18 JUN 2010코렐테크놀로지㈜ 이선엽코렐테크놀로지㈜ 이선엽

금속이 주변환경과의 반응으로 산화되어 원래의 성질을 잃는 현상 양극: M → Mn+ + ne-

음극: O2 + 2H2O + 4e- → 4OH-2 2

부식의 4대 요인 양극 (anode)양극 (anode) 음극 (cathodic) 전자전도체 (금속) 이온전도체 (전해질) 이온전도체 (전해질)

(+) 폐쇄회로

Other reduction reaction In an acid solution OH2e4H4O 22

In a neutral or base solution OH4e4OH2O 22

T diff t t lOne metal only

A

Two different metal

Cathodic site

Anode Cathode

A

Anodic site

Pte-

e-

Gas explosion caused by charged soil (crater size: 15 m x 34 m) due to microbial corrosion of gas pipeline (Carlsbed, New Mexico, USA, Aug. 19, 2000)

Source: National Transportation Safety Board (USA) www.ntsb.gov

Highway Bridges $8.3

Cost of corrosion (1998, USA)

Gas and Liquid Transm. Pipelines

Waterways and Ports

Hazardous Materials Storage

Air Ports

$7.0

$0.3

$7.0

-

Total 276 billion $ !!3.1% of GDP

Railroads

Gas Distribution

Electrical Utilities

-

$5.0

$6 9

Drinking Water and Sewer System $36.0

Electrical Utilities

Telecommunication

Motor Vehicles

Ships

Aircraft

$6.9

-

$23.4

$2.7

$2 2Aircraft

Railroad Cars

Hazardous Materials Transport

Oil and Gas Expl. And Production

Mining

$2.2

$0.5

$0.9

$1.4

$0.1

Corrosion Cost and Preventive Strategies in the United States, G.H. Koch, M.P.H. Brongers, N.G. Thompson, Y.P. Virmani and J.H. Payer, FHWA-RD-01-156, Office of Infrastructure Research and Development F d l Hi h Ad i i t ti D t t f T t ti 2003

g

Petroleum Refining

Chem., Petrochem., Parm.

Pulp and Paper

Agricultural

$3.7

$1.7

$6.0

$1.1

$Federal Highway Administration, Department of Transportation, 2003

g

Food Processing

Electronics

Home Appliances

Defense

$2.1

-

$1.5

$20.0

Nuclear Waste Storage $0.1

Cost of Corrosion Per Analyzed Economic Sector, ($ x billion)

$10 $20 $30$0 $40

8

Most common Corrosive environment evenly distributed over entire metal surface Metal: metallurgically and compositionally uniform On the basis of tonnage waste the most important forms of corrosionOn the basis of tonnage waste, the most important forms of corrosion Most readily detectable (visual) and preventable (alloying)

Atmospheric corrosion (rusting)

Corrosion in acid solutions

TABLE Galvanic Series in Seawater (or Fig 6 1)TABLE. Galvanic Series in Seawater (or Fig. 6.1)

The galvanic seriesThe galvanic seriesThe galvanic series

Ordered by observed behavior in service Allows for corrosion products

The galvanic series

Ordered by observed behavior in service Allows for corrosion products Can be defined for alloys Different for every environment

Note that some alloys can appear twice acc

Can be defined for alloys Different for every environment

Note that some alloys can appear twice acc Note that some alloys can appear twice according to whether they are active or passive.

Note that some alloys can appear twice according to whether they are active or passive.

Cathodic protection (CP), sacrificial anode protection Galvanized steels; Zn is anodic to steel, act as a sacrificial metal

water-line corrosion

Crevice corrosion of Ti flange in hot seawater Crevice corrosion of SS

Crevice corrosion of socket weld at gap formed between type 304L pipeAnd type 316L valveAnd type 316L valve

Chloride pitting of Chloride pitting of stainless steel

due to soldering flux contamination

Pitting of exterior of lead cable sheath due to stray current

Carbon steelPittiPitting

underground

Pitting of Aluminum air duct due to salt contamination

Pitting of Inconel in Brine

Sensitization of Stainless Steel or Weld Decay

When grain boundary Cr carbide precipitation has occurred, the stainless steel is said to be sensitized.

Sensitization frequently occurs in the heat-affected zone (HAZ) during welding, and the resultant corrosion is called Weld decay.

Fig. 1.16. Erosion-Corrosion of a 316L SS flange and pipe(This pump takes its suction about 6m below the surface of the Persian Gulf)

IGSCC of an Inconel heat exchanger tube (500X) Chloride SCC of S31603 (316L) chemical processing pipingt It b h t i d b th lti b h dsystem. It can be characterized by the multi-branched

“lightning bolt” TG crack pattern (300X)

Caustic SCC in a 304L SS pipe in methanol reforming service – oxalic acid etch (50X)

Also called: hydrogen induced corrosion (HIC) Involves the ingress of hydrogen into the metal causing Reduced ductility and load-bearing capacity

Subsequent cracking and

Catastrophic brittle failures at stresses below the yield stress of susceptible ma Catastrophic brittle failures at stresses below the yield stress of susceptible materials

Most vulnerable are high-strength steels, titanium alloys and aluminum alloys

Alloying to resist corrosion (SS, cupronickel, etc.) Metallic coatings (galvanizing)

O i ti ( i t li i ) Organic coatings (paint, lining) Electrochemical protection Cathodic protection Cathodic protection

Anodic protection Corrosion inhibitors Automotive cooling systems, cooling towers, boilers, etc.

23

MATERIAL AND SERVICESRANGE AVERAGE COST

($ x billion) ($ x billion) (%)($ b o ) ($ b o ) (%)

Protective CoatingsOrganic CoatingsMetallic Coatings

33.5-167.51 4

100.51 4

86.71 2Metallic Coatings 1.4 1.4 1.2

Metals & Alloys 7.7 7.7 6.6Corrosion Inhibitors 1.1 1.1 1.0Polymers 1 8 1 8 1 6Polymers 1.8 1.8 1.6(Anodic) Cathodic Protection 1.97-2.46 2.22 1.9Services 1.2 1.2 1.0R h & D l t 0 020 0 02 <0 1Research & Development 0.020 0.02 <0.1Education & Training 0.01 0.01 <0.1

TOTAL $48.7-$183.19 $115.95 100%

Resistance to chemical environment, moistureResistance to chemical environment, moisture

H Ch i l dd d t th ti t hi d ti Have Chemicals added to the coating to hinders reactions. Lead & chromate inhibitive.

U ll t i Z d t th d i t i t Usually contain Zn dust as the predominant pigment Might be a sacrificial metal applied by hot-dip galvanizing or spray metallizing

28

Page x of y 29

An inhibitor is a chemical substance that, when added in small concentration to an environment, effectively decreases the corrosion rate. A minimum conc. of inhibitor must be present to maintain the inhibiting surface film. Thus, good circulation and the absence of any stagnant areas are necessary to maintain the required level of inhibitor concentration.An addition of inhibitors reduces icorr by increasing the Tafel slope and/or by reducing the exchange current density.

E E

A. Adsorption-type inhibitors O i d hi h d b th t l f d t l di l ti d d ti ti T i l

Anodic inhibitor Cathodic inhibitorlog i log i

Organic compounds which adsorb on the metal surface and suppress metal dissolution and reduction reactions. Typical of this class of inhibitors are the organic amines.

B. Hydrogen evolution poisonsThe susbstances such as As, Sb, P, and S retard hydrogen recombination reaction, thereby reducing corrosion rate of a metal in acid solutions.

C ScavengersC. ScavengersThese substances act by removing corrosive species from solution :Sodium sulfite : 2Na2SO3 + O2(sol.) 2Na2SO4Hydrazine : N2H4 + O2 N2 + 2H2O

D. Oxidizers or passivators- effective only in metals showing active/passive transition.: CrO4

2- , NO2-, MoO4

2- , WO42- , and ferric salt

CURRENTCURRENT

ANODEANODE

PowerSourceSource

+-

TT

CU

RCU

RCU

RREN

TCU

RREN

T

RREN

TRREN

T

ANODEANODE

5835.234.23125 4

100

3125.4

10

11

부식

속도

11

상대

부

0 04

0.1

0.04

0.018

0.01

-1000 -800 -600 -400 -200 0 200

전위 (mV/CSE)

Seawater is highly corrosive to mild steel (3.4% salt)

Species Concentration (mg/L)

Cl- 19,000

Na+ 10,700

Mg+2 1,300

Ca+2 400Ca+2 400

SO4-2 2,750

HCO3- 150HCO3 150

pH 8.0

Temperature 25oCp

Pressure 1 atm.

3.4% Salt (nearly constant) + slightly alkaline, pH 8: good electrolyte

l i i & i ican cause galvanic corrosion & service corrosion.

Corrosion is affected by O2 content, velocity, temperature and

biological organisms.

45

Sea water is a highly corrosive electrolyte towards mild steel. This ship has suffered severe damage in the areas which are most buffeted by waves, where the protective coating of paint has been largely removed by mechanical

actionaction.

Corrosion of ballast water tank

Calcareous deposit reduces the demand for current:

C l d it d th ff ti th di fCalcareous deposits reduce the effective cathodic surface area thereby lowering demand for current. The calcareous deposit is formed when MgOH and CaCOcalcareous deposit is formed when MgOH2 and CaCO3

salts precipitate on the cathode (steel surface).

The following changes the composition and quality of the calcareous layer:

t d it• current density• temperature• pressure• pressure• seawater quality• flow velocityy

3222 COHOHCO 3222

HCOHCOH 332 HCOHCOH

233 COHHCO

pH 변화에 버퍼링 기능 (pH 증가시 우측으로 진행)

H에 따라 이온종별 분율이 결정됨 pH에 따라 이온종별 분율이 결정됨

CO3–2 + Ca+2 -> CaCO3

M +2 OH¯ M (OH) Mg+2 + OH ->Mg(OH)2

Upper section atmospheric (C5 M)Upper section – atmospheric (C5-M)blades, turbine, housings & structure(0.08 – 0.2 mm/y), UV

Lower section – splash / tidaltower structure(0 2 – 0 5 mm/y) UV erosion(0.2 – 0.5 mm/y), UV, erosion

Bottom section– tidal/immersed/buried (Im 2) ( )tower structure(0.1 – 0.2 mm/y), fouling

Splash zone is the most critical

Protective coatings are used to control atmospheric, splash zone and underwater exposed surfaces.

Splash zone systems are subsets of protective coatings designed to withstand the more severe conditions of the splash zoneto withstand the more severe conditions of the splash zone.

Cathodic protection is used alone and in conjunction with protective coatings and splash zone systems to protect immersed surfaces.

57

Coastal / offshore areas with high salinity

sea or brackish water

Generic 15 year maintenance free systems

C5 Category Im-2 Category

3 6 t EP PU 1 2 t f l t f EP

with high salinity or brackish water

3-6 coats EP + PUTotal 300-500 microns

1-2 coats of solvent free EPTotal 800 microns

3-5 coats Zinc silicate + EP + PU 2-3 coats high solids EPTotal 300-400 microns Total 800 microns

1-2 coats solvent free EPTotal 800 microns

2 coats glass flake EPTotal 1000 microns

Area Coating Types Coating System

Atmospheric Zone 1: Zinc-rich primer Min. 320 um (dft) in min. 3 p p2: Epoxy3: UV durable topcoat (e.g., PU)

( )coats.

Splash Zone Epoxy or polyester Min 600 um (dft) in min. 2 coats

Immersion Zone Epoxy Min. 450 m (dft) in min. 2 coats.

Conventional Coatings Underwater-Curing Epoxy (UCE)

U idi ti l C it S t Unidirectional Composite Systems Wax-Based Composites (WBC) Silicone Gel-Based Composites (SGBC) Silicone Gel Based Composites (SGBC) Concrete Composite System (CC) Alloy Sheathing

62

Sacrificial (galvanic) anode Al (+In+Zn)

Zn

BASIC DESIGN

1. Pipeline Strength Design1. Pipeline Strength Design

Offshore Pipeline Wall Thickness 14.3/15.9 mm

Onshore Pipeline Wall Thickness 15.9/25.4 mmp

Buckle Arrestor Wall Thickness 21/24 mm

2. Corrosion Protection Design

Internal Epoxy coating for 36” line pipe.

FBE or 3-Layer PE external coating.

Installation of Sacrifial Aluminum Anodes for Offshore Pipeline.

Impressed Current CP (ICCP) system for Onshore Pipeline.

65

Trailing Wire

Spooling Dispenser

Platform

Spooling Dispenser

Survey VesselTrailing Wire

Attached to platform riser

Tow fish with Ag/AgCl HalfCell attached

Pipeline

SACP ICCP

Aluminum anodes mounted on a steel jacket structure Aluminum anodes mounted on a steel jacket structure

Protective coating + SACP

Protective coating + ICCP

Primary Shield 선체에 부착된 양극 바로 밑/옆 Fiberglass 또는 thermoplastic sheetg 는 p

양극으로부터 30-60cm

Secondary shield Epoxy 또는 mastic coatingEpoxy 또는 mastic coating

90-120cm

Shield의 손상은 Shield의 손상은 양극 인근의 과방식 과량의 수소발생으로 인한 코팅 박리 수소취화 등 초래 수소취화 등 초래

Spread MooredTarret Moored

Regulatory requirements Economics

M t l t b t t d Metal to be protected Service requirements Total current requirements Total current requirements Variation in environment Protective coatings Electrical shielding Maintenance Stray current effect Temperature

Wi d bl Wire and cable

Design parameter Typical Value

Seawater Resistivity 20 – 25 ohm-cm

Saline Mud 100 – 150 ohm-cm

Anode open circuit potential - buried

-1.05 V (Ag/AgCl)

Anode open circuit potential seawater

-0.95 V (Ag/AgCl)potential - seawater

Anode Consumption 1280 A hours/ pound

Anode Utilization Factor 0.80

Coating Breakdown Factor (FBE)

0.5% to 1.0% (initial)10% (after 30 years)

Insulation Breakdown Factor

0.5% to 1.0% (initial)3% (after 30 years)Factor 3% (after 30 years)

Neoprene Breakdown factor

0.5% to 1.0% (initial)5% (after 30 years)

Design current density for bare steel in seawater

12mA/ft2 (initial)7mA/ft2 (after polarization)

83

bare steel in seawater 7mA/ft2 (after polarization)

Design current density in sand or mud

2mA/ft2 (initial and after polarization)

Approach pp

1. Determine the total surface areas in seawater and mud zones which are to receive cathodic protection.

2. Calculate the start-up (initial) and maintenance current

required to protect the structure. 3 C l l t th i i i ht f d t i l i d f3. Calculate the minimum weight of anode material required for a

20-year service life. 4. Estimate effective anode to structure resistances. 5. Determine number and size of anodes required.

IReq =Idesign*Apipe*FCoating/1000 (1)Where:

I i th t t l t d d (A )IReq is the total current demand (Amps)Idesign is the design current densityA i is the total area of the pipelineApipe is the total area of the pipelineFCoating is the coating breakdown factor

4/16/2004 85

total anode weight required is then:

W (I * 8760 h / * t d lif ) / (C ti t * Wanodes = (Ireq * 8760 hr/year * expected life) / (Consumption rate * efficiency) (2)

Where: Wanodes is the total anode weight need to provide the current requirementIreq is the required current calculated in equation (1).

86

The number of anodes then is calculated as:

Ntotal = Wanodes/ W bracelet (3)

Where: Ntotal is the total number of bracelet anodes requires

Wanodes is the total weight calculated in equation (2).

W bracelet is the weight of each individual bracelet

4/16/2004 87

NACE Standard RP0176, Corrosion Control of Steel Fixed Offshore Platforms Associated with Petroleum, is the most common criterion f d t i i h th t t i i i d t th di for determining whether a structure is receiving adequate cathodic protection.

A negative (cathodic) voltage of at least –0.800 volts measured between the platform surface and a silver-silver chloride (Ag/AgCl) reference electrode contacting the water.

SACP ICCP

Structures Structures Similar to rigs, platforms and ships

Difference Unmanned Difficult to monitor/assess

RequirementsLong term performanceLong term performanceSuitable for fabrication processSuitable for range of environmentEase of repairEase of repair

NeedsCare in selectionQuality application

Upper section atmospheric (C5 M)Upper section – atmospheric (C5-M)blades, turbine, housings & structure(0.08 – 0.2 mm/y), UVCoating - durable, anti-corrosiveCoating durable, anti corrosive

Lower section – splash / tidaltower structure(0 2 – 0 5 mm/y) UV erosion(0.2 – 0.5 mm/y), UV, erosionCoating - durable, anti-corrosive

Bottom section– tidal/immersed/buried (Im 2) ( )tower structure(0.1 – 0.2 mm/y), foulingCoating - anti-corrosive, anti-fouling

Splash zone is the most critical

Cost Problem     Access to repair the coated s rface Cost Problem     Access to repair the coated surface 

S i  diffi l      & di lStaging difficult to erect & dismantle

Series of blasting & coating cellscells

Auto blasting / more consistent Rz and surface cleanliness

Some robot painting / internals Two component spray

equipment Dust free environment Climate & temperature Climate & temperature

regulation Relative Humidity controly

Photo  Muehlhan GmbH

Spray application epoxy / p/urethane multi llayersystems or topcoats

Photo  MuehlhanGmbH

Thermal sprayingThermal sprayingZn / Al alloy

metallization PhotoMuehlhanGmbH

Finish painting  internal areas

Photo  MuehlhanGmbH

Coating performance failures can occur because of one or more of the following:

D i Design

Product specification/selection

Product qualityq y

Management processes

Preparation/application

Maintenance Maintenance

Repairs

Climate/environmental control

Worker skill

Bad spray application Bad spray application

Sharp edges Photos    ABS, Houston

Stress cracking in dry film

sagging

undercutting

holiday

chalking discoloration

DisbondingBlistering

Metallization has now achieved 30 – 40 years low maintenance protection on offshore oil & gas structures

The cost and application speed for systems which include this process The cost and application speed for systems which include this processare now close to or the same as for multi layer organic coating systems

The reasons are a combination of New alloy materialsNew alloy materialsNew technology spray equipmentContractors improved ability to control the application environment

The current trend in Europe is tothermally spray Zn / Al (first coat) 60 – 100 mic dft+ sealer coat+ 2 x EP topcoats

Full exterior surface and internally 6-8 m up from bottom

UK target 202015% of energy from renewables

UK Round 3  Wind farm zones

Estimated that the UK has 33% wind resources in Europe

Offshore to be primary expansion zone. Wind is more constant and predictablep

Jan 2010 UK govt awards Round 3 wind g

farm zones / 9 successful bidders

£75bn programme for offshore Source: BWEA 

wind farm projects

MW Capacity 2010 ( Feb ) 2015 2020

Operational 688p

Under construction & planned

6,000

Zones awarded 33,000

Number of turbine 228 2 000 ± 11 000

towers ( est )228 2,000 ± 11,000

Total Operational Capacity 10 year plan 40,000 MWSource RenewableUK

Largest Offshore Capacity Plan in Europe

This is a major growth business sector.

Painting Offshore Wind Towers

Typical 3 MW Tower structure External m2

Internal m2 Totalm2

Painting area per tower 1250 1250 2500Painting area per tower 1250 1250 2500

Painting cost per towerg p

EP / PU multi layer @ € 5 / m2 € 6250 € 6250 € 12,500

Total cost Paint + Application € 31,250 € 31,250 € 60 – 70,000

up to € 25 / m2 * per tower

* Source JPCL / Muhlberg March 2010

Typical Wind Tower Structure

Installation cost per MW € 3.3 mill

Installation cost per tower / 3MW € 10 mill

Painting cost ( P+A ) per tower € 60 – 70,000

Paint + Application as % tower installation cost 0.6 – 0.7%

Factory painting + site erection painting ˂ less than 1% of installed costFactory painting + site erection painting ˂ less than 1% of installed cost

Tower structures 2010 ( Feb ) 2015 2020

Overview:    Painting areas & costs( )

No. of Tower structures 228 2,000 11,000

P i ti Painting areas

2500 m2 per 100m tower 0.57 mill m2 5 mill m2 27.5 mill m2

Painting costsPainting costs

Paint + Application€ 60 – 70,000 per tower

€14-16 mill €120-140 mill € 660-770 mill

If the build specification fails to performfailure repetition can multiply by the number of towers in the fieldf p p y y f f

Tower structures 2010 ( Feb ) 2015 2020

No of Tower structures 228 2 000 11 000No. of Tower structures 228 2,000 11,000

Total Painting area

2500 m2 per 100m tower 0.57 mill m2 5 mill m2 27.5 mill m2p

Total Painting cost

Paint + Application €14-16 mill €120-140 mill € 660-770 mill€ 60 – 70,000 per tower

Assume 3% area failure 17,100 m2 150,000 m2 825,000 m2

Offshore repair cost Offshore repair cost up to €1000/ m2 € 17 mill € 150 mill € 825 mill

To repair only 3% area failure To repair only 3% area failure could cost more than the total initial cost of painting

To improve application efficiency and tolerance, possibly of existing basic technologies.T d l i h tl t bl d d bl h i t i hi To develop new inherently more stable and durable chemistries, which meet all application requirements and give longer lifetimes.

To develop coating systems that provide benefits to the wind tower f To develop coating systems that provide benefits to the wind tower fabricator, e.g., speed of cure (steel through put), lower VOC (solvent) emissions

Standard/Specification ISO 20340

O ti 1▪ Option 1▪ 72 hours Salt spray 5% NaCl pH 7 (ISO 7253)

▪ 24 hours Dry out at -20°C

▪ 72 hours Condensation/UV (ASTM G53)

▪ 4 hours UV at 60ºC, 4 hours condensation at 50ºC

▪ ISO 20340 Cyclic Testing: Option 2▪ 72 hours Salt spray 5% NaCl pH 7 (ISO 7253)

▪ 24 hours Dry out at +23 °C

▪ 72 hours Condensation/UV (ASTM G53)( )

▪ 4 hours UV at 60ºC, 4 hours condensation at 50ºC

NORSOK M501

The submerged area (Monopod Type) This can be protected by the application of a coating of two-part epoxy

compound being applied at the construction yardcompound, being applied at the construction yard. A method of cathodic protection using zinc anodes should also be used to

compliment the epoxy coating.The anodes can be either fitted at the construction phase or an The anodes can be either fitted at the construction phase or an underwater sledge arrangement used. Both methods have their merits, the onshore fixing of the anodes to the structure being quicker and more economical but difficult to replace under watereconomical, but difficult to replace under water.

An underwater sledge consists of a frame which contains numerous anodes welded into it. The frame is then positioned close to the support on the seabed and connected to the structure by heavy copper wire cables This method and connected to the structure by heavy copper wire cables. This method allows for easy replacement of anodes but is expensive due to its installation to the location and, connection to the structure which requires underwater welding by diversby divers.

LIFT TRIPOD JACKET

Elevation (M)Areas

LIFT TRIPOD JACKET

0

Elevation (M)

Water Line

Areassq. meters

350205

-30806

318

1118-60

90

423

1849-90

-120

646

2167

-150

Mud Line

2167

1055

1971

1572 Mud Line1572

5005 MudSix Wells

Elevation AreaRelative Fraction of

Number of Anodes

Area

MetersSq. Meters

0 to –14 350 0.028 8

–14 205 0.016 4

–14 to –38 806 0.065 18

–38 318 0.025 7

–38 to –69 1118 0.090 2538 to 69 1118 0.090 25

–69 423 0.034 9

–69 to –105 1849 0.148 41

–105 646 0.052 14

–105 to –143 2167 0.174 48

–143 1055 0.085 24143 1055 0.085 24

–143 to –160 1971 0.158 44

–160 1572 0.126 35 + 6 = 41

Totals 12,480 1.000 283

경험에 의존한 방식설계 전류밀도

양 배치 양극 배치 등

보수적인 관점에서 설계가 이루어질 수 밖에 없음 보수적인 관점에서 설계가 이루어질 수 밖에 없음

과방식/미방식 문제 부식 피복 박리

Coatings Offshore wind tower의 경우 주기적으로 정박(dry docking)하여 유지보수

를 실시하는 선박이나 인력이 상주하여 유지보수가 가능한 플랫폼를 실시하는 선박이나, 인력이 상주하여 유지보수가 가능한 플랫폼과 비교할 때 시간/비용 측면에서 유지보수가 쉽지 않으므로 장수명, 고성능의 코팅재가 필요

CPCP 경험적인 방식설계로 국부적인 과방식/미방식 우려 방식전류밀도 과방식에 의한 코팅박리

기술개발기술개발 수치해석에 의한 전기방식설계 검증 내구성/작업성이 좋은 코팅재의 개발/신뢰성 평가

원격감시의 적용가능성 원격감시의 적용가능성

syli@correltech.com