Cathodic protection/Shoring

Question 1

Purpose of cathodic protection system

Answer 1

Impressed current cathodic protection system (ICCP) is fitted to ships to minimise the amount of corrosion of steel that takes place in seawater.
* Ship has zinc anodes ,they are sacrificial & can be replaced
* Anodes send out a negative charge to prevent corrosion

Question 2

3 Types of shoring build

Answer 2

1. Vertical shoring-For hatches & decks with leak stopping devices on them.(used for vertical structures)
2. Square shoring-for bulkheads,shipside plating & water tight doors
3. Cantilever shoring-For when it is difficult to access damaged area

Question 3

When would you use Square shoring?

Answer 3

For holding doors shut or stopping flooding from entering through the side plating

Question 4

When would you use Vertical shoring?

Answer 4

Flooding coming from compartment below

Question 5

When would you use Cantilever shoring?

Answer 5

When it is difficult to access the leak, so using a clamp attached to the ships frame to hold a wood block to stop flooding

Question 6

Why would you use shoring?

Answer 6

When the structure has been weakened,& needs temporary support until more permanent measures are possible

Question 7

Explain Cathodic protection

Answer 7

Protects the hull by forcing it to become a cathode because oxidisation only happens on a anode.

• Pump electrons into the metal you want to protect
• Using a sacrificial anode (Zinc),it is more reactive than the hull when it reacts with the S/W it will start to oxidise generating electrons that flow to the hull making the hull become a cathode