ISO 15589-2:2012 石油、石油化学、天然ガス産業—パイプライン輸送システムの陰極防食—パート2：オフショアパイプライン | ページ 6

3.1

anode potential

anode-to-electrolyte potential

3.2

anode sled

anodes installed on a structure and connected to the pipeline by a cable

3.3

closed-circuit anode potential

anode potential while electrically linked to the pipeline to be protected

3.4

coating breakdown factor

f_c

ratio of current density required to polarize a coated steel surface as compared to a bare steel surface

3.5

cold shut

horizontal surface discontinuity caused by solidification of the meniscus of the partially cast anodes as a result of interrupted flow of the casting stream

3.6

driving voltage

difference between the pipeline/electrolyte potential and the anode/electrolyte potential when the cathodic protection is operating

3.7

electric field gradient

change in electrical potential per unit distance through a conductive medium, arising from the flow of electric current

3.8

electrochemical capacity

ε

total amount of electric charge that is produced when a fixed mass (usually 1 kg) of anode material is consumed electrochemically

Note 1 to entry: Electrochemical capacity is expressed in ampere hours.

3.9

final current density

estimated current density at the end of the lifetime of the pipeline

Note 1 to entry: Final current density is expressed in amperes per square metre.

3.10

hydrogen-induced stress cracking

HISC

cracking due to a combination of load and hydrogen embrittlement caused by the ingress of hydrogen formed at the steel surface due to the cathodic polarization

3.11

IR drop

voltage due to any current, measured between two points of the metal of the pipe or two points of the electrolyte, such as seawater or seabed, in accordance with Ohm’s law

Note 1 to entry: IR drop and electric field gradient are related terms.

3.12

master reference electrode

reference electrode, calibrated with the primary calibration reference electrode, used for verification of reference electrodes that are used for field or laboratory measurements

3.13

mean current density

estimated average cathodic current density for the entire lifetime of the pipeline

Note 1 to entry: Mean current density is expressed in amperes per square metre.

3.14

protection potential

structure-to-electrolyte potential for which the metal corrosion rate is considered as insignificant

3.15

pitting resistance equivalent number

PREN

number, developed to reflect and predict the pitting resistance of a stainless steel, based on the proportions of Cr, Mo, W and N in the chemical composition of the alloy

3.16

primary calibration reference electrode

reference electrode used for calibration of master reference electrodes

3.17

remotely operated vehicle

ROV

underwater vehicle operated remotely from a surface vessel or installation

[SOURCE: ISO 14723]

3.18

riser

part of an offshore pipeline, including any subsea spool pieces, which extends from the seabed to the pipeline termination point on an offshore installation

[SOURCE: ISO 13623]

3.19

utilization factor

µ

fraction of the anodic material weight of a galvanic anode that can be consumed before the anode ceases to provide the minimum required current output