oSIST prEN 12451:2026

• Abstract:

  This document specifies the composition, property requirements and tolerances on dimensions and form for seamless round drawn copper and copper alloy tubes for heat exchangers, condensers, evaporators and desalination equipment. It is applicable to copper and copper alloy tubes supplied in the size range from 6 mm up to and including 76 mm outside diameter and from 0,5 mm up to and including 3 mm wall thickness.; The sampling procedures and the methods of test for verification of conformity to the requirements of this document are also specified.

• Status: Not Published
• Public Enquiry End Date: 09-Nov-2026
• ICS: 23.040.15 - Non-ferrous metal pipes
• ICS: 77.150.30 - Copper products
• Technical Committee: INEK - Nonferrous metals
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 07-Sep-2026
• Due Date: 25-Jan-2027
• Directive: Harmonized Standard2014/68/EU - Directive 2014/68/EU of the European Parliament and of the Council of 15 May 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of pressure equipment
• Mandate: M/071 - Mandate to CEN for standardization in the field of Pressure equipment
• Mandate: M/601 - COMMISSION IMPLEMENTING DECISION of 1.3.2024 on a standardisation request to the European Committee for Standardization and the European Committee for Electrotechnical Standardization as regards pressure equipment and assemblies in support of Directive 2014/68/EU of the European Parliament and of the Council
• Ref Project: prEN 12451 - Copper and copper alloys - Seamless, round tubes for heat exchangers

• Revises: SIST EN 12451:2012 - Copper and copper alloys - Seamless, round tubes for heat exchangers
• Effective Date: 11-Jun-2025

Overview

oSIST prEN 12451:2026:2026, published by CEN, establishes comprehensive requirements for seamless, round tubes made of copper and copper alloys used in heat exchangers, condensers, evaporators, and desalination equipment. This standard covers product composition, mechanical properties, dimensions, tolerances, and test methods, ensuring high performance and reliability in both industrial and marine settings. The standard applies to tubes with outside diameters from 6 mm up to 76 mm and wall thicknesses from 0.5 mm to 3 mm.

Key Topics

• Material Composition
  Specifies permitted copper and copper alloys, with clear requirements for alloy composition to address conductivity, strength, and corrosion resistance.

• Mechanical Properties & Conditions
  Defines tensile strength, hardness, elongation, and material conditions (e.g. annealed, stress-relieved) to meet demanding operational environments.

• Dimensional Tolerances
  Outlines strict limits for outside diameter, wall thickness, length, and circularity to ensure tubes properly fit into heat exchanger assemblies.

• Surface Quality
  Sets out conditions for surface cleanliness and finish, including requirements for deburred ends and the presence of any superficial films or oxides.

• Testing and Verification
  Details mandatory mechanical and technological tests such as tensile, hardness, drift expanding, grain size, and stress corrosion resistance. Includes procedures for sampling, retesting, eddy current, hydrostatic, and pneumatic pressure tests.

• Inspection and Documentation
  Stipulates requirements for conformity declarations and inspection documentation, referencing EN ISO/IEC 17050 and EN 10204 standards.

Applications

Seamless copper and copper alloy tubes that comply with oSIST prEN 12451:2026 are critical in industries where thermal conductivity, corrosion resistance, and dimensional precision are essential:

• Heat Exchangers
  Used in HVAC systems, power generation plants, and industrial cooling, where efficient heat transfer and durability are required.

• Condensers and Evaporators
  Essential in refrigeration and air conditioning equipment, ensuring reliability and long service life.

• Desalination Equipment
  Copper nickel alloys covered by the standard are especially suited for seawater applications, offering resistance to corrosion and biofouling.

• Engineering and Process Industries
  Utilized wherever liquid or gas heat transfer is fundamental, such as in chemical plants or marine vessels.

Related Standards

• EN 1057 - Seamless, round copper tubes for water and gas in sanitary and heating systems.
• EN 12449 - Seamless, round tubes for general purposes.
• EN 12450 - Seamless, round copper capillary tubes.
• EN 12452 - Rolled, finned, seamless tubes for heat exchangers.
• EN 12735 (Parts 1 & 2) - Seamless, round copper tubes for air conditioning and refrigeration.
• EN 13348 - Seamless, round copper tubes for medical gases or vacuum.
• EN 764-5 - Pressure equipment, inspection documentation for metallic materials.
• EN 1971-1/2 - Eddy current testing on seamless round copper tubes.

For those manufacturing, specifying, or purchasing tubes for heat exchangers and related equipment, adherence to oSIST prEN 12451:2026 assures product compatibility, safety, and optimal performance in line with European and international standards. Incorporating these tubes improves heat transfer efficiency and operational reliability across critical infrastructure sectors.

SLOVENSKI STANDARD
01-november-2026
Baker in bakrove zlitine - Nevarjene cevi z okroglim prerezom za toplotne
izmenjevalnike
Copper and copper alloys - Seamless, round tubes for heat exchangers
Kupfer und Kupferlegierungen - Nahtlose Rundrohre für Wärmeaustauscher
Cuivre et alliages de cuivre - Tubes ronds sans soudure pour échangeurs thermiques
Ta slovenski standard je istoveten z: prEN 12451
ICS:
23.040.15 Cevi iz neželeznih kovin Non-ferrous metal pipes
77.150.30 Bakreni izdelki Copper products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2026
ICS 23.040.15; 77.150.30 Will supersede EN 12451:2012
English Version
Copper and copper alloys - Seamless, round tubes for heat
exchangers
Cuivre et alliages de cuivre - Tubes ronds sans soudure Kupfer und Kupferlegierungen - Nahtlose Rundrohre
pour échangeurs thermiques für Wärmeaustauscher
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 133.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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 CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12451:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Designations . 6
4.1 Material . 6
4.1.1 General . 6
4.1.2 Symbol. 6
4.1.3 Number . 6
4.2 Material condition . 6
4.3 Product . 7
5 Ordering information . 8
6 Requirements . 9
6.1 Composition . 9
6.2 Mechanical properties . 9
6.3 Dimensions and tolerances . 9
6.3.1 General . 9
6.3.2 Outside diameter . 9
6.3.3 Wall thickness . 10
6.3.4 Length . 10
6.3.5 Tolerances on form . 10
6.4 Surface quality . 10
6.5 Technological requirements . 10
6.5.1 Drift expanding . 10
6.5.2 Residual stress level . 10
6.5.3 Grain size . 11
6.5.4 Freedom from defects . 11
7 Sampling . 11
7.1 General . 11
7.2 Analysis. 11
7.3 Mechanical tests and stress corrosion resistance test . 11
8 Test methods . 11
8.1 Analysis. 11
8.2 Tensile test . 11
8.3 Hardness test . 12
8.4 Technological tests . 12
8.4.1 Drift expanding test . 12
8.4.2 Stress corrosion resistance test . 12
8.4.3 Average grain size determination . 12
8.5 Freedom from defects tests . 12
8.5.1 General . 12
8.5.2 Eddy current test . 12
8.5.3 Hydrostatic test . 13
8.5.4 Pneumatic test . 13
8.6 Retests . 13
8.6.1 Analysis, tensile, hardness, drift expanding and grain size tests . 13
8.6.2 Stress corrosion resistance test . 13
8.7 Rounding of results . 14
9 Confirmation of conformity and inspection documentation . 14
9.1 Confirmation of conformity . 14
9.2 Inspection documentation . 14
10 Marking, packaging, labelling . 14
Annex A (normative) U-bend seamless copper and copper alloy heat exchanger tubes . 19
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2014/68/EU (Pressure Equipment Directive) aimed to be
covered . 21
Bibliography . 22

European foreword
This document (prEN 12451:2026) has been prepared by Technical Committee CEN/TC 133 “Copper and
copper alloys”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 12451:2012.
This document includes the following significant technical changes with respect to EN 12451:2012:
— normative references updated;
— Directive 97/23/EC replaced by 2014/68/EU;
— EN 1655 replaced by EN ISO/IEC 17050-1:2010 and EN ISO/IEC 17050-2:2004;
— in 7.1 the sampling rate modified and the billet inward stage included for carrying out analysis;
— Table 6 “Sampling rate” deleted.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
For the relationship with EU Legislation, see informative Annex ZA, which is an integral part of this
document.
This is one of a series of European Standards for copper and copper alloy tubes. Other products are
specified as follows:
— EN 1057, Copper and copper alloys — Seamless, round copper tubes for water and gas in sanitary and
heating applications
— EN 12449, Copper and copper alloys — Seamless, round tubes for general purposes
— EN 12450, Copper and copper alloys — Seamless, round copper capillary tubes
— EN 12452, Copper and copper alloys — Rolled, finned, seamless tubes for heat exchangers
— EN 12735-1, Copper and copper alloys — Seamless, round copper tubes for air conditioning and
refrigeration — Part 1: Tubes for piping systems
— EN 12735-2, Copper and copper alloys — Seamless, round copper tubes for air conditioning and
refrigeration — Part 2: Tubes for equipment
— EN 13348, Copper and copper alloys — Seamless, round copper tubes for medical gases or vacuum
— EN 13349, Copper and copper alloys — Pre-insulated copper tubes with solid covering
— EN 13600, Copper and copper alloys — Seamless copper tubes for electrical purposes
1 Scope
This document specifies the composition, property requirements and tolerances on dimensions and form
for seamless round drawn copper and copper alloy tubes for heat exchangers, condensers, evaporators
and desalination equipment. It is applicable to copper and copper alloy tubes supplied in the size range
from 6 mm up to and including 76 mm outside diameter and from 0,5 mm up to and including 3 mm wall
thickness.
The sampling procedures and the methods of test for verification of conformity to the requirements of
this document are also specified.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 764-5:2014, Pressure equipment — Part 5: Inspection documentation of metallic materials and
compliance with the material specification
EN 1971-1:2019, Copper and copper alloys — Eddy current test for measuring defects on seamless round
copper and copper alloy tubes — Part 1: Test with an encircling test coil on the outer surface
EN 1971-2:2019, Copper and copper alloys — Eddy current test for measuring defects on seamless round
copper and copper alloy tubes — Part 2: Test with an internal probe on the inner surface
EN 10204:2004, Metallic products — Types of inspection documents
EN 16090:2019, Copper and copper alloys — Estimation of average grain size by ultrasound
EN ISO 196:1995, Wrought copper and copper alloys — Detection of residual stress — Mercury (I) nitrate
test (ISO 196:1978)
EN ISO 2624:1995, Copper and copper alloys — Estimation of average grain size (ISO 2624:1990)
EN ISO 6507-1:2023, Metallic materials — Vickers hardness test — Part 1: Test method (ISO 6507-1:2023)
EN ISO 6892-1:2019, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
(ISO 6892-1:2019)
EN ISO 8493:2004, Metallic materials — Tube — Drift-expanding test (ISO 8493:1998)
EN ISO/IEC 17050-1:2010, Conformity assessment — Supplier’s declaration of conformity — Part 1:
General requirements (ISO/IEC 17050-1:2004, corrected version 2007-06-15)
EN ISO/IEC 17050-2:2004, Conformity assessment — Supplier’s declaration of conformity — Part 2:
Supporting documentation (ISO/IEC 17050-2:2004)
ISO 6957:1988, Copper alloys — Ammonia test for stress corrosion resistance
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
seamless round tube
hollow semi-finished product, circular in cross-section, having a uniform wall thickness, which at all
stages of production has a continuous periphery
3.2
mean wall thickness
arithmetical mean of the maximum and minimum wall thicknesses at the same cross-section of the tube
3.3
deviation from circular form
difference between the maximum and minimum outside diameters measured at any one cross-section of
the tube
[SOURCE: EN 1057:2006+A1:2010, 3.6]
4 Designations
4.1 Material
4.1.1 General
The material is designated either by symbol or by number (see Table 1).
4.1.2 Symbol
The material symbol designation is based on the designation system given in ISO 1190-1:1982.
NOTE Although material symbol designations used in this document might be the same as those in other
standards using the designation system given in ISO 1190-1:1982, the detailed composition requirements are not
necessarily the same.
4.1.3 Number
The material number designation is in accordance with the system given in EN 1412:2016.
4.2 Material condition
For the purposes of this document, the following designations, which are in accordance with the system
given in EN 1173:2008, apply for the material condition:
R. Material condition designated by the minimum value of tensile strength requirement for
the product with mandatory tensile property requirements.
H. Material condition designated by the minimum value of hardness requirement for the
product with mandatory hardness requirements.
S (suffix) Material condition for a product which is stress relieved.
NOTE 1 Products in the H. condition can be specified to Vickers or Brinell hardness. The condition designation
H. is the same for both hardness test methods.
NOTE 2 Products in the R. or H. condition can be specially processed (i.e. mechanically or thermally stress
relieved) in order to lower the residual stress level to improve the resistance to stress corrosion (see 6.5.2).
Exact conversion between material conditions designated R. and H. is not possible.
Except when the suffix S is used, the material condition is designated by only one of the above
designations.
4.3 Product
The product designation provides a standardized pattern of designation from which a rapid and
unequivocal description of a product can be conveyed in communication. It provides mutual
comprehension at the international level with regard to products which meet the requirements of the
relevant document.
The product designation is no substitute for the full content of the standard.
The product designation for products to this document shall consist of:
— denomination (tube);
— number of this document (EN 12451);
— material designation, either symbol or number (see Table 1);
— material condition designation (see Table 2);
— nominal cross-sectional dimensions (outside diameter × wall thickness).
The derivation of a product designation is shown in the following example.
EXAMPLE Tube conforming to this document, in material designated either CuNi10Fe1Mn or CW352H, in
material condition H075, with nominal outside diameter 22 mm and nominal wall thickness 2,0 mm, will be
designated as follows:
5 Ordering information
To facilitate the enquiry, order and confirmation of order procedures, the following information shall be
specified:
NOTE 1 Heat exchanger tube can also be supplied as U-bend tube. For specific product and ordering information,
see Annex A.
a) quantity of product required (number of pieces, length or mass);
b) denomination (tube);
c) number of this document (EN 12451);
d) material designation (see Table 1);
e) material condition designation (see 4.2 and Table 2);
f) nominal cross-sectional dimensions (outside diameter × wall thickness);
g) nominal length (see 6.3.4).
NOTE 2 It is advised that the product designation, as described in 4.3, is used for items b) to f).
In addition, the enquiry and order shall contain the following, if required:
h) whether minimum wall thickness is required (see 6.3.3.2);
i) whether the tubes in alloy CuNi10Fe1Mn (CW352H) are for sea water application (see Table 1), and
if so, the composition limits required;
j) whether the tubes are required to pass a stress corrosion resistance test (see 6.5.2);
k) whether the tubes in hard condition are required with annealed ends;
l) whether the tubes are required to pass freedom from defects tests (see 6.5.4), and if so, which test
method is to be used (see 8.5);
m) whether the tubes are for subsequent welding applications (see Table 1);
n) whether special surface quality is required (see 6.4);
o) whether a confirmation of conformity is required (see 9.1);
p) whether an inspection document is required, and if so, which
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