Co

ati

ng

s a

nd

Cath

od

ic P

rote

cti

on

ØC

P -

Ca

thodic

Pro

tection:

§basic

ele

ctr

ochem

ical pri

ncip

le

§basic

opera

tional re

co

mm

endations

ØE

lectr

ical re

sis

tance o

f coating a

nd d

egra

dation o

ver

tim

e

ØC

oating d

isbond

ment due to C

P a

nd o

ther

reasons

ØC

ath

odic

Pro

tection –

the u

ltim

ate

sa

feguard

?

ØP

erf

orm

ance o

f C

oatings b

ased o

n P

ure

Ho

mopoly

mer

Poly

iso

bute

ne

To

pic

s c

overe

d i

n t

his

pre

sen

tati

on

Intr

od

ucti

on

Coatings a

re a

pplie

d o

n b

uried a

nd im

mers

ed m

eta

llic p

ipelin

es in o

rder

to m

inim

ize t

he r

isk o

f corr

osio

n.

Cath

od

ic p

rote

cti

on

-V

+

Rs

oil

RP

ipe

I CP

CP

Pow

er

Supp

ly

Rem

ote

gro

und-

be

dw

ith

Anod

e

Sin

ce p

erf

ect

coatings d

o n

ot

exis

t, c

ath

odic

pro

tection is o

ften insta

lled t

o

act

as a

backup f

or

coating im

perf

ections a

nd d

am

ages.

Coating

dam

ag

e

Rc

oati

ng

I Des

ign

Cath

od

ic p

rote

cti

on

– h

ow

it

wo

rks (

1)

1.4

1.0

0.6

0.2

-0.2

-0.6

-1.0

-1.4

-1.8

1

4

7

10

13

Passiv

ity

Corr

osio

n

Imm

unity

Potential vs CSE (V)

pH

-valu

e

Pourb

aix

dia

gra

m o

f Ir

on (

Fe)

Reg

ion

of

inte

rest

for

Cath

od

ic P

rote

cti

on

:

•U

≈

as l

ow

as -

1.5

V

•p

H ≈

4 t

o 1

3

“What

happens if

you p

ut

a p

iece o

f bare

ste

el in

wate

r and a

pp

ly a

pote

ntial?

”

Cath

od

ic p

rote

cti

on

– h

ow

it

wo

rks (

2)

Passiv

ity

Imm

unity

Potential vs CSE (V)

pH

-valu

e

0.8

5V

CS

E

Pourb

aix

dia

gra

m -

Regio

n o

f in

tere

st

for

CP

Acti

vati

on

po

lari

zati

on

:

By s

hifting t

he p

ote

ntial

tow

ard

s n

egative v

alu

es,

inhib

itio

n o

f corr

osio

n

reaction o

f iron o

ccurs

Fe

Fe

2+ +

2e

-

-0.2

-0.6

-1.0

-1.4

4

7

10

13

Co

ncen

trati

on

p

ola

rizati

on

:

Main

tain

ing a

hig

h p

H a

nd

the f

orm

ation o

f a

passiv

ation layer

on t

he

surf

ace c

auses

suppre

ssio

n o

f th

e

corr

osio

n r

eactions.

(CeoC

or

confe

rence 2

014:

M.B

uechle

r, S

GK

, S

witzerland,)

Cath

od

ic p

rote

cti

on

- o

pera

tio

nal re

co

mm

en

dati

on

s (

1)

Po

lari

sati

on

po

ten

tial:

Many r

ecom

mendations e

xis

t, m

ain

ly d

ependin

g o

n o

pera

tional

conditio

ns s

uch a

s t

ype a

nd r

esis

tance o

f em

beddin

g (

soil,

wate

r).

NA

CE

SP

0169-2

013

– U

nderg

round o

r subm

erg

ed p

ipes:

Carb

on s

teel -0

.95 V

vs C

opper

Sulp

hate

Ele

ctr

ode (

CS

E)

ISO

15589-1

:2015 –

“On

-land”

pip

elin

es,

dependin

g o

n s

ubstr

ate

,

corr

osio

n p

ote

ntial, t

em

pera

ture

, and e

nvironm

enta

l conditio

ns,

e.g

.:

Carb

on s

teel (g

enera

l) ≥

-0.8

5 V

to -

1.2

0 V

vs C

SE

Carb

on s

teel, u

nder

MIC

conditio

ns ≥

-0.9

5 V

to -

1.2

0 V

vs C

SE

Galv

aniz

ed s

teel -1

.20 V

vs C

SE

Cath

od

ic p

rote

cti

on

- o

pera

tio

nal re

co

mm

en

dati

on

s (

2)

!.".#:$$$%&'&=()×*×+×, -/and$,-=0123 -'

Tota

l curr

ent

dem

and c

an b

e c

alc

ula

ted b

ased o

n c

oating b

reakdow

n f

acto

rs

(8.4

.2),

or

based o

n c

urr

ent

density v

alu

es f

or

coate

d p

ipes (

8.4

.3)

ISO

15589-1

:2015 –

Desig

n c

urr

en

t d

en

sit

y

I tot!

: !Tota

l curr

ent

dem

and (

mA

)

4D×L!:!

Pip

e s

urf

ace a

rea (

m²)

k!

:!C

ontingency f

acto

r due t

o p

ossib

le n

on

-uniform

curr

ent

dis

trib

ution a

long t

he p

ipelin

e.

Usually

k >

1.2

5

J c!

:!T

ypic

al desig

n c

urr

ent

density f

or

coate

d p

ipe

5E!

:!P

ote

ntial shift

due t

o C

P c

urr

ent

measure

d a

gain

st

a

rem

ote

refe

rence e

lectr

ode (

mV

)

r co*!

:!A

vera

ge c

oating r

esis

tance (

Ω.m

²)

* S

pecific

ele

ctr

ical in

sula

tion r

esis

tance R

s1

00 a

s d

escribed in

ØIS

O 2

1809-3

“F

ield

join

t coatings”

ØIS

O D

IS 2

1809-1

1 “

Coatings f

or

in-f

ield

applic

ation,

coating r

epairs a

nd

rehabili

tation.”

Cath

od

ic p

rote

cti

on

- o

pera

tio

nal re

co

mm

en

dati

on

s (

3)

ISO

15589-1

:2015 -

Curr

ent

densitie

s j

c f

or

pip

e c

oatings (

mA

/m²)

Pip

e c

oating

Optim

ized

desig

n

Conserv

ative

desig

n

3LP

E o

r 3LP

P

0.0

01 t

o 0

.02

0.0

5 t

o 0

.2

FB

E0.0

2 t

o 0

.2

0.4

to 0

.7

Coal ta

r or

Bitum

inous

0.2

to 0

.3

0.3

to 0

.8

Note

s:

ØF

igure

s b

ased o

n e

xperience f

rom

diffe

rent

opera

tors

ØO

ptim

ized d

esig

n:

optim

istic b

ut

realis

tic d

am

age c

onditio

ns,

shall

be u

sed f

or

the d

esig

n o

f galv

anic

anodes

ØC

onserv

ative d

esig

n:

pessim

istic d

am

age c

onditio

ns,

should

be

used f

or

the d

esig

n o

f im

pre

ssed c

urr

ent

syste

ms

ISO

15589-1

:2015 –

Desig

n c

urr

en

t d

en

sit

y

When h

isto

rical data

for

a c

ert

ain

type o

f coating is n

ot

availa

ble

,

Specific

Ele

ctr

ical In

sula

tion R

esis

tance R

s1

00 g

ives a

good indic

ation

for

initia

l curr

ent

density.

12

– P

oly

meric t

apes

14

– H

eat

shrinkable

mate

rials

15

– H

ot

applie

d m

icro

cry

sta

lline w

ax

16

– E

lasto

meric c

oatings

17

– F

usio

n B

onded E

poxy (

FB

E)

19

– H

ot

applie

d P

E/P

P (

flam

e s

pra

y, s

heets

,

tapes,

inje

ction m

ould

ed)

Cath

od

ic p

rote

cti

on

– c

oati

ng

resis

tan

ce (

1)

ISO

21809-3

:2016 –

Sp

ecif

ic E

lectr

ical

Insu

lati

on

Resis

tan

ce R

s1

00

* W

hen R

s7

0≤ 1

0 X

Rs

10

0 then R

s1

00

/R

s7

0≥ 0

.8

Requirem

ents

for

Rs

10

0 o

f field

join

t coatings (

Ω.m

²),

and d

erived

curr

ent

densitie

s

(ΔE

= 1

000 m

V)

Coating t

ype

Rs

10

0*

Calc

ula

ted

j c (

mA

/m²)

11A

/B -

Petr

ola

tum

and w

ax t

apes

18A

/B -

Liq

uid

epoxy,

Liq

uid

poly

ure

thane

18C

/D -

Fib

re-r

ein

forc

ed e

poxy a

nd v

inyle

ste

r

≥10E

+6

0.0

01

13A

/B -

Non-c

rysta

lline low

-vis

cosity p

oly

ole

fin

≥10E

+8

0.0

00 0

1

Cath

od

ic p

rote

cti

on

– c

oati

ng

resis

tan

ce (

2)

ISO

21809-3

:2016 –

Testi

ng

Rs

10

0

Coated pipe

R=

1M

Ω

2 m

V

DC

po

wer

su

pp

ly ≥

50V

Test vessel

Hig

h-o

hm

ic

mil

livo

lt m

ete

r

Cath

od

ic p

rote

cti

on

– c

oati

ng

resis

tan

ce (

3)

ISO

21809-3

:2016 –

Testi

ng

Rs

10

0

67=

89;;<

8>?972@AAA

×B

8>?972@AAA26

Rs

:S

pecific

ele

ctr

ical in

sula

tion r

esis

tance (

Ω.m

²)

Vapp

:A

pplie

d p

ote

ntial (V

)

Vm

eas

:M

easure

d v

oltage d

rop a

cro

ss r

esis

tor

(mV

)

A:

Effective c

oating a

rea s

ubje

cte

d t

o t

est (m

²)

R:

Resis

tor

valu

e (

Ω)

Cath

od

ic p

rote

cti

on

– c

oati

ng

resis

tan

ce (

4)

ISO

21809-3

:2016 –

Sp

ecif

ic E

lectr

ical

Insu

lati

on

Resis

tan

ce R

s1

00

Reco

mm

en

dati

on

s:

ØR

s1

00 m

eth

od g

ives indic

ation o

f in

itia

l th

eore

tical curr

ent

density

only

.

ØIt

does n

ot

pre

dic

t lo

ng t

erm

coating p

erf

orm

ance a

nd c

oating

bre

akdow

n o

ver

com

mon p

ipe life c

ycle

s.

ØIt

is r

ecom

mendable

to inclu

de a

n a

ccele

rate

d c

oating a

gein

g

test fo

llow

ed b

y r

esis

tance m

easure

ment.

ØIS

O21809-3

:2016 s

pecifie

s r

equirem

ents

for

few

types o

f coatings

only

.

ØIt

is r

ecom

mendable

to inclu

de R

s1

00 r

equirem

ents

for

oth

er

types o

f coatings a

lso.

Cath

od

ic p

rote

cti

on

- D

isb

on

dm

en

t o

f co

ati

ng

s (

1)

2H

2O

+ 2

e-→

2O

H- +

H2

(g)

2O

H-

H2

(g)

ØpH

rais

es t

o 1

0 –

12:

§C

hem

ical att

ack o

n a

dhesiv

e /

coating

§C

hange in c

om

positio

n

§Loss o

f essential pro

pert

ies lik

e a

dhesio

n

ØG

as f

orm

ation u

nder

edge o

f coating:

§Lifting o

f coating

Fe

2e

-

I CP

2H

2O

CP

curr

ent

has d

irect

path

wa

y t

o b

are

ste

el

Colo

ur

inte

nsity

indic

ate

s p

H g

radie

nt

Cath

od

ic p

rote

cti

on

- D

isb

on

dm

en

t o

f co

ati

ng

s (

2)

Fe

I CP

Co

ati

ng

Dis

bo

nd

men

t an

d L

ifti

ng

fro

m

su

bstr

ate

Coating d

isbondm

ent

pro

gre

sses w

ith t

ime

Ele

ctr

oly

te w

ith

hig

h p

H

is d

raw

n u

nd

ern

eath

dis

bo

nd

ed

co

ati

ng

“C

ath

od

ic D

isb

on

dm

en

t”

Cath

od

ic p

rote

cti

on

- D

isb

on

dm

en

t o

f co

ati

ng

s (

3)

Fe

I CP

Acti

vati

on

p

ola

rizati

on

Fe←

Fe

2+

+2e

-

Co

nvecti

on

blo

ckin

g, h

en

ce

co

ncen

trati

on

po

lari

zati

on

Fu

lly p

rote

cte

d d

esp

ite c

oati

ng

dis

bo

nd

men

t

Co

ati

ng

D

isb

on

dm

en

t

The c

ritical curr

ent

density in c

ase o

f convection b

lockin

g r

equire

d f

or

passiv

ation is 1

mA

/m²

bare

ste

el. (

CeoC

or

2014: M

. B

uechle

r, S

GK

, S

witzerland,)

Pro

tection o

f dis

bonded a

rea

Cath

od

ic d

isb

on

dm

en

t – F

ield

exp

eri

en

ce

Possib

le c

auses:

Induced m

echanic

al dam

age t

hat

was w

ell-

pro

tecte

d b

y C

P.

Cath

odic

dis

bondm

ent

over

a larg

e a

rea b

ut

no

co

rro

sio

n w

as f

ou

nd

Dis

bondm

ent

of

3LP

E p

lant

applie

d c

oating

Cath

od

ic d

isb

on

dm

en

t te

sti

ng

(1)

A p

ara

mount

perf

orm

ance p

ara

mete

r accord

ing t

o s

om

e …

Sta

nd

ard

Po

ten

tia

l (V

)D

efe

ct

ØTe

mp

.E

lec

tro

lyte

D

ura

tio

nR

eq

uir

em

en

t

AS

TM

-G8

-1.4

5 t

o -

1.5

5 v

s C

SE

1/4

”2

3oC

Tri

ple

sa

lt 1

)3

0d

2)

No

ne

(te

st

meth

od

on

ly)

AS

TM

-G4

2-1

.53

vs

CS

E a

t 6

0oC

-1

.46

vs

SC

E a

t 6

0oC

1/4

”M

ax

. 6

0oC

Tri

ple

sa

lt 1

)3

0d

2)

No

ne

(te

st

meth

od

on

ly)

AS

TM

-G9

5-3

.00

vs

CS

E

-3.0

7 v

s S

CE

1

/8”

23

oC

3%

NaC

l9

0d

No

ne

(te

st

meth

od

on

ly)

AS

43

52

Req

uir

ed

cu

rre

nt

3 m

A

Mo

nit

ori

ng

po

ten

tia

l vs

SC

E6

mm

22

.5oC

3%

NaC

l

28

dA

:≤ 1

0m

m

B:

≤ 1

5m

m

C:

≤ 2

0m

m

D,

E:

≥ 2

0m

m

65

oC

24

h / 2

8d

95

oC

24

h

CS

A Z

-24

5.3

0

(FC

4)

-1.5

vs

SC

E

1/4

”2

0oC

3

% N

aC

l2

8 d

≤ 1

2 m

m

Tm

ax

By a

gre

em

en

t

EN

12

068

-1.3

8 v

s A

g/A

gC

l/s

at

KC

l-1

.39

vs

Ag

/Ag

Cl/

3M

KC

l

-1.4

2 v

s S

CE

-1.5

0 v

s C

SE

6m

m

23

oC

3%

NaC

l2

8d

A,

B,

C(H

T)

≤ 2

0m

mC

30

≤ 1

0m

mC

50

≤ 1

5m

mT

ma

x. 5

0oC

By a

gre

em

en

t

ISO

21

80

9-3

typ

e 1

2

-1.2

6 v

s S

HE

-1.5

0 v

s S

CE

6

mm

2

3oC

3%

NaC

l2

8d

≤ 1

5m

m

Tm

ax

. 9

5oC

By a

gre

em

en

t

1) 1

% N

aC

l +

1%

Na

2S

O4 +

1%

Na

2C

O3

2) O

pti

on

all

y l

on

ge

r b

y a

gre

em

en

t

SC

E =

Sa

tura

ted

Calo

me

l E

lec

tro

de

CS

E =

Sa

tura

ted

Co

pp

er/

Co

pp

er

Su

lph

ate

Ele

ctr

od

e

SH

E =

Sta

nd

ard

Hyd

rog

en

Ele

ctr

od

e

Cath

od

ic d

isb

on

dm

en

t te

sti

ng

(2)

2O

H-

H2(g

)

2e

-

I cd

t

2H

2O

+ 2

e-→

2O

H- +

H2(g

)

An

od

e

Ref.

El.

C

hlo

rine g

as (

Cl 2

) is

form

ed a

t anode. T

his

substa

nce r

eacts

with

hydro

xyl-

ions t

o f

orm

hypochlo

rite

, w

hic

h is t

he

active s

ubsta

nce p

resent

in e

.g.

ble

ach

An

accele

rate

d t

est

for

resis

tan

ce t

o h

igh

pH

an

d t

o C

hlo

rin

e:

Chlo

rine a

nd H

ypochlo

rite

are

know

n f

or

havin

g s

trong o

xid

ative

pro

pert

ies t

o o

rganic

substa

nces.

Art

ific

ial

co

ati

ng

defe

ct

Ø

6m

m / ¼

”

Cath

od

ic d

isb

on

dm

en

t te

sti

ng

(3)

Som

e t

ypic

al te

st setu

ps

ISO

21

80

9-3

:2016

AS

TM

G8

AS

TM

G4

2

AS

TM

G9

5

AS

43

52 (

B)

Use o

f P

ote

ntiosta

t

recom

mended

Use o

f “isola

ted”

anode r

equired;

pre

vents

diffu

sio

n o

f

chlo

rine into

bulk

of

ele

ctr

oly

te

Cath

od

ic d

isb

on

dm

en

t te

sti

ng

(4)

Inspection o

f coating d

isbondm

ent

Cath

od

ic d

isb

on

dm

en

t te

sti

ng

(5)

DIN

30670:2

012 -

A d

iffe

ren

t sta

nd

po

int

for

PE

pla

nt

co

ati

ng

s

Sco

pe:

facto

ry-a

pplie

d 3

LP

E

one-

or

multi-la

yere

d s

inte

red P

E.

Fo

rew

ord

:D

isbondm

ent

of

dam

aged p

oly

eth

yle

ne c

oatings involv

es n

eit

her

an

in

cre

ased

ri

sk o

f co

rro

sio

n (

under-

rusting)

no

r an

in

cre

ase i

n t

he p

rote

cti

ve c

urr

en

t

den

sit

y r

eq

uir

em

en

t in

cath

odic

corr

osio

n p

rote

ction.

The c

ath

odic

dis

bondm

ent

test th

us d

oes n

ot

serv

e t

o e

valu

ate

the b

oundary

phase

reaction in t

he c

ase o

f dam

aged c

oatings,

whic

h is u

navoid

able

in p

ractice,

but

is

prim

arily

a m

eans o

f assessin

g t

he b

oundary

are

as b

etw

een t

he e

poxy r

esin

layer

and t

he s

teel substr

ate

.

This

test has t

here

fore

been s

pecifie

d h

ere

to e

valu

ate

surf

ace

pre

para

tion.

For

sin

gle

-layer

sin

tere

d p

oly

eth

yle

ne c

oatings,

it is d

ifficult t

o a

chie

ve t

he r

equired p

eel

str

ength

without

suitable

surf

ace p

repara

tion,

and s

o t

he c

ath

odic

dis

bondm

ent

test

is n

ot

required f

or

sin

gle

-layer

sin

tere

d p

oly

eth

yle

ne c

oatin

gs.

Cath

od

ic d

isb

on

dm

en

t te

sti

ng

(6)

Co

nclu

sio

ns a

nd

Reco

mm

en

dati

on

s:

Many t

est

meth

ods e

xis

t but

results c

annot

mutu

ally

be c

om

pare

d !

Harm

oniz

ation is h

ighly

recom

mendable

because t

here

is m

any v

ariation

in t

est

conditio

ns,

a.o

.:

ØR

efe

rence e

lectr

odes a

nd t

est

pote

ntials

ØTest dura

tions

ØTest te

mpera

ture

s

ØU

se o

f is

ola

ted a

nodes t

o p

revent

exposure

to c

hlo

rine

ØU

se o

f pote

ntiosta

t fo

r contr

ol and loggin

g o

f curr

ents

and p

ote

ntials

Many t

ypes o

f coating d

isbondm

ent

exis

t, c

ath

odic

dis

bondm

ent

is just

one o

f th

em

.

Oth

er

cau

ses o

f co

ati

ng

dis

bo

nd

men

t Labora

tory

tests

– a

dhesio

n a

fter

accele

rate

d a

gein

g b

y h

ot

wate

r im

mers

ion

3-l

ayer

Poly

pro

pyle

ne @

95°C

2-layer

Poly

eth

yle

ne @

60°C

Heat-

shrinkable

sle

eve @

80°C

FB

E @

95°C

Adhesio

n s

trength

•In

itia

l: 1

00%

•60 d

ays:

7%

•120 d

ays:

0%

Adhesio

n s

trength

•In

itia

l: 1

00%

•60 d

ays:

0%

•120 d

ays:

0%

Adhesio

n s

trength

•In

itia

l: 1

00%

•60 d

ays:

124%

•120 d

ays:

56%

Adhesio

n s

trength

•In

itia

l: 1

00%

•60 d

ays:

40%

•120 d

ays:

29%

Cath

od

ic P

rote

cti

on

- a

safe

gu

ard

in

all

cases

? (

1)

Many t

ypes o

f coating d

am

ages

Cath

od

ic P

rote

cti

on

- a

safe

gu

ard

in

all

cases?

(2)

Vary

ing e

nvironm

ents

Cath

od

ic P

rote

cti

on

- a

safe

gu

ard

in

all

cases?

(3)

Cath

od

ic P

rote

cti

on

is a

ris

k-b

ased

tech

no

log

y*

ØV

ariation in s

oil-

resis

tivity

ØD

C s

tray c

urr

ents

ØT

idal are

as

ØA

C c

urr

ent

corr

osio

n

ØA

dja

cent

str

uctu

res o

r obje

cts

ØS

ulp

hate

Reducin

g B

acte

ria

ØH

igh o

pera

tional te

mpera

ture

s

ØB

ackfill

void

s

*C

eoC

or

confe

rence 2

015: B

. M

art

in, B

rian M

art

in &

Associa

tes, A

ustr

alia

A c

oati

ng

th

at

pro

vid

es e

xcell

en

t lo

ng

term

co

rro

sio

n p

rote

cti

on

is h

igh

ly r

eco

mm

en

dab

le.

Sto

paq

Co

ati

ng

Syste

ms

C

onsis

ts o

f at

least

2m

ate

rials

with d

iffe

rent

functions:

•C

orr

osio

n p

revention:

Sto

paq W

rappin

gband b

ased o

n p

ure

hom

opoly

mer

Poly

isobute

ne (

PIB

)

•M

echanic

al pro

tection:

Sto

paq O

ute

rwra

p p

oly

meric t

ape,

heat

shrinkable

sle

eve,

etc

.

Pro

pert

ies o

f p

ure

ho

mo

po

lym

er

Po

lyis

ob

uty

len

e (

PIB

)

MM

range:

n=

180 -

1400

ØLiq

uid

with low

gla

ss t

ransitio

n

tem

pera

ture

of

-67°C

:

üC

old

flo

w p

ropert

ies,

beneficia

l fo

r

100%

covera

ge.

üLiq

uid

, th

ere

fore

unable

to b

uilt

-up

inte

rnal str

esses.

ØV

ery

low

perm

eabili

ty f

or

wate

r vapour

and o

xygen:

üB

eneficia

l fo

r corr

osio

n p

revention.

ØN

o s

ensitiv

e c

hem

ical gro

ups:

üG

ood c

hem

ical re

sis

tance.

üR

esis

tance t

o a

gein

g a

nd w

eath

ering.

ØA

dhesio

n b

ased o

n v

anderW

aals

forc

es:

üS

urf

ace p

repara

tion n

ot

critical fo

r pro

per

bondin

g

üH

igh t

ack a

nd e

xcelle

nt

adhesio

n t

o v

arious s

ubstr

ate

s lik

e s

teel, P

E,

PP,

FB

E,

de-r

uste

d s

teel, n

eopre

ne e

tc.

Self

-heali

ng

of

Co

ati

ng

s b

ased

on

pu

re h

om

op

oly

mer

PIB

(1)

P

1)

Tensio

nle

ss a

pplic

ation o

f

pure

hom

opoly

mer

PIB

based c

om

pound layer

2)

Applic

ation o

f P

oly

meric

Oute

rwra

p w

ith

tensio

n

Self

-heali

ng

of

Co

ati

ng

s b

ased

on

pu

re h

om

op

oly

mer

PIB

(2)

1.

Dam

age induced t

o the c

oating (

Ø 6

mm

)

2.

Fle

xib

le m

echanic

al O

ute

rwra

p e

xert

s p

ressure

to the p

ure

hom

opoly

mer

PIB

based c

om

pound layer

3.

Com

pound f

low

s t

ow

ard

s t

he d

am

age a

nd s

eals

the s

teel fr

om

the

environm

ent.

When s

elf-h

eale

d,

it s

tops f

low

ing.

Self

-heali

ng

of

Co

ati

ng

s b

ased

on

pu

re h

om

op

oly

mer

PIB

(3)

CD

-test

of

Co

ati

ng

s b

ased

on

pu

re h

om

op

oly

mer

PIB

Cath

od

ic d

isb

on

dm

en

t re

sis

tan

ce a

cc.

ISO

21809-3

:2016

•@

+ 2

3OC

and +

70

OC

(=T

max)

for

28 d

ays @

-1500 m

V

Cath

od

ic d

isb

on

dm

en

t re

sis

tan

ce a

cc. A

ST

M G

42:

•@

+ 6

5OC

for

90 d

ays @

-3000

mV

Resu

lts o

f all

tests

:

•D

isbondm

ent

0 m

m (

or

actu

ally

-3 m

m)

•N

o h

olid

ays

•S

elf-h

ealin

g c

om

ple

ted w

ithin

24 h

ours

.

Acce

lera

ted

ag

ein

g t

es

t C

oati

ng

s b

as

ed

on

pu

re h

om

op

oly

me

r P

IB

Peel

tests

aft

er

Th

erm

al A

gein

g a

nd

H

ot

Wate

r Im

mers

ion

fo

r 100 d

ays @

T

max+

20°C

No c

hange in c

oating p

erf

orm

ance

aft

er

accele

rate

d a

gein

g t

ests

:

üP

eel str

ength

valu

es ≥

0.2

N/m

m @

23°C

üP

eel str

ength

valu

es ≥

0.0

2 N

/mm

@T

max

üC

ohesiv

e f

ailu

re

üC

overa

ge ≥

99%

Resis

tan

ce R

s1

00 o

f p

ure

ho

mo

po

lym

er

PIB

-based

co

ati

ng

Rs

70: 1.6

E+

10 Ω

.m²

Rs

10

0: 8.1

E+

09 Ω

.m²

Co

nclu

sio

ns

ØC

orr

osio

n o

f pip

elin

es is a

ris

k, cath

odic

dis

bondm

ent

of

coatin

gs is n

ot!

ØA

sset

ow

ners

should

focus m

ore

on c

oatings t

hat

have g

ood long t

erm

perf

orm

ance p

ropert

ies w

hic

h c

an b

e e

valu

ate

d b

y e

.g.

accele

rate

d a

gein

g

tests

.

ØC

oatings b

ased o

n p

ure

hom

opoly

mer

Poly

isobute

ne m

eet

or

even e

xceed

exis

ting p

erf

orm

ance r

equirem

ents

:

ØH

igh

Specific

Ele

ctr

ical In

sula

tion R

esis

tance

ØS

elf-h

ealin

g o

f sm

all

co

ating d

efe

cts

ØC

ath

odic

Dis

bondm

ent te

sts

result in 0

mm

dis

bondm

ent and n

o

holid

ays

ØE

xce

llent lo

ng term

re

sis

tance to a

gein

g in d

ry a

nd w

et co

nd

itio

ns

at m

axim

um

desin

g tem

pera

ture