EN 14505:2005

SLOVENSKI STANDARD
01-julij-2005
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Cathodic protection of complex structures
Kathodischer Korrosionsschutz komplexer Anlagen
Protection cathodique des structures complexes
Ta slovenski standard je istoveten z: EN 14505:2005
ICS:
77.060 Korozija kovin Corrosion of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 14505
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2005
ICS 77.060
English version
Cathodic protection of complex structures
Protection cathodique des structures complexes Kathodischer Korrosionsschutz komplexer Anlagen
This European Standard was approved by CEN on 15 March 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14505:2005: E
worldwide for CEN national Members.

Contents
Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms and definitions.4
4 Criteria for the cathodic protection of complex structures .4
5 Prerequisites for the application of cathodic protection to a complex structure .5
6 Base data for design.6
7 Design and prerequisites .7
8 Installation of cathodic protection systems.10
9 Commissioning .11
10 Inspection and maintenance.12
Annex A (informative) Principle scheme of a complex structure .14

Annex B (informative) Example of an industrial complex structure.15
Annex C (informative) Reinforced concrete data in complex structures .16
Annex D (informative) Increasing soil potential .17
Annex E (informative) Groundbed data .21
Bibliography.24

Foreword
This European Standard (EN 14505:2005) has been prepared by Technical Committee CEN/TC 219
“Cathodic protection”, the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by October 2005, and conflicting national standards shall be withdrawn at
the latest by October 2005.
It may be difficult to obtain complete cathodic protection of certain structures when following the general
guidelines in EN 12954. This may be due to an electrical connection to one or more metal structures
(electrodes) situated in the same electrolyte as the structure, which is to be protected. In particular, the
structure may be earthed in order to mitigate electrical hazards or the connection to the other structures may
be dictated by construction or operational requirements.
An electrical connection to a foreign structure can result in a significantly increased cathodic protection current
demand, since the current flows not only to the structure to be protected but also to the foreign structure. This
unwanted increased current demand is enhanced when the foreign structure consists of a metal, which is
more noble (having a more positive resting potential) than the metal in the structure to be protected.
Connection to a copper earthing electrode or to the steel reinforcement in a concrete structure are examples
of the latter.
These difficulties can mean that a significantly increased cathodic protection current is required because of
structures electrically connected to the structure to be protected, resulting in inadequate cathodic protection,
current distribution and shielding effects.
For this reason, the term “complex structure” has been used. It does not refer to the complexity of the structure or
to the complexity of the cathodic protection system.
In such conditions the prerequisites, the criteria and the methods described in the present document expand
those given in EN 12954.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and United Kingdom.
1 Scope
This European Standard applies to the cathodic protection of complex structures. It is applicable to structures,
which are to be cathodically protected, but cannot be electrically isolated, whether for technical or safety
reasons, from foreign metallic structures situated in the same electrolyte as the structure to be protected.
Such a structure is referred to as a “complex structure”.
This European Standard is not applicable to structures that can be protected in accordance with EN 12954.
When contacts with foreign structures or defective isolation from foreign structures exist, but can be corrected,
EN 12954 is applicable instead of this document. As an example pipeline network distribution systems are not
considered to be complex structures
It is assumed in this document that the design, installation, commissioning, inspection and maintenance are
entrusted to adequately trained, experienced, competent and reliable personnel in order to achieve effective
and efficient cathodic protection.
Annexes A and B show the principle scheme of a complex structure with examples.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 12954:2001, Cathodic protection of buried or immersed metallic structures — General principles and
application for pipelines.
EN 50162, Protection against corrosion by stray current from direct current systems.
3 Terms and definitions
For the purposes of this European Standard, the terms and definitions given in EN 12954:2001 and the following
apply.
NOTE For other definitions related to corrosion, refer to EN ISO 8044:1999.
3.1
complex structure
structure composed of the structure to be protected and of one or more foreign electrodes, which, for safety or
technical reasons, cannot be electrically separated from it
3.2
foreign electrode
electrode (anode or cathode), in contact with the structure under consideration
NOTE a foreign anode is a foreign electrode, which has a more negative potential than the structure, a foreign
cathode is a foreign electrode, which has a more positive potential than the structure.

4 Criteria for the cathodic protection of complex structures
For complex structures, the cathodic protection criteria defined in EN 12954 should be used where possible.
Indeed, the characteristics of complex structures and the special influential factors (see Clause 5) which can occur
means that it is not always possible on every part of the complex structure to determine by measurement whether
these criteria of cathodic protection are met. In this case alternative methods of verification may be selected to
ensure an adequate reduction of the corrosion rate. Particular attention should be paid to the selection of these
alternative methods, and these will depend upon the structure and the soil characteristics.
The following three alternative methods may be used as criteria. They are based upon practical experience
and are widely used. All structure to electrolyte potential measurements are stated with respect to a
copper/saturated copper sulphate reference electrode.
a) Potential measurement method
An on potential E equal to or more negative than –1,2 V, if the measuring point is outside the area of
on
influence of the large foreign cathode (e.g. reinforced concrete or copper earthing system) and if the soil
resistivity is sufficiently low (less than about 100 Ω⋅m) with the exception that an on potential E more
on
negative than –0,8 V could be acceptable at entries to, and in the vicinity (within 0,5 m) of large foreign

cathodes (demonstrating that the effect of a galvanic cell with the large foreign cathode is mitigated).
b) Current method
The purpose of this method is to demonstrate that current is able to enter the structure at critical locations
either:
1) directly (i.e. when the protection current is switched on, a negative shift from the free corrosion
potential E by at least 0,3 V indicating that probably sufficient current is entering the structure); or
n
2) by means of either current density or potential shift measurements at test probes or coupons.
NOTE A critical location is location where the probability to have an anodic current leaving the structure to be protected
is high (e.g., vicinity of foreign cathode due to galvanic couple, heterogeneity of the soil or shielding effect).
c) Depolarisation measurement method
A positive shift (depolarisation) on test probes or coupons of at least 0,1 V measured from immediately after
disconnection (E ) to 1 h after disconnection from the structure indicates that the structure is polarized. These
off
test probes/coupons are disconnected only for measurements.
One of these alternative criteria shall be used as a minimum. More than one of these alternative criteria may
be required to verify adequate protection over the entire complex structure. Other criteria can be used if they
can be shown to reduce the external corrosion rate to an acceptable level.
5 Prerequisites for the application of cathodic protection to a complex structure
5.1 General
The cathodic protection system depends on the size and shape of the complex structure, the type of coating,
the aggressive action of the soil and its resistivity, d.c. and a.c interference, national regulations, and also on
the technical and economic criteria.
To achieve cathodic protection, the conditions given in 5.2 to 5.4 should be satisfied.
5.2 Electrical continuity
In the case of a complex structure, all metallic parts of the structure to be protected should be electrically
continuous. Foreign electrodes should also be electrically continuous.
5.3 Electrical isolation
For the cathodic protection system to be properly designed, the form and extent of the structure should be clearly
defined in terms of its location and electrical isolation from foreign structures.
If the electrical isolation is ineffective and cannot be restored to its original condition, then the extent of the
complex structure should be revised to take this into account.
5.4 External coating
Protective coatings are not always applied to components in a complex structure (e.g. earthing systems).
Uncoated components significantly increase protection current demands and thus add to the difficulties of the
application of cathodic protection and increase the risk of interference. Wherever possible, buried metallic
components should be suitably coated.
6 Base data for design
6.1 General
In addition to following the principles laid out in EN 12954, other specific data, as given in 6.2 to 6.8, should be
used when dealing with complex structures.
6.2 Structure details
The surface area of all buried or immersed components of a complex structure should be ascertained as well
as the status of the coating (if any).
6.3 Coatings
Types of the different coating applied on all components of a complex structure should be taken into account.
6.4 Environment
Depending on the composition of some parts of a complex structure, particular environmental conditions
should be considered, for example, the chloride content of the electrolyte when an integral part of a complex
structure is m
...