ISO 15589-1:2015 石油、石油化学、天然ガス産業—パイプラインシステムの陰極防食—パート1：陸上パイプライン | ページ 6

3.1

anode backfill

added material immediately surrounding a buried anode

3.2

bond

metal conductor, usually copper, connecting two points on the same or on different structures

3.3

cathodic protection system

all active and passive components associated with the provision of active external corrosion protection and its monitoring

Note 1 to entry: Cathodic protection is obtained either by impressed current or by galvanic anodes using one or more stations.

Note 2 to entry: Impressed current and galvanic anode systems consist of all the equipment necessary for the application of cathodic protection, such as impressed current stations, galvanic anodes, bonds, and isolating joints.

3.4

coupon

metal sample of defined dimensions made of a metal equivalent to the metal of the pipeline

3.5

coating breakdown factor

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

3.6

d.c. decoupling device

equipment that provides a low-impedance path for a.c. and high resistance for d.c.

3.7

drain point

location of the cable connection to the protected pipeline through which the protective current returns to its source

3.8

drainage

transfer of stray current between structures by means of a deliberate bond

Note 1 to entry: See EN 50162 for drainage devices (direct drainage bond, resistance drainage bond, unidirectional drainage bond, and forced drainage bond).

3.9

drainage station

equipment and materials required to provide drainage of stray currents from affected systems

3.10

galvanic anode

electrode that provides current for cathodic protection by means of galvanic coupling

3.11

galvanic anode station

equipment and materials required to provide cathodic protection by the use of galvanic anodes

Note 1 to entry: Such materials and equipment include galvanic anodes and cables.

3.12

geological cell

corrosion cell constituted between two different parts of a single metallic pipeline in contact with different soils

3.13

groundbed

system of buried or immersed galvanic or impressed current anodes

3.14

impressed current anode

electrode that provides current for cathodic protection by means of impressed current

3.15

impressed current station

equipment and materials required to provide cathodic protection by impressed current

Note 1 to entry: Such materials and equipment include impressed current anodes, cables, and a d.c. source.

3.16

instant-OFF potential

OFF potential measured with a short delay after interruption with the aim of approaching as much as possible the IR-free potential

Note 1 to entry: A typical delay for direct measurements on pipeline is about 300 ms to prevent the influence of voltage spikes. On coupons, shorter delays are used.

3.17

IR drop

voltage that is the product of all currents flowing through the cathodic protection circuit and the resistance of the current path (mainly the electrolyte and the pipeline)

Note 1 to entry: This is derived from Ohm’s law (U = I × R).

3.18

IR-free potential

polarized potential

pipe to electrolyte potential without the voltage error caused by the IR drop due to the protection current or any other current

3.19

isolating joint

electrically insulating component inserted between two lengths of pipe to prevent electrical continuity between them

3.20

isolating spark gap

ISG

component with discharge distance for isolating electrically conductive installation sections

Note 1 to entry: In the event of lighting strike, the installation sections are temporarily connected conductively as the result of response of the discharge.

3.21

local earthing

earthed metallic electrode not directly electrically connected to any other main earthing system

3.22

measuring point

location where the actual potential measurement takes place

Note 1 to entry: In the case of pipe-to-electrolyte potential measurement, this refers to the location of the reference electrode.

3.23

ON potential

pipe-to-electrolyte potential measured while the cathodic protection system is continuously operating

3.24

OFF potential

pipe-to-electrolyte potential measured after interruption of all sources of applied cathodic protection current with the aim of approaching an IR-free potential

Note 1 to entry: The delay before measurements varies according to the circumstances.

3.25

pipe-to-electrolyte potential

difference in potential between a pipeline (or coupon) and a specified reference electrode in contact with the electrolyte at a point sufficiently close to, but without actually touching, the pipeline

3.26

pitting resistance equivalent number

PREN

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

3.27

polarization

change of pipe-to-electrolyte potential caused by the application of an external electrical current

3.28

probe

device incorporating a coupon that provides measurements of parameters used to assess the effectiveness of cathodic protection and/or corrosion risk

3.29

protection potential

pipe-to-electrolyte potential at which the metal corrosion rate is acceptable for the pipeline

3.30

reference electrode

electrode, having a stable and reproducible potential that is used as a reference in the measurement of electrode potentials

[SOURCE:ISO 8044]

3.31

remote earth

part of the electrolyte in which no measurable voltages, caused by current flow, occur between any two points

Note 1 to entry: This condition generally prevails outside the zone of influence of an earth electrode, an earthing system, an anode groundbed, or a protected pipeline.

3.32

rock jacket coating

coating that provides mechanical protection to the pipeline and is applied as bendable flexible coating

3.33

stray current

current flowing through paths other than the intended circuits

[SOURCE:Adapted from ISO 8044]

3.34

surge protective device

SPD

device intended to limit transient overvoltages and direct surge currents

Note 1 to entry: It contains at least one nonlinear component.

[SOURCE:IEC 62305‑1]

3.35

telluric current

current in the earth as a result of geomagnetic fluctuations

3.36

test station

monitoring station

installation that provides measuring and test facilities

Note 1 to entry: Such installations include cabling and pipeline connections.

3.37

utilization factor

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