ISO 24656:2022 洋上風力発電所の電気防食 | ページ 6

3.1

atmospheric zone

zone located above the splash zone

3.2

buried zone

zone located under the seabed or expected scour level, whichever is lower

3.3

CP design life

time for which the CP is designed to protect the structure

Note 1 to entry: This may be different to the structure design life or structure service life.

3.4

doubler plate

plate welded onto a member to locally reinforce it or to isolate it from further welding work

3.5

electrolyte

medium in which electric current is transported by ions. In the context of this document, seawater or seabed

3.6

frequently wetted zone

FWZ

water level, WL(t), plus significant wave height, H_mo

Note 1 to entry: See Annex B for details.

3.7

free board level

FBL

water level for floating structures

Note 1 to entry: For calculation of frequently wetted zone, it will replace WL(t)

3.8

HAT

highest astronomical tide

level of the highest astronomical tide

3.9

hybrid cathodic protection system

system comprising both impressed current and galvanic anodes

3.10

inspection

examination of equipment to determine its continued performance characteristics, whether undertaken on a regular program basis or carried out as a simple operation

3.11

IR error

error in measured steel to electrolyte potential caused by the protection current or any other current flowing through the resistive environment

3.12

jacket structure

multi-legged lattice braced structure

3.13

J-tube

curved tubular conduit designed and installed on a structure to support and guide cables

3.14

LAT

lowest astronomical tide

level of the lowest astronomical tide

3.15

marine sediments

top layer of the seabed composed of water saturated solid materials of various densities

3.16

metocean data

meteorological and oceanographic data, often given as hourly statistics

3.17

monitoring

activity continuously on-going or sporadically undertaken at fixed locations to determine the performance of a CP system or parameters related to the performance

Note 1 to entry: Typically, monitoring utilizes fixed sensors, the data from which can be data logged.

3.18

monopile

foundation element driven or drilled into the seabed to support a transition piece and/or tower

3.19

over-polarization

occurrence in which the structure to electrolyte potentials are more negative than those required for satisfactory cathodic protection

Note 1 to entry: Over-polarization provides no useful function and might even cause damage to the structure

3.20

owner

structure owner, or developer or operator, all or any of which may have responsibility for matters related to corrosion protection

3.21

primary steel

primary load carrying elements (monopile, jacket, hull and other steel structures)

3.22

re-polarization

situation where the steel is polarized after a depolarization event

3.23

retrofit cathodic protection

provision of CP equipment, either as a complete or a partial system, to an existing structure either to remedy CP performance deficiencies or to extend the CP system life

3.24

salinity

quantity of inorganic salts dissolved in the seawater

Note 1 to entry: The standardised measurement is based on the determination of the electrical conductivity of the seawater.

Note 2 to entry: Salinity is expressed in grams per kilogramme (g/kg) or as parts per thousand (ppt or ‰).

3.25

scour

removal of seabed soils by sea currents and waves or caused by structural elements interrupting the natural flow regime above the sea floor

3.26

seabed

interface between seawater and solids of the buried zone (3.2) including the marine sediments (3.15)

3.27

secondary steel

steel which is not primary steel, hence used for access (boat landing, ladders, decks and support for equipment)

3.28

shallow water

water of such depth that surface waves are noticeably affected by bottom topography

Note 1 to entry: Typically, this implies a water depth equivalent to half the wavelength^[33]. For all practical purposes in this document, it is understood as depth less than −30 m LAT

3.29

significant wave height

H_mo

mean level of the third largest waves in open sea

3.30

splash zone

external region of support structure that is frequently wetted due to the wave and tidal variations. A more detailed definition of splash zone is given in IEC 61400-3-1^[15]. In this document the frequently wetted zone is included as the upper boundary to which current demand for CP shall be included

3.31

structure service life

anticipated life of the windfarm structure.

Note 1 to entry: This includes a period for storage, transport, installation, operating the wind farm and a possible period for decommissioning

3.32

suction bucket

foundation element that is sucked into the seabed

3.33

surveying

process of carrying out inspection using a defined procedure

Note 1 to entry: In this document surveying is also used to describe the process of taking cathodic protection measurements, not using fixed and data logged sensors, but using a defined procedure

3.34

tidal zone

zone located between LAT and HAT

3.35

transition piece

intermediate structure between the monopile and the tower

3.36

wave crest and trough

height of seawater above and depth of below still water level due to waves

Note 1 to entry: See Figure 1 below.

Figure 1 — Water depth, tides and storm surges, from ISO 19901-1 ^[10]

a) Tides	b) Tide+storm surge=still water level	c) Wave profile superimposed on water level

Key

Key to distance elevation			Key line types
1	lowest astronomical tide (LAT)	6	tide associated with storm (shown positive but may be positive or negative)		seafloor
2	mean sea level (MSL)	7	storm surge (shown positive but may be positive or negative)		tide levels
3	highest astronomical tide (HAT)	8	still water (or"storm water") level		surge or surge+tide levels
4	tidal range	9	crest elevation		wave profile
5	tidal datum (commonly LAT or MSL but may be other)	0	trough elevation