ISO/FDIS 23300-1

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23300-1
ISO/TC 269/SC 1
Railway applications — Rail
Secretariat: AFNOR
welding —
Voting begins on:
2021-05-13
Part 1:
Voting terminates on:
General requirements and test
2021-07-08
methods for rail welding
Applications ferroviaires — Soudage des rails —
Partie 1: Exigences de portée générale et méthodes d'essais pour le
soudage des rails
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 SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 23300-1:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
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ISO/FDIS 23300-1:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Rail welding processes ................................................................................................................................................................................... 3

5 General process of rail welding ............................................................................................................................................................. 3

6 Approval/homologation of welding processes ..................................................................................................................... 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Non-destructive testing (NDT) .................................................................................................................................................. 4

6.3 Slow-bending test ................................................................................................................................................................................. 4

6.4 Past-the-post fatigue test ............................................................................................................................................................... 5

6.5 Macro examination .............................................................................................................................................................................. 5

6.6 Micro examination ............................................................................................................................................................................... 5

6.7 Hardness test ............................................................................................................................................................................................ 5

6.8 Drop-hammer test (optional) ..................................................................................................................................................... 5

6.9 Recording of defects ........................................................................................................................................................................... 5

6.10 Test result reports ................................................................................................................................................................................ 5

7 Acceptance in factory/track ..................................................................................................................................................................... 6

7.1 General ........................................................................................................................................................................................................... 6

7.2 Weld inspection ...................................................................................................................................................................................... 6

7.3 Straightness inspection ................................................................................................................................................................... 6

7.4 Documentation ....................................................................................................................................................................................... 8

8 Requirement on contractor/welder/inspector .................................................................................................................... 8

8.1 Contractor ................................................................................................................................................................................................... 8

8.2 Welder, operator and inspector ................................................................................................................................................ 8

8.3 Audit ................................................................................................................................................................................................................. 9

Annex A (normative) Slow-bending test method for rail foot in tension.....................................................................10

Annex B (normative) Slow-bending test method for rail head in tension ..................................................................13

Annex C (normative) Three-point bending fatigue test .................................................................................................................16

Annex D (normative) Four-point bending fatigue test ....................................................................................................................18

Annex E (normative) Macro examination.....................................................................................................................................................20

Annex F (normative) Micro examination ......................................................................................................................................................21

Annex G (normative) Hardness test ...................................................................................................................................................................24

Annex H (normative) Drop-hammer test ......................................................................................................................................................26

Annex I (normative) Recording of defects on fracture faces ....................................................................................................28

Annex J (normative) Ultrasonic testing ..........................................................................................................................................................30

Annex K (normative) Magnetic particle testing .....................................................................................................................................36

Annex L (normative) Dye penetrant testing ..............................................................................................................................................38

Annex M (informative) Examples of acceptance criteria for straightness..................................................................40

Bibliography .............................................................................................................................................................................................................................43

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

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This document was prepared by Technical Committee ISO/TC 269, Railway applications, Subcommittee

Any feedback or questions on this document should be directed to the user’s national standards body. A

Rail welding is an essential technology in the railway track domain for reducing noise and vibration on

Since environments (e.g. geography, deployable resources and energy affairs) differ by region and

railway line, rail welding processes have been developed to meet the requirements and conditions of

each environment. As a result, various rail welding processes exist, e.g. flash butt welding (FBW), gas

pressure welding (GPW), aluminothermic welding (ATW) and enclosed arc welding (EAW).

For this reason, a general rail welding standard on an international level covering conventional rail

welding processes was deemed necessary. This document contributes to the development of railways by

ensuring the quality of welded joints in terms of enhancing the reliability of train operation, improving

This document covers the general requirements for rail welding and is used in conjunction with the

subsequent parts of the ISO 23300 series, which cover the specific requirements for each welding

This document specifies requirements concerning the approval and/or homologation of welding

processes, contractors, welders, inspectors and acceptance of welded joints in the factory and/or track.

In this document, 43 kg/m to 75 kg/m new flat-bottomed rails of the same profiles and same steel

This document does not specify requirements or test methods specific to each welding process. These

This document does not cover the welding for construction of crossings, railway switches, signal bond

In this document, the qualifications of individuals and organizations that are approved by the railway

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.

ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:

Tension/compression testing machines — Calibration and verification of the force-measuring system

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

either the railway regulator or the owner of a railway infrastructure or the custodian with a delegated

company which provides a rail welding process which is approved by the railway authority (3.1) to

organization or centre responsible for training welders (3.5) and which is approved by the railway

authority (3.1), and, in the case of aluminothermic welding, by the process supplier (3.2)

company approved by the railway authority (3.1) to provide staff and machinery in order to execute the

person who is trained and competent to undertake the appropriate welding machine operation

person who is trained, qualified, approved and competent to carry out inspection of welded joints (3.13)

by observation and judgement, accompanied as appropriate by measurement and testing techniques

butt welding work to connect rails for rail transport operation, whether performed in-factory or on-site

operation by which the rail head or relevant part of the rail head at the welded joint (3.13) is returned to

Note 1 to entry: Operation can be carried out by grinding, milling, planing or any other suitable means.

application of heating and cooling control to a welded joint (3.13) after welding

part of the unmelted base metal where the metal structure, metallurgical properties, mechanical

properties are transformed due to heat input during the welding process such as welding, post-weld

rail joints bonded by welding, which includes the weld metal and the heat-affected zone (3.12)

application of technical methods to examine materials or components in ways that do not impair their

future usefulness and serviceability, in order to detect, locate and evaluate defects, to assess integrity,

acceptance inspection conducted from the viewpoint of quality control targeting welded joints (3.13)

The following processes are currently applied for butt welding connecting rail ends:

a) FBW: Hot pressure welding process using electric current and axial force to produce a welded joint

b) GPW: Hot pressure welding process using gas flame and axial force to produce a welded joint.

c) ATW: Cast fusion welding process using aluminothermic reaction to generate liquid steel.

d) EAW: Electric arc welding process performed by surrounding rails with copper or ceramic block.

a) Preparatory stage: Including provision of information from the railway authority or delegated

b) Working stage: Including rail end preparation, alignment, step treatment, welding work and post-

d) Verification/acceptance stage: Including the tests/inspections classified in Clauses 6 and 7.

NOTE Further details on each stage of each applied process will be prescribed in the subsequent parts of the

Initial approval/homologation tests shall be carried out for every application of each rail welding

process. Approval/homologation tests are used to confirm the reliability of the welding process

and do not reflect quality control in production. Approval/homologation tests shall be carried out

for a particular rail profile and grade, using a specific welding machine or specific type of welding

NOTE The series and sequence of tests for each welding process, together with the number of specimens for

The specification requirements of each approval/homologation test shall be provided to the contractor

After the VT, further appropriate NDT methods shall be applied in accordance with the relevant annexes

of this document and the subsequent parts of the ISO 23300 series, and shall be used to inspect the

The NDT methods for sectioned and full-size samples are dependent upon the welding process being

NOTE The NDT methods for sectioned and full-size samples are described in the subsequent parts of the

The slow-bending test for a welded joint is a practical and efficient test method that can simply evaluate

the performance of the welded joint on whether the load and the deflection satisfy the specified value.

However, the original purpose of the test is to force failure of the welded joint and to observe the

a) one with the rail head upwards in which tensile stress is applied to the rail foot;

b) one with the rail head downwards in which tensile stress is applied to the rail head.

Each slow-bending test shall also be continued until the load or deflection reaches the specified value

For applying the slow-bending test in which tensile stress is applied to the rail foot, the requirements

For applying the slow-bending test in which tensile stress is applied to the rail head, the requirements

The straightness of the welded joint in finished condition shall not affect the execution of a past-the-

The test sample shall be subject to NDT, which shall include VT and UT, MT or PT as appropriate. Only

The test shall be conducted in three-point or four-point bending with the rail foot in tension. Each test

The requirements for the three-point bending test and the test method given in Annex C shall be

The requirements for the four-point bending test and the test method given in Annex D shall be followed.

Macro examination shall be performed to investigate the presence or absence of defects in the relevant

sections, or on a fracture face following bend, fatigue or drop-hammer testing that is not identified as

a surface breaking defect in the welded joint and to confirm that the appropriate heat input has been

Micro examination shall be performed to investigate the presence or absence of an abnormal

metallographic structure in the welded joint. The micro structures depend on each welding process.

A hardness test shall be performed to evaluate wear resistance and to confirm accordance with

A railway authority may demand a drop-hammer test to assess the welded joint’s performance.

Test result reports shall contain, as a minimum, items in accordance with the relevant annexes and

Documentation and records relating to traceability shall be made available upon request by the railway

Prior to any inspection, the welded joint shall be completed and the traceability shall be identified. The

Joints welded in a fixed plant shall be inspected in the plant. Based on the inspection, the welded joint

Joints welded on-site shall be inspected on the railway track. Based on the inspection, the welded joint

shall be deemed as accepted or rejected. This is applicable to FBW using a mobile machine, GPW, ATW

The equipment used for inspection shall be calibrated and shall meet the requirements of the relevant

The inspector shall be competent and shall meet the requirements of the railway authority.

A weld inspection report containing the result and details of the weld inspection shall be completed.

When the inspection results do not conform to this document or the subsequent parts of the ISO 23300

b) NDT (VT shall be applied to find the surface breaking defect about the welded joint. Other inspection

items are optional, and shall be defined by the railway authority. If applicable, Annexes J, K and L

The straightness of the welded joint in finished condition shall be measured, vertically and horizontally

The straightness shall be measured while the welded joint is at ambient temperature. In some specific

cases (i.e. immediately following profiling, insufficient cooling times for site-made welded joints), any

measurement of alignment can be made while the welded joint is hot. The effect of temperature on the

Straightness across the welded joint shall be measured as follows (see Figure 1):

a) The vertical straightness of the running surface shall be measured along the longitudinal surface

of the rail. Measurement points are shown in Figures 1 a) and b). For negative tolerance, see

b) The horizontal straightness of the welded joint at the running edge shall be measured on one or

both faces at a gauge measuring point below the running surface. Measurement points are shown

in Figures 1 c) and d). For negative tolerance which widens the gauge, see Figure 1 c). For positive

c) The necessity of measurement on the field side shall be confirmed by the railway authority with

d) The means of measuring the straightness of the welded joint as described shall be the choice of the

contractor, but in the case of acceptance inspection a calibrated straight edge shall be used.

Acceptance criteria for straightness shall be specified by the railway authority.

a vertical straightness tolerance on the running surface (a is negative tolerance)

a vertical straightness tolerance on the running surface (a is positive tolerance)

Documentation shall contain traceability of the welded joint and inspection reports in accordance with

The welding contractor shall maintain a management system of rail welding that complies with the

The welding contractor shall maintain a system that ensures the competence of employed welders,

welding operators and inspectors through appropriate training, assessment and authorization, and