BS EN 16729-2:2020 pdf free download – Railway applications一Infrastructure 一 Non-destructive testing on rails in track Part 2: Eddy current testing of rails in track.
A.2.4 Verification procedure for assessment of the test system
A.2.4.1 General
The eddy current system to be assessed shall inspect both reference tracks. Reference track number 1 shall be tested for a minimum of one pass in each direction. For reference track number 2, a minimum of two passes is required.
The eddy current system should operate at the normal inspection speed. Check list for verification of the system:
— detectability;
— reproducibility;
— sizing;
— track location;
— evidence of continuous system service;
— all probes operating;
— periodical adjustment.
The system configuration shall stay unchanged during the testing process.
A.2.4.2 Evaluation of verification results for reference track 1
A.2.4.2.1 General
The verification criteria shall be defined by the IM. The following criteria are important for the accuracy of eddy current rail inspection for detecting and sizing head checks:
— Criterion 1: Detectability;
— Criterion 2: Reproducibility;
— Criterion 3: Evaluation of reported maximum depth to be machined d’max.
A.2.4.2.2 Criterion 1: Detectability
Detectability of the eddy current test system represents the capability of the system to discover existing defects.
A.2.4.3 Criteria for the results of the verification for reference track 2
A.2.4.3.1 Approach to evaluate results of reference track 2
As head checks are not isolated cracks and typically affect a larger section of rail (e.g. the outer rail of an entire curve), the focus shall be directed towards these sections in reference track 2. In order to standardize the identification of such sections in reference track 2, clusters shall be identified and assessed using the following rules.
A.2.4.3.2 Rules to identify clusters
The identification is based upon 3 rules which are applied on reported maximum depth to be machined d’max of each metre segment.
— rule #1: A cluster ends when there are 20 one-meter segments or more with d’iiax = 0;
— rule #2: If rule #1 is met, the minimum number of metre segments with d’max> 0 in a cluster is 15 metre segments;
— rule #3: A minimum of 30 % of the cluster shall have a d’max> 0.
If all three rules are met, a cluster is confirmed.
— Conclusion: the minimum number of 15 one-meter segments is exceeded, therefore the criteria of rule #2 is confirmed.
Application of rule #3:
— Between 33, 374 km and 33, 433 km, 17 out of 60 (17 : 60 = 28 %) metre segments are reported with d’max> 0.
Conclusion: the minimum density of 30 % metre segments with d’max> 0 within the cluster is not exceeded, therefore the requirements are not met.
The criteria of rules #1 and #2 are met, but the criteria of rule #3 is not fulfilled. Therefore, no cluster is present between 33, 370 km and 33, 440 km.
A.2.4.3.5 Rule to determine the cluster depth
Based on the reported maximum depth to be machined d’niax of each metre segment of the cluster, the representative depth dncdjaj’i of the cluster shall be determined using the following rule:
— The representative cluster depth dmedian is the median value of the segments with d’max> 0.