Cathodics

Question 1

What is the purpose of cathodics?

Answer 1

To reduce corrosion of metal surfaces with anodes

Question 2

How do cathodics work?

Answer 2

ICCP sends a small voltage through the ships Hull with a negative charge through TRUs

This prevents corrosion and marine growth like barnacles

Question 3

How many anodes are around the ship?

Answer 3

12 anodes - 6 STBD, 6 PORT
12 Reference - 5 STBD, 5 PORT, 2 AFT near propellers

Question 4

How are cathodics readings taken?

Answer 4

Taken as a daily from each TRU for the part of the ship its supplying

Readings will make trends to show the output performance and any major change will be shown on the trend

Can also be taken from the CC, and logged on periodic records

Question 5

Cathodics Routines

Answer 5

Dailys:
CCU readings,
checking earth strappings,
condition of panel integrity
checking air vents aren’t obstructed

Monthly -
Manual dips between anodes and reference cells to ensure daily readings are the same as manual ones

Question 6

SHIPHAZ

Answer 6

Divers down and other procedures require a tag out and isolations in the key lock in SCC

Question 7

TRUs are powered by local switchboards. Locations.

Answer 7

8NC3 -> 8N1
8KC0 -> 7CA1. EDPs
8CX0 -> 8KA2

Question 8

Where is the CCU

Answer 8

8K

Question 9

In Rosyth, TRUs are set at:

Answer 9

Unit 1 - mV 940
Unit 2 - mV 930
Unit 3 - mV 920

Question 10

Cathodics protect…

Answer 10

Hull, sea chests, Ballast tanks

Question 11

2 types of cathodic system

Answer 11

Sacrificial Galvanic Protection
Impressed Current Cathodics protection

Question 12

What are Sacrificial anodes made from?

Answer 12

Aluminium or zinc alloy with a higher active voltage than the metal they are protecting

Question 13

Sacrificial Anode lifespan

Answer 13

6 years
They are supposed to deteriorate, its part of their function

Question 14

How many anodes are there?

Answer 14

52 Zinc in external hull
372 aluminium in Ballast tanks (heavy)
30 aluminium in Ballast tanks (light)
145 Zinc in sea chest

Question 15

How are anodes fitted?

Answer 15

Ballast tanks bolted
Sea ches and Hull welded

Question 16

What are ICCP anodes made from?

Answer 16

Coated titanium

Question 17

What power does TRUs use?

Answer 17

24V DC, 75 Amps

Question 18

ICCP has 3 TRUs, what are they?

Answer 18

Main Control PCB
Control PCB
Thyristor PCB

Question 19

What does main Control pcb do?

Answer 19

Controls operation, and gives signals to Thyristor Driver pcb, which allows output of current and voltage

Question 20

Control pcb purpose

Answer 20

Monitors and allows Control over the system

Question 21

Thyristor pcb purpose monitors

Answer 21

Monitors and conditions signals for Thyristor unit

Question 22

Reference Electrodes locations

Answer 22

C AMS - 8C - 150AMPS - 2 ANODES (A11/12)
K AMS - 8K - 300 AMPS - 4 ANODES (A7-10)
N AMS - 8N - 450 AMPS - 6 ANODES (A1-6)
CCU - 8K