Corrosion Resistant Steel for Pitting Corrosion on COTs of Crude Oil Carrier

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Corrosion Resistant Steel forPitting Corrosion
on COTsof Crude Oil Carrier

• The NSGP-1Nippon Steels Green Protect-1

Nov. 2008
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Outline of the NSGP-1
A typical example of chemical analysis, AH32
(mass)

Chemical composition of NSGP-1 meets the IACS
rule
NSGP-1 provides superior corrosion resistance
(NaCl 10wt. pH around 0.8)
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NSGP-1 has been applied to actual vessel(All
COT bottom have been built with NSGP-1)
Ship TAKAMINE (Built by Mitsubishi Heavy
Industry) Construction completed with
no problem 3 and 4 COTs without
painting 1st Dock inspection at 2.3 year after
launching
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NSGP-1 Inspection result after 2.3 years
service
Very low frequency Only shallow pits
No need to repair
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2nd Inspection

• After 4.2 years service

Inspected Area
3P 4P
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NSGP-1 No pit over 4mm depth even after 4.2 years
1400
4.2 years
1200
depth
1000
800
Over 4mm
600
Pit Count
400
200
0
0
0
3P
4P
No pit over 4mm depth
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Pit depth after 2.3 and 4.2 years service
COT 3P
Max. 2.6mm 2.3 years?Max. 2.5mm 4.2 years
COT 4P
Max. 3.1mm 2.3 years?Max. 3.1mm 4.2 years
Maximum pit depth did not change with time
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Pitting Corrosion Growth Termination
Depth at 2.3 and 4.2 years absolutely
proportional ? No change in pit depth
Pit growth stopped after COT cleaning and drying
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NSGP-1 Potential for Repair-free
NSGP-1 COT Cleaning ? Repair-free
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Summary of the NSGP-1
1)Confirmed excellent corrosion resistance
in actual VLCC 2) Potential for repair free for
whole ship life 3)Excellent mechanical
properties and weldability 4)No dependence on
condition of application
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Practical Advantages of the NSGP-1 for Ship
Owners

• By using NSGP-1 for COT of crude oil carriers,
• Great improvement in the safety and reliability
  of marine vessels and in the protection of the
  global environment
• Corrosion protective coating is not necessary, as
  do coating agents and volatile organic compounds.
• Repair free
• ?
• NYK decided to use the NSGP-1on all new
  VLCCs from now on

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What is going on at IMO?

• Draft SOLAS amendment on protection of COT of
  tankers
• accepted usage of alternative means (W.G.
  of DE51 08.2)

3 All cargo oil tanks of crude oil tankers shall
be .1 coated during the construction of the
ship in accordance with the Performance standard
for protective coatings for
cargo oil tanks of crude oil tankers, adopted by
the Maritime Safety Committee by resolution
. or .2 protected by alternative means of
corrosion protection, the effectiveness of
which shall be no less than the objectives
.... 4 The Administration may exempt a crude oil
tanker from the requirements of paragraph 3 of
this regulation to allow the use of novel
prototype alternatives to the coating system
specified in paragraph 3.1, .
NSGP-1 could be an alternative mean
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NSGP-1 Nippon Steels Green Protect -1
NYK LINE Hidehiko Sato hidehiko_sato_at_jp.nyklin
e.com Nippon Steel Corporation Tatsuro Nakai
nakai.tatsuroh_at_nsc.co.jp
Note NSGP is a registered trade mark or trade
mark of Nippon Steel Corporation in Japan and
other countries.