quantity of dangerous good


  • Stowage means proper placement of DG good to ensure safety of ship, cargo and environmental protection during transport.


The IMDG Code defines “segregation” as the process of separating two or more substances or articles which are considered mutually incompatible wen their packing or stowage together may result in undue hazards in case of leakage, spillage or any other accident. Segregation is obtained by maintaining certain distances between incompatible dangerous goods, by requiring the presence of one or more steel bulkheads or decks between them, or a combination of the previous methods.

Segregation of IMDG cargo, Credits –

To determine the segregation for two classes, you would read a row for one class (across) and for the other class read a column (down). Where they intersect, you will either find the letter “X” or a number. The numbers (1, 2, 3 or 4) will tell the people stowing the goods how far apart they must be separated, as follows:

“1” – “away from” (normally, CTUs at least 3 metres apart)

“2” – “separated from” (normally, CTUs at least 6 metres apart)

“3” – “separated by a complete compartment or hold from”

“4” – “separated longitudinally by an intervening complete compartment or hold from”


MIST – Mist is said to exist when visibility is reduced by water particles that have condensed on the dust, minute salt particles of salt.

When due to mist the visibility reduces below 1 km, it is called FOG. Mist occur when relative humidity is as low as 80%. Radius of water droplet is less than 1 micron.

Fog occurs when relative humidity is 90% or more and the radios of the droplet is between 1 to 10 microns.

What are the types of fog?

Radiation Fog

  • Radiation fog is also known as land fog.
  • It forms over land only.
  • During the night, land gives off its heat very quickly (On clear night it cools more rapidly) .
  • The air in contact with the ground gets cooled and if cooled below its dew point, so large quantity of dew is deposited.
  • Now when light breeze is blowing, turbulence causes the cold from the land surface to be communicated to the air a couple of meters above the ground. So it is called ground fog.
  • If wind is bit stronger, radiation fog may extend upto a height of about 150m.
  • Strong wind causes too much turbulence which leads to formation of cloud – Stratus Type.

Advection Fog

  • It is also called sea fog because it is mostly found over sea. It can however form over land also.
  • It is formed when moist wind blows over a relatively cold surface of sea or land.
  • When most air is cooled below its dew point, the excess water vapour condenses into small droplet of water on the dust or minute particles of salt, resulting in Advection fog.
  • Wind cause advection fog to form and also to spread.
  • However very strong wind can lead to formation of clouds stratus type.
  • Example of advection fog are –
    • Off the east coast of japan where the warm, moist Westerlies, blowing over the warm Kuro Shio, cross over the cold Oyo Shio.
    • On the Grand bank of New Foundland where the warm, moist westerlies, blowing over the warmGulf stream, crosses over the cold Labrador current.


  • Smog is radiation fog mixed with Industrial smoke
  • Smoke + Fog = Smog
  • Example of places – London, Kolkata, Tokyo, Newcastle, Glasgow.

Steam fog or Arctic sea smoke

  • When very cold dry air passes over relatively warm sea surface, The water surface evaporating from sea is quickly condensed into water droplet.
  • It appears as if vertical streaks if smoke are rising from the sea surface. This is called steam fog or Arctic sea smoke.

Hill or Orographic fog

  • When wind comes against a mountain or hill and begins to climb over it, It cools adiabatically.
  • After it reaches dew point, any further cooling causes excess moisture to condense into water droplets forming hill fog or Orographic fog.

What is Saturation and Dew point ?

When relative humidity of air becomes 100%. The air is said to be saturated and the temperature at which this occurs is called the due point temperature.

Relative humidity is the percentage ratio of the actual water vapour contained in the given sample to the maximum quantity of water vapour that the sample can hold at that temperature.

RH% = Present quantity of water vapour / Max possible at that temperature * 100

What is DALR and SALR.


It has been observed that the temperature of a dry parcel of air, Which is made to rise, falls at a steady rate of 10°C for every km of ascent i.e., The adiabatic lapse rate of a dry parcel of air, or Dry Adiabatic Lapse Rate(DALR) is 10°C per KM.


The temperature of a saturated parcel of air, Which is made to rise, falls at a rate approx 5°C per KM.

Why is SALR less than DALR ?

SALR is less than DALR because, as the saturated air is cooled, its capacity to hold water vapour decreases and the excess moisture condenses into water droplets. This condensation releases latent heat that warms up the parcel of air. That is the reason SALR falls @ 5°C per KM. Where as DALR falls at 10°C per KM.