BS EN 16729-2-2020 pdf free download.Railway applications — Infrastructure — Non-destructive testing on rails in track Part 2: Eddy current testing of rails in track
This document is applicable to testing of rails installed in track for detecting rail surface cracks. This document applies to testing equipment in inspection-trains or reprofiling machines and manual systems. This document specifies the requirement for testing principles and systems in order to produce comparable results in respect to the location and the characteristic of surface cracks. This document is not aiming to give any guidelines for managing the result of eddy current rail testing. This document does not define the requirements for vehicle acceptance. This document is not concerned with production testing of rails in a production plant. This document applies only to rail profiles meeting the requirements of EN 13674-1.
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 13231-5, Railway applications — Track — Acceptance of works — Part 5: Procedures for rail reprofiling in plain line, switches, crossings and expansion devices
EN 16729-1:2016, Railway applications — Infrastructure — Non-destructive testing on rails in track —Part 1: Requirements for ultrasonic inspection and evaluation principles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 16729-1:2016 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 real crack
crack caused by traffic loads or production induced
Note 1 to entry: Cracks may also be simulated. They then constitute an artificial feature designed to represent a real defect of a known size, orientation and position.
5 Basic principles
5.1 General
With the help of eddy current testing, surface cracks can be detected in electrically conducting materials (ferromagnetic or non-ferromagnetic materials).
Eddy current testing is based on the induction of electric current in electrically conducting material. The measured and analysed size refers to the distribution of the induced currents (eddy currents).
The distribution of the eddy currents in the material is governed by physical laws; the density of these eddy currents drastically decreases with the distance to the surface.
To determine the depth of a head check crack, the pocket length of the crack and the penetrating angle are used. The penetrating angle can vary depending on steel grade, traffic, tonnage and support conditions of the rail. The penetrating angle α’ (see Figure 3) commonly used for testing head checks in rail is 25 °.
Parameters influencing the testing results are:
— conductivity of the material;
— permeability of the material;
— dimension and geometry of the defect;
— geometry between the eddy current probe and the material surface;
— design and size of the probe;
— setting of the excitation frequency.
More detailed information on the eddy current method can be found in EN ISO 15549.
5.2 Purpose of testing
The purpose of eddy current testing on rails is to detect, quantify or classify rail defects in the material surface mainly due to rolling contact fatigue which can affect the structural integrity of the rails in track and which are defined in EN 13231-5. This is not limited to, but generally covers the following defects:
— head checks;
— squats;
— flaking;
— spalling.
6 Requirements for the eddy current testing system on rails
Inspection of the rail surface can be carried out manually or by using mechanized devices.
When testing with an eddy current probe, it is placed above the rail head. The impedance of the probe is influenced by the interaction of the electromagnetic field generated by the probe and the rail head. This influence recorded by the complex voltage of the probe can be calculated to the severity of cracking on rail surface.
The minimum requirements for a test system are:
— suitable for the test task;
— capable of dealing with various material characteristics (e.g. welds, steel grades);
— probes optimized to the position, direction, depth and distance between cracks;
— probes optimized to test non-planar rail surfaces;
— capable of testing rough and rusty surfaces;
— capable of recording the correct location of the defect;
— capable of testing forwards and backwards in track independent of the direction of the traffic (if mounted on vehicle, independent of the orientation of the vehicle).
NOTE The list does not include the requirements for operational use of the test system in track.BS EN 16729-2 pdf download.