11 - NRG - Cathodic Protection Design

Pipeline Design Training

Cathodic Protection Design 1 !"g"st #$$

Pipeline Design Training &od"le I * +verview !"g"st # ,' !"g"st #- /' &r. Eng 0in NG 0 &  Pipe Allo$able Applicable Codes

On-bottom Stability (Concrete Coating) Design

Wall Thickness Design

4

5 Cathodic Protection Design

Epansion Calc!lations

"ree Span Calc!lations

"leibility Analysis #ethodology

On-bottom %o!ghness Analysis

6

1se o. Spoilers .or Pipe Sel.b!rial

/ 1ncon+entional

Workshop* re+ision* eercise

against Anchors* Wa+e ,i!e.action / Earth!ake

&8

7

Pipeline Constr!ction - Con+entional

Pipeline Protection

2nstallation Engineering (&3')

2nstallation Engineering ('3')

Pipeline Design Training &od"le I * 2ched"le Weekending A!g  A!g && A!g &6 A!g '0 1 #



3

%

-

4

1$ 11 13 1( 1 1% 1- #1 ## # #3 #( #-

 Applicable Codes, Wall Thickness Design On-bottom Stability (Concrete Coating) Design Pipe !pansion Calc"lations, #le!ibility Analysis $ethodology  Allo%able #ree Span Calc"lations, On-bottom &o"ghness Analysis Pipeline Protection against Anchors, Wa'e i"e*action + arth"ake Cathodic Protection Design se o* Spoilers *or Pipe Sel*-b"rial Pipeline Constr"ction - Con'entional + ncon'entional nstallation ngineering

Workshop* re+ision* eercise

'6

Today

Cathodic Protection Design 



In the cathodic protection anal'sis calc"lations are carried o"t to ens"re that the anodes provided are s"5cient to provide the total c"rrent needed to protect the pipeline d"ring its design li6e.  The initial and 7nal c"rrent demands are to /e chec8ed to ens"re that the anodes can provide s"5cient c"rrent o"tp"t to polarise the pipeline thro"gho"t its entire li6e.

Cathodic Protection Design 9cont:d; 



2? t

= =

u

=

e

=

Total nett anode mass re"ired (kg) $ean (maintenance) design c"rrent density (A6m 0) @o"rs per year (hr6year) Design li*e (years)  Anode "tilisation *actor lectrochemical e**iciency (A.h6kg)

The total nett anode mass pro'ided, $ pro'ided , m"st be more than or e"al to that re"ired, $re"ired  *or cathodic protection to be s"stained thro"gho"t the design li*e.

!node C"rrent +"tp"t 

 The anode c"rrent o"tp"t Ia is o/tained 6rom +hm:s Faw= a Where a

= o o"tp"t =  E c (A)

=

 E co −  E ao  Raf  

initial6*inal c"rrent Design protecti'e potential (9)

 E a

=

Design closed circ"it potential o* the anode (9)

R af 

=

Anode resistance ( Ω)

o

= ρ =

A

=

0.315 ρ   A

*or *l"sh-mo"nted bracelet anode

Sea %ater resisti'ity ( Ω.m) AnodeBs e!posed s"r*ace area (m 0)

!node C"rrent +"tp"t 9cont:d; 







 The 7nal anode resistance is determined 6rom the 7nal anode dimensions.  The 7nal anode resistance is calc"lated /' ass"ming that the anode is cons"med to its "tilisation 6actor " which wo"ld give a 7nal eposed s"r6ace area and corresponding anode resistance. ?or cathodic protection to /e eHective thro"gho"t the design li6e the 7nal c"rrent o"tp"t Ia m"st e"al or eceed the 7nal c"rrent demand Ic. Ia 97nal;  Ic 97nal;.

Eamples ?or Comparison +6 RP*03$1 and RP*?$1 P2PE,2:E A:D A:ODE DATA Parameters

1nit

?al!e

C

3?

C

3?

DS #, T

Eear

/?

PP OTSD DA$T&

mm

:81.1 (32-inch)

-

3-layer P

mm

0./?

PP T@

m

/???

 AOD $AT&A

-

Al-based

mm

4?

g6cm3

0.>??

kg

8/?

nternal *l"id Temperat"re  AOD S&#AC T$P&AT&

FT&A COAT $AT&A FT&A COAT T@CGSS

 AOD T@CGSS  AOD DSTE  AOD $ASS

o

o

CATHODIC PROTECTION DATA AND RESULTS Parameters

1nit

%P-