ISO/TC 44/SC 5/WG 2 - Ultrasonic testing of welds

This document specifies the application of the time-of-flight diffraction (TOFD) technique to the semi- or fully automated ultrasonic testing of fusion-welded joints in metallic materials of minimum thickness 6 mm. It applies to full penetration welded joints of simple geometry in plates, pipes, and vessels, where both the weld and the parent material are low-alloyed carbon steel. Where specified and appropriate, TOFD can 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 (5 920 ± 50) m/s for longitudinal waves and (3 255 ± 30) m/s for transverse waves. It is necessary to take this fact into account when testing materials with a different velocity. This document makes reference to ISO 16828 and provides guidance on the specific capabilities and limitations of TOFD for the detection, location, sizing and characterization of discontinuities in fusion-welded joints. TOFD can be used as a stand-alone method or in combination with other non-destructive testing (NDT) methods or techniques, for manufacturing inspection, and for in-service inspection. This document specifies four testing levels (A, B, C, D) in accordance with ISO 17635 and corresponding to an increasing level of testing reliability. Guidance on the selection of testing levels is provided. This document permits assessment of TOFD 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.

This document specifies the application of the phased array technology for the semi- or fully automated ultrasonic testing of fusion-welded joints in metallic materials of minimum thickness 6 mm. It applies to full penetration welded joints of simple geometry in plates, pipes, and vessels, where both the weld and the parent material are low-alloy and/or fine grained steel. For the testing of welds in other steel materials this document gives guidance. For coarse-grained or austenitic steels, ISO 22825 applies in addition to this document. This document provides guidance on the specific capabilities and limitations of the phased array technology for the detection, location, sizing and characterization of discontinuities in fusion-welded joints. Phased array technology can be used as a stand-alone technology or in combination with other non-destructive testing (NDT) methods or techniques, for manufacturing inspection, pre-service and for in-service inspection. This document specifies four testing levels, each corresponding to a different probability of detection of imperfections. This document permits assessment of discontinuities for acceptance purposes based either on amplitude (equivalent reflector size) and length, or on height and length. This document does not include acceptance levels for discontinuities. This document is not applicable for automated testing of welds during the production of steel products covered by ISO 10893-8, ISO 10893-11 and ISO 3183.

This document specifies the application of phased array technology for the semi- or fully automated ultrasonic testing of fusion-welded joints in steel parts with thickness values between 3,2 mm and 8,0 mm. This meets the typical range of tube wall thickness values in boilers, which is an important application of this testing technology. The minimum and maximum value of the wall thickness range can be exceeded, when testing level "D" of this document is applied. This document applies to full penetration welded joints of simple geometry in plates, tubes, pipes, and vessels, where both the weld and parent material are low-alloy and/or fine grained steel. NOTE "Semi-automated testing" encompasses a controlled movement of one or more probes on the surface of a component along a fixture (guidance strip, ruler, etc.), whereby the probe position is unambiguously measured with a position sensor. The probe is moved manually. "Fully automated testing" includes mechanized propulsion in addition. Where material-dependent ultrasonic parameters are specified in this document, they are based on steels having a sound velocity of (5 920 ± 50) m/s for longitudinal waves, and (3 255 ± 30) m/s for transverse waves. It is necessary to take this fact into account when testing materials with a different velocity. This document provides guidance on the specific capabilities and limitations of phased array technology for the detection, location, sizing and characterization of discontinuities in fusion-welded joints. Ultrasonic phased array technology can be used as a stand-alone technique or in combination with other non-destructive testing (NDT) methods or techniques, during manufacturing and testing of new welds/repair welds (pre-service testing). This document specifies two testing levels: — level "C" for standard situations; — level "D" for different situations/special applications. This document describes assessment of discontinuities for acceptance purposes based on: — height and length; — amplitude (equivalent reflector size) and length; — go/no-go decision. This document does not include acceptance levels for discontinuities.

This document specifies techniques for the manual ultrasonic testing of fusion-welded joints in metallic materials of thickness ≥8 mm which exhibit low ultrasonic attenuation (especially that due to scatter) at object temperatures from 0 °C to 60 °C. It is primarily intended for use on full penetration welded joints where both the welded and parent material are ferritic. Where material-dependent ultrasonic values are specified in this document, they are based on steels having an ultrasonic sound velocity of (5 920 ± 50) m/s for longitudinal waves and (3 255 ± 30) m/s for transverse waves. This document specifies four testing levels, each corresponding to a different probability of detection of imperfections. Guidance on the selection of testing levels A, B, and C is given in Annex A. This document specifies that the requirements of testing level D, which is intended for special applications, be in accordance with general requirements. Testing level D can only be used when defined by specification. This includes tests of metals other than ferritic steel, tests on partial penetration welds, tests with automated equipment, and tests at object temperatures outside the range 0 °C to 60 °C. This document can be used for the assessment of discontinuities, for acceptance purposes, by either of the following techniques: a) evaluation based primarily on length and echo amplitude of the discontinuity; b) evaluation based on characterization and sizing of the discontinuity by probe movement techniques.

This document specifies acceptance levels for the time‑of‑flight diffraction technique (TOFD) of full penetration welds in ferritic steels from 6 mm up to 300 mm thickness which correspond to the quality levels of ISO 5817. These acceptance levels are applicable to indications classified in accordance with ISO 10863.

ISO 11666:2018 specifies two ultrasonic acceptance levels known as acceptance level 2 (AL 2) and acceptance level 3 (AL 3) for full penetration welded joints in ferritic steels, which correspond to ISO 5817:2014, quality levels B and C. An acceptance level corresponding to ISO 5817:2014, quality level D is not included in this document, as ultrasonic testing is generally not requested for this weld quality. These acceptance levels are applicable to testing carried out in accordance with ISO 17640. ISO 11666:2018 applies to the testing of full penetration ferritic steel welds, with thicknesses from 8 mm to 100 mm. It can also be used for other types of welds, materials and thicknesses, provided the tests have been performed with necessary consideration of the geometry and acoustic properties of the component, and an adequate sensitivity can be employed to enable the acceptance levels of this document to be applied. The nominal frequency of probes used in this document is between 2 MHz and 5 MHz, unless attenuation or requirements for higher resolution call for other frequencies. It is important to consider the use of these acceptance levels in conjunction with frequencies outside this range carefully.

ISO 22825:2017 specifies the approach to be followed when developing procedures for the ultrasonic testing of the following welds: - welds in stainless steels; - welds in nickel-based alloys; - welds in duplex steels; - dissimilar metal welds; - austenitic welds. The purposes of the testing can be very different, for example: - for the assessment of quality level (manufacturing); - for the detection of specific discontinuities induced in service. Acceptance levels are not included in ISO 22825:2017, but can be applied in accordance with the scope of the testing (see 4.1). The requirements of ISO 22825:2017 are applicable to both manual and mechanized testing.

ISO 19285:2017 specifies acceptance levels for the phased array ultrasonic testing technique (PAUT) of full penetration welds in ferritic steels of minimum thickness of 6 mm which correspond to the quality levels of ISO 5817. These acceptance levels are applicable to indications classified in accordance with ISO 13588.

ISO 23279:2017 specifies how to characterize indications from discontinuities by classifying them as originating from planar or non-planar embedded discontinuities. This procedure is also suitable for indications from discontinuities that break the surface after removal of the weld reinforcement.

ISO 17635:2016 gives guidelines for the choice of non-destructive testing (NDT) methods for welds and evaluation of the results for quality control purposes, based on quality requirements, material, weld thickness, welding process and extent of testing. ISO 17635:2016 also specifies general rules and standards to be applied to the different types of testing, for either the methodology or the acceptance levels for metallic materials. Acceptance levels cannot be a direct interpretation of the quality levels defined in ISO 5817 or ISO 10042. They are linked to the overall quality of the produced batch of welds. Requirements for acceptance levels for NDT comply with quality levels stated in ISO 5817 or ISO 10042 (moderate, intermediate, stringent) only on a general basis and not in detail for each indication. Annex A gives correlations between quality, NDT and acceptance level standards. Annex B gives an overview of the standards linked to quality levels, acceptance levels and NDT methods.

ISO 5173:2009 specifies a method for making transverse root, face and side bend tests on test specimens taken from butt welds, butt welds with cladding (subdivided into welds in clad plates and clad welds) and cladding without butt welds, in order to assess ductility and/or absence of imperfections on or near the surface of the test specimen. It also gives the dimensions of the test specimen. In addition ISO 5173:2009 specifies a method for making longitudinal root and face bend tests to be used instead of transverse bend tests for heterogeneous assemblies when base materials and/or filler metal have a significant difference in their physical and mechanical properties in relation to bending. ISO 5173:2009 applies to metallic materials in all forms of product with welded joints made by any fusion arc welding process.

ISO 17640:2017 specifies techniques for the manual ultrasonic testing of fusion-welded joints in metallic materials of thickness ≥8 mm which exhibit low ultrasonic attenuation (especially that due to scatter) at object temperatures from 0 °C to 60 °C. It is primarily intended for use on full penetration welded joints where both the welded and parent material are ferritic. Where material-dependent ultrasonic values are specified in ISO 17640:2017, they are based on steels having an ultrasonic sound velocity of (5 920 ± 50) m/s for longitudinal waves and (3 255 ± 30) m/s for transverse waves. ISO 17640:2017 specifies four testing levels, each corresponding to a different probability of detection of imperfections. Guidance on the selection of testing levels A, B, and C is given in Annex A. ISO 17640:2017 specifies that the requirements of testing level D, which is intended for special applications, be in accordance with general requirements. Testing level D can only be used when defined by specification. This includes tests of metals other than ferritic steel, tests on partial penetration welds, tests with automated equipment, and tests at object temperatures outside the range 0 °C to 60 °C. ISO 17640:2017 can be used for the assessment of discontinuities, for acceptance purposes, by either of the following techniques: a) evaluation based primarily on length and echo amplitude of the discontinuity; b) evaluation based on characterization and sizing of the discontinuity by probe movement techniques.