CEN/TS 14751:2004

Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 General remarks on the capabilities of the technique
5 Examination levels
6 Information required prior to testing
   6.1 Items to be defined by specification
   6.2 Specific information required by the operator
        before testing
   6.3 Written test instruction
7 Requirements for personnel and equipment
   7.1 Personnel qualifications
   7.2 Equipment
        7.2.1 Ultrasonic equipment and display
        7.2.2 Ultrasonic probes
        7.2.3 Scanning mechanisms
8 Preparation for testing
   8.1 Volume to be inspected
   8.2 Set up of probes
   8.3 Scan increment setting
   8.4 Geometry considerations
   8.5 Preparation of scanning surfaces
   8.6 Temperature
   8.7 Couplant
   8.8 Provision of datum points
9 Testing of base material
10 Range and sensitivity settings
   10.1 Settings
        10.1.1 General
        10.1.2 Time window
        10.1.3 Time-to-depth conversion
        10.1.4 Sensitivity settings
   10.2 Checking of the settings
   10.3 Reference blocks
        10.3.1 General
        10.3.2 Material
        10.3.3 Dimensions and shape
        10.3.4 Reference reflectors
11 Weld testing
12 Interpretation and analysis of TOFD images
   12.1 General
   12.2 Assessing the quality of the TOFD image
   12.3 Identification of relevant indications
   12.4 Classification of relevant indications
        12.4.1 General
        12.4.2 Indications from surface breaking
               discontinuities
        12.4.3 Indications from embedded discontinuities
        12.4.4 Unclassified indications
   12.5 Determination of location and size
        12.5.1 Location
        12.5.2 Sizing
   12.6 Evaluation against acceptance criteria
13 Test report
   13.1 General
   13.2 Information relating to object under test
   13.3 Information relating to equipment
   13.4 Information relating to test technique
   13.5 Information relating to test results
Annex A (informative) Reference blocks
   A.1 Thickness requirements
        A.1.1 Maximum thickness
        A.1.2 Minimum thickness
   A.2 Reference reflectors
   A.3 Typical reference blocks
Annex B (informative) Examples of typical scans
   B.1 Satisfactory and unsatisfactory TOFD-images
   B.2 Typical TOFD-images of discontinuities in fusion
        welded joints
   B.3 TOFD-images of geometrical features
Bibliography

This document specifies the application of the time-of-flight diffraction (TOFD) technique for the semi-, or fully- automated ultrasonic testing of fusion welded joints in metallic materials equal to and above 6 mm thickness. It is primarily intended for use on full penetration welded joints of simple geometry in plates, pipes, and vessels, where both the weld and parent material are low alloyed carbon steel. Where specified and appropriate, TOFD may also be used on other types of materials that exhibit low ultrasonic attenuation (especially that due to scatter).Where material dependent ultrasonic parameters are specified in this document, they are based on steels having a sound velocity of (5920 ± 50) m/s for longitudinal waves, and (3255 ± 30) m/s for transverse waves. This has to be taken into account when examining materials with a different velocity.This document makes reference to the basic pre-standard ENV 583 6 and provides guidance on the specific capabilities and limitations of TOFD for the detection, location, sizing and characterisation of discontinuities in fusion welded joints. TOFD may be used as a stand-alone method or in combination with other NDT methods or techniques, both for manufacturing inspection (pre-service) and for in-service inspection.This document specifies four examination levels (A, B, C, D) corresponding to an increasing level of inspection reliability. Guidance on the selection of examination levels is provided.This document permits assessment of indications for acceptance purposes. This assessment is based on the evaluation of transmitted, reflected and diffracted ultrasonic signals within a generated TOFD image. This document does not include acceptance levels for discontinuities.