Method

Advantages

Disadvantages

Im

p

r

e

s

s

e

d

C

u

r

r

e

n

t

M

e

t

h

o

d

(1) Output current and voltage are continuously adjustable

(1) Requires an external power source

(2) Large protection range

(2) Causes interference to nearby metal structures

(3) Not limited by soil resistivity

(3) High management and maintenance workload

(4) More economical for larger projects

(5) Long service life of protection devices

S

a

c

r

i

f

i

c

i

a

l

A

n

o

d

e

M

e

t

h

o

d

(1) No external power source required

(1) Uneconomical in high-resistivity environments

(2) No or minimal interference to nearby metal structures

(2) Not suitable for poor anti-corrosion coatings

(3) Low management workload

(3) Limited output current

(4) Economical for small projects

(5) Uniform protection current with automatic adjustment and high utilization

D

r

a

i

n

a

g

e

P

r

o

t

e

c

t

i

o

n

P

o

l

a

r

i

t

y

D

r

a

i

n

a

g

e

(1) Utilizes stray current to protect pipelines

(1) Causes interference to other structures

(2) Economical and practical

(2) Pipeline is unprotected when electric rail is out of operation

(3) Simple and easy method with low management requirements

(3) Difficult to control negative potential

(4) No concerns about stray current drainage

F

o

r

c

e

d

D

r

a

i

n

a

g

e

(1) Wide protection range

(1) Causes interference to other structures

(2) Voltage and current are continuously adjustable

(2) Requires an external power source

(3) Uses rails as anodes, simple structure

(3) Drainage points prone to overprotection

(4) Pipeline remains protected when electric rail is out of operation

(5) No anode interference