TRizk-DCandACInterference-NACE.ppt

7/17/2019 TRizk-DCandACInterference-NACE.ppt

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EMS 2008

Control of DC and ACInterference on Pipelines

Tony G. Rizk, P.E. Nigel Strike

ice President !estern DirectorE"S #SA Inc. E"S #SA Inc.$o%ston, Te&as $o%ston, Te&as'()*++*'- '()*++*'-trizk/e0sglo1al.net nstrike/e0sglo1al.net
mailto:[email protected]:[email protected]


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EMS 2008 2

C2RR2SI2N

AND

CAT$2DIC PR2TECTI2N


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EMS 2008 3

3asic Corrosion "ec4anis0

Steel

Copper

Water

e-

e-

e-

e-

e- e-

e-

Anode (corrodes)

Electrolyte

(water, soil,mud, etc.)Cathode (protected)

Metallic Path

In typical soils, atAnode:

Iron goes into solution and combines with ions

in the electrolyte to orm corrosion !eposits

In typical soils, at Cathode:

Electrons consumed by

water"o#ygen $ protecti%e ilm

orms

e-

e-

e-

Corrosion

!eposits

Corrosion Current(Con%entional Current &low)


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EMS 2008 4

3asic Cat4odic Protection "ec4anis0

Steel

Magnesium

Copper

Anode

(corrodes)

Electrolyte

(water, soil,mud, etc.)

Cathodes

(protected)

Metallic Path

e-e-

e-e-

e-

e-

e- e-

e-e-


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EMS 2008 5

Cat4odic Protection 5 Gal6anic Syste0

Pipeline Pipeline

Cathodic Protection Current from Anode Groundbed

Magnesium Anode

Cathodic Protection Test Station

Cat4odic Protection is t4e application of protecti6e

c%rrent fro0 anodes onto t4e pipeline, forcing t4e

pipeline to 1eco0e cat4odic.


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EMS 2008 6

Cat4odic Protection 5 I0pressed C%rrent Syste0

Pipeline Pipeline

Cathodic Protection Current from Anode Groundbed

Cathodic Protection Anode Ground bed

Rectifier

'


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3asic Pipe*to*Soil Potential "eas%re0ent

Pipeline

Polarization film

Negative

+

_

V DC-1.150

Copper-Copper

Sulfate

Reference

Electrode

igh

!mpedance

"oltmeter

#Miller $C-%

Pictured&

Area ofPipe

detected

b'

electrode


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DC STRA7 C#RRENT INTER8ERENCE


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DC Stray C%rrent Interference

Stray current interference occurs when DC currenttrae!s a!on" a non#inten$e$ %ath&

'here DC stray current is receie$ (y a structure)the area (eco*es catho$ic an$ "enera!!y) no

corrosion occurs

'here DC stray current e+its the structure to

return to its source) corrosion occurs an$$e%en$in" on *a"nitu$e of stray current) can !ea$

to acce!erate$ corrosion fai!ures&


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-sin" .ara$ay/s aw) wei"ht !oss is $irect!y

%ro%ortiona! to current $ischar"e an$ ti*e 1 Stee! is

consu*e$ at 2, !(sa*%#year

E+a*%!e ,#inch $ia*eter cone sha%e$ %it in 0&500

thic stee! wou!$ wei"hs 0&04 %oun$s&

ne a*%ere of DC current $ischar"in" fro* a ,#inch

$ia*eter coatin" ho!i$ay wou!$ cause a throu"h wa!!) cone

sha%e$ %it to occur in 0&00,9 years or ,6 hours&

Stray current corrosion can (e a serious %ro(!e*&

DC Stray C%rrent Interference


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So%rces of DC Stray C%rrents

Static DC Currents: .orei"n Catho$ic rotection Syste*s

Dynamic DC Currents:

DC :raction ower Syste*s :ransit) eo%!e Moers)

Minin" :rans%ort Syste*s

;eturn

'e!$in" E?ui%*ent with =*%ro%er @roun$ @eo*a"netic A:e!!uricB Earth Currents


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EMS 2008 ,2

Corrosion Ca%sed 1y Stray C%rrent

CompanyPipeline

ForeignP

ipeline

Rectifier'

Anode (ed

Area of Current Pic)up *Area of Current Pic)up *

CathodicCathodic

Area of CurrentArea of Current

+ischarge+ischarge** A,+!CA,+!C


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EMS 2008 ,3

Testing and Identifying DC Stray C%rrent

otentia! *easure*ents AC!ose =ntera! SureysB arety%ica!!y use$ to i$entify stray current areas&

.*+

Pipe'to'-oilP

otential Current Picup

Current !ischarged/ac to -ource $ Metal

0oss (i Polari1ed Potential morenegati%e than '*+ m, controlling

reaction is the 2#idation o 23'4 no

metal loss)

0ine CausingIntererence

0ine /eingInterered 5ith

atin" 45 or 80 a*%s C

Solid State Decoupler (SSD)

60 ; .au!t Current K , cyc!e 2),00F 5)300F 6)500F 8)800

K 3 cyc!es ,)600F 4)500F 5)000F 6)800

i"htnin" Sur"e Current K 4 L ,0 secon$s ,00)000 F 75)000

Stea$y State Current >atin" 45 a*%s C

E&a0ples of De*Co%pling De6ices * Rating


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EMS 2008 36

=inc Ri11on Installation for AC "itigation * Gro%nding


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EMS 2008 37

7inc 8round Mat

Connected

to Pipe

9est -tation

Coated Pipeline

E1uipotential Ground Mat - 2sed to Protect Personnel

from Electric Shoc) #at test stations3 0al0es3 etc4&


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EMS 2008 38

"itigation of AC Interference #sing Distri1%tedGal6anic Anodes

2%erhead 3AC 9ransmission 0ine

nderground Pipeline

!istributed -acriicial Anodes

Induced

,oltage

5ithout Anodes

5ith Anodes!istance


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EMS 2008 39

Testing t4e Effecti6eness of AC "itigation>

6 C %i%e#to#soi! %otentia! Aat test stations an$ a(oe"roun$ a%%urtenancesB to test for shoc haar$ o!ta"e

6 C=S A(oth


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T$E END

TRizk-DCandACInterference-NACE.ppt

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