What is cofferdam in ship construction?

A cofferdam means an empty space provided in a ship so that compartments on each side have no common boundary; a cofferdam may be located vertically or horizontally. This empty space avoids intermixing of two different fluid when there is a leak from the boundary separating the two liquids.

What is the least you must do before entering a cofferdam in engine room?

If it is an empty ballast tank or a cofferdam in which water has leaked it will contain carbon dioxide. Risk assesment for the entry must be carried out. The space must be vented using a portable blower for at least 8 to 12 hours . The space must be tested for oxygen content, using an oxygen meter.

What are the requirements of cofferdam?

Criteria for Selection of Cofferdam Types

• Depth of water.
• Depth and size of excavation.
• Soil type.
• Velocity of flow in waterway.
• Tide levels.
• Risk of damage by floating debris or ice.
• Availability of construction materials.
• Ease of transportation of construction materials.

What is the use of cofferdam in ship?

To avoid the above-mentioned situation is a void or empty compartment is provided between the tanks to prevent two different liquids from mixing with each other. This space is known as a cofferdam. Space avoids intermixing of two different liquid when there is a leak from the boundary separating the two liquid.

How are cofferdams used in ship repair operations?

The role of cofferdams in ship repair operations. When a structure has to be built beneath the water surface, a cofferdam is created. A cofferdam is a temporary watertight structure designed to keep water and/or soil out of the excavation in which a structure is built.

Where is the cofferdam dam on a ship?

Cofferdam dam is there on all the ships. They are provided: • Between fuel oil tanks which are installed inside the engine room. E.g. diesel oil and heavy fuel oil tank. • The cofferdam is also installed around the main engine lube oil drain or sump tank, mainly to separate it from other double bottom tanks.

How big should a cofferdam be on a ship?

The size of the Cofferdams shall be of sufficient enough for easy access for inspection, and they shall cover the entire adjacent tank bulkhead. The minimum distance between bulkheads should be 600 mm. Manholes and lightening holes are also provided in the cofferdam.

What are the requirements for a cofferdam construction?

• Specification Requirements – Subsection 704 Steel Sheet Piling and Cofferdams • Provide new or used continuous interlocking steel sheet piling including connections in corner pieces. Used sheeting must be in good conditions.