ISO 22426-2020 pdf download

ISO 22426-2020 pdf download.Assessment of the effectiveness of cathodic protection based on coupon measurements. 5 Application prlndples 5.1 IR-free potential measurements The traditional coupon measurement technique has bern used to dcincnstratc conformity of the coupon polarization, which is taken to be representative of the structure coating defects in accordance with the requirements of ISO IS%H9L There are several situations where the use of coupons is a frasihI alternative to lRfree potential measurements directly on the structure. In particular, when accurate measurements directly on the structure itself are probhonatw. Examples include: — in areas affected by traction stray currents and telluric currents, — when dealing with the CP of complex structures; — interference caused by two or more cathodically protected str1icture crocs: rig or sharing the same right-oV-way — interference betwren both parts of an Isolating omnt for a structure protected by two different CP systenis oneon each side olthe mint: — effects from equalizing curreuits from .sdiaccnt coating defects: the coupon may be regarded ax one single coating defect exposed in the chemistry of the soil exactly where the coupon has been buried, whereas measurenwnts on the structure may include a range of coating defects exposed in varying individual soil chemistries leading to the formation of potential dilferences and varying current dematid; — In areas where the CP is applied using several CP sources, and Ii Is not possible or economically practical to synchronously turn off these CP sources. EN 13509, EN 50162. ISO )8086 and ISO 15589-1 allow for the use of coupons in such Instances. 5.2 DC and AC currents and current densities Th. use of coupons allows loran assessment of current densities in order to demonstrate conformityto ISO 10086 and EN 50162. The DC current consumed by a coupon is primarily used for accessing the cignithance of DC stray current interference, EN S0162 describes a procedure for the demonstration of effectiveness of CP based on current density, This Involves measuring the DC current throughout a period of typIcally 24 h. From these measurements, a penod is defined in which no interference is present (e.g. hours during the night when trains do not operate). This period is used as the reference value md the measure of the reference current under normal CP Based on the analysis of these currents, an assessment of the effectiveness of CP under DC interterence Is performed Apart from the risk of corrosion due...