CEN/TC 138 - Non-destructive testing

This document specifies the general principles for the ultrasonic testing of industrial products that permit the transmission of ultrasound.
The specific conditions of application and use of ultrasonic testing, which depend on the type of product to be tested, are described in documents which can include:
—     product standards;
—     specifications;
—     codes;
—     contractual documents;
—     written procedures.
This document specifies the minimum applicable requirements, unless otherwise specified in the referencing documents.
This document does not specify:
—     extent of testing and scan plans;
—     acceptance criteria.
This document describes only conventional probes, however, the general principles for ultrasonic testing also apply to ultrasonic testing using array techniques. If array techniques are used, then additional steps or verifications can be needed.

This document defines terms used in the field of computed tomography (CT). It presents vocabulary that is not only CT-specific but which also includes other more generic terms and definitions spanning imaging and radiography. Some of the definitions represent discussion points aimed at refocusing their terms in the specific context of computed tomography.

This document specifies characterization tests to be performed at the end of the fabrication of an array probe. It defines both methodology and acceptance criteria.
This document is applicable to the following array probes used for ultrasonic non-destructive testing [phased array technique or signal processing technique, e.g. full-matrix capture (FMC) and total-focusing technique (TFM)] in contact technique (with or without a wedge or delay line) or in immersion technique, with centre frequencies in the range 0,5 MHz to 10 MHz:
a)       array probes with elements in one direction:
—    1-D-linear array (linear array);
—    1-D-curved array;
—    annular array;
b)       array probes with elements in two directions:
—    2-D-array (matrix array);
—    sectorial annular array;
—    partial sectorial annular array.
This document does not give methods and acceptance criteria to characterize the performance of an ultrasonic phased array instrument or the performance of a complete system, which are given in ISO 18563–1 and in ISO 18563–3.

The document specifies requirements for the dimensions, material and manufacture of a steel
block for calibrating ultrasonic test equipment used in ultrasonic testing with the phased array
technique

This document specifies the general principles required for leak detection by acoustic emission testing (AT). It is addressed to the application of the methodology on structures and components, where a leak flow as a result of pressure differences appears and generates acoustic emission (AE).
It describes phenomena of the AE generation and influence of the nature of fluids, shape of the gap, wave propagation and environment.
The different application techniques, instrumentation and presentation of AE results are discussed. Also included are guidelines for the preparation of application documents which describe specific requirements for the application of the acoustic emission testing.
Annex A gives procedures for some leak-testing applications.

This document specifies the requirements for the dimensions, material, and manufacture of a steel step wedge standard block for the setting of an ultrasonic instrument.

This document addresses ultrasonic test systems implementing array probes, for contact technique (with or without wedge) or for immersion technique, with centre frequencies in the range of 0,5 MHz to 10 MHz.
This document provides methods and acceptance criteria for determining the compliance of the complete system (see 3.2). Its purpose is for the verification of the correct operation of the system prior to testing or verification of the absence of degradation of the system.
The methods are not intended to prove the suitability of the system for particular applications but are intended to prove the capability of the complete system (used for an application) to operate correctly according to the settings used. Tests can be performed on individual ultrasonic beams (for phased array technique, see 9.4.4) or on resulting images (for phased array technique and total focusing technique, see 9.4.3).
The tests can be limited to the functions that are intended to be used for a certain application.
This document does not cover the sensitivity setting of the system for a specific application. Nor does it apply to the characterization or verification of the mechanical scanning equipment. It is intended that these items will be covered by the test procedure.
This document does not address the phased array technique using tandem technique.
The characterization of beams, as recommended in case of dead elements or for more in-depth knowledge of the beams, is presented in Annex A. It is not applicable for signal processing technology using arrays.
NOTE            Unless stated otherwise, in this document ‘TFM’ and ‘TFM technique’ refer to the total focusing technique as defined in ISO 23243, and to related techniques, see for example ISO 23865 and ISO 23234.

The function of an industrial radiographic illuminator is to provide sufficient diffuse light for viewing of developed radiographic films (radiographs).
This document specifies the minimum requirements for industrial radiographic illuminators used for viewing radiographs.

This document specifies general requirements for in-service acoustic emission (AE) monitoring. It relates to detection, location and grading of AE sources with application to metallic pressure equipment and other structures such as bridges, bridge ropes, cranes, storage tanks, pipelines, wind turbine towers, marine applications, offshore structures. The monitoring can be periodic, temporary or continuous, on site or remote-controlled, supervised or automated. The objectives of AE monitoring are to define regions which are acoustically active as a result of damage or defect evolution.

This document specifies a method and establishes guidelines for non-destructive testing using active thermography with laser excitation.
Active thermography with laser excitation is mainly applicable, but not limited, to different materials (e.g. composites, metals, ceramics) and to:
- the detection of surface-breaking discontinuities, particularly cracks;
- the detection of discontinuities located just below the surface or below coatings with an efficiency that diminishes rapidly with a few mm depth;
- the detection of disbonds and delamination parallel to the examined surface;
- the measurement of thermal material properties, like thermal diffusivity;
- the measurement of coating thickness.
The requirements for the equipment, for the verification of the system, for the surface condition of the test object, for the scanning conditions, for the recording, the processing and the interpretation of the results are specified. This document does not apply to the definition of acceptance criteria.
Active thermography with laser excitation can be applied in industrial production as well as in maintenance and repair (vehicle parts, engine parts, power plant, aerospace, etc.).

This document specifies the requirements for the dimensions, material, manufacture and methods of use for calibration block No. 2 for setting and checking ultrasonic test equipment.

This document specifies requirements for the qualification and certification of personnel who perform industrial non-destructive testing (NDT) in the following methods.
a) acoustic emission testing;
b) eddy current testing;
c) leak testing (hydraulic pressure tests excluded);
d) magnetic testing;
e) penetrant testing;
f) radiographic testing;
g) strain gauge testing;
h) thermographic testing;
i) ultrasonic testing;
j) visual testing (direct unaided visual tests and visual tests carried out during the application of another NDT method are excluded).
The system specified in this document is also applicable to other NDT methods or to NDT techniques within an established NDT method, provided a comprehensive scheme of certification exists and the NDT method or NDT technique is covered by international, regional or national standards or the NDT method or the NDT technique has been demonstrated to be effective to the satisfaction of the certification body.
NOTE 1    The term "industrial" implies the exclusion of applications in the field of medicine.
NOTE 2    CEN/TR 14748 provides guidance on the methodology for qualification of non-destructive tests.
NOTE 3    This document specifies requirements for what are, in effect, third party conformity assessment schemes. These requirements do not directly apply to conformity assessment by second or first parties, but relevant parts of this document can be referred to in such arrangements.
NOTE 4    The term “direct unaided visual testing” implies where there is an uninterrupted optical path from the observer’s eye to the test area and the observer uses no tools or devices (e.g. mirror, endoscope, fibre optic).
NOTE 5    Calculations of strain based on other NDT methods are excluded.

This document specifies the functional characteristics of multi-channel ultrasonic phased array instruments used for array probes and provides methods for their measurement and verification.
This document is also applicable to ultrasonic phased array instruments in automated systems; but other tests can be needed to ensure satisfactory performance. When the phased array instrument is a part of an automated system, the acceptance criteria can be modified by agreement between the parties involved.
This document also can partly be applicable to FMC instruments and TFM instruments.
This document gives the extent of the verification and defines acceptance criteria within a frequency range of 0,5 MHz to 10 MHz.

This document specifies test routines for the periodic verification of the performance of acoustic emission (AE) test equipment, i.e. sensors, pre-amplifiers, signal processors, external parametric inputs.
It is intended for use by qualified personnel to implement an automated verification process.
Verification of the measurement characteristics is advised after purchase of equipment, in order to obtain reference data for later verifications. Verification is also advised after repair, modifications, use under extraordinary conditions, or if one suspects a malfunction.
The procedures specified in this document do not exclude other qualified methods, e.g. verification in the frequency domain. These procedures apply in general unless the manufacturer specifies alternative equivalent procedures.
Safety aspects of equipment for use in potentially explosive zones are not considered in this document.

This document specifies the application of the time-of-flight diffraction (TOFD) technique in testing of metals for quantifying loss of thickness due to erosion and/or corrosion.
This document applies to all types of corrosion and/or erosion damage, particularly those defined in EN ISO 16809.
This document applies to unalloyed or low-alloyed steels.
It applies to components with a nominal thickness ≥ 6 mm. For smaller thicknesses, feasibility tests are performed to validate the test technique.
For other materials, feasibility tests are essential, too.
The TOFD technique can be used as a stand-alone technique or in combination with other non-destructive testing techniques, for in-service testing, in order to detect material loss caused by erosion and/or corrosion.
This technique is based on analysis of TOFD images using reflected and/or diffracted ultrasonic signals.
This document does not specify acceptance levels.

This document specifies the technical requirements and test procedures for penetrant materials for their type testing and batch testing. This document covers the temperature range from 10 °C to 50 °C. Additional tests in ISO 3452-5 or ISO 3452-6 can be required outside this range.
On-site control tests and methods are detailed in ISO 3452‑1.

This document specifies a method of penetrant testing used to detect discontinuities, e.g. cracks, laps, folds, porosity and lack of fusion, which are open to the surface of the material to be tested using white light or UV-A (365 nm) radiation. It is mainly applied to metallic materials, but can also be performed on other materials, provided that they are inert to the test media and not excessively porous (castings, forgings, welds, ceramics, etc.)
This document also includes requirements for process and control testing, but is not intended to be used for acceptance criteria. It gives neither information relating to the suitability of individual test systems for specific applications nor requirements for test equipment.
NOTE 1   Methods for determining and monitoring the essential properties of penetrant testing products to be used are specified in ISO 3452-2 and ISO 3452-3.
NOTE 2   The term "discontinuity" is used in this document in the sense that no evaluation concerning acceptability or non-acceptability is included.
NOTE 3   CEN/TR 16638 addresses penetrant testing using actinic blue light.

This document specifies a method for the measurement of effective focal spot dimensions above 0,1 mm of X-ray systems up to and including 1000 kV tube voltage by means of the pinhole camera method with digital evaluation. The tube voltage applied for this measurement is restricted to 200 kV for visual film evaluation and may be selected higher than 200 kV if digital detectors are used.
The imaging quality and the resolution of X-ray images depend highly on the characteristics of the effective focal spot, in particular the size and the two dimensional intensity distribution as seen from the detector plane. This method compared to the others in the EN 12543 series allows to obtain an image of the focal spot and to see the state of it (e.g. cratering of the anode).
This test method provides instructions for determining the effective size (dimensions) of standard (macro focal spots) and mini focal spots of industrial X-ray tubes. This determination is based on the measurement of an image of a focal spot that has been radiographically recorded with a "pinhole" technique and evaluated with a digital method.
For the characterization of commercial X-ray tube types (i.e. for advertising or trade) it is advised that the specific FS (Focal spot) values of Annex A are used.

This document defines terms used in ultrasonic testing with arrays. This includes phased array technology and signal processing technology using arrays, e. g. the full-matrix capture (FMC) (3.3.1.28) and the total focusing technique (TFM) (3.3.1.35).

This document specifies methods, tolerances and acceptance criteria for verifying the performance of combined ultrasonic test equipment (i.e. instrument, probes and cables connected) by the use of appropriate standard calibration blocks.
These methods are specifically intended for manual test equipment, i.e. ultrasonic instruments according to ISO 22232-1, and for manual ultrasonic non-destructive testing with single- or dual-transducer probes according to ISO 22232-2. This document is also applicable for multi-channel instruments. For automated test equipment, different tests can be needed to ensure satisfactory performance.
The specified methods are intended for the use by operators working under site or shop floor conditions.
These methods are not intended to prove the suitability of the equipment for particular applications.
This document excludes ultrasonic instruments for continuous waves.
This document also excludes ultrasonic phased array systems, see e. g. ISO 18563-3. If a phased array instrument is used in combination with single- or dual-transducer probes, this document is applicable to this combination.

This document specifies the characteristics of probes used for non-destructive ultrasonic testing in the following categories with centre frequencies in the range of 0,5 MHz to 15 MHz, focusing or without focusing means:
a)   single- or dual-transducer contact probes generating longitudinal and/or transverse waves;
b)   single-transducer immersion probes.
Where material-dependent ultrasonic values 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.
This document excludes periodic tests for probes. Routine tests for the verification of probes using on-site procedures are given in ISO 22232-3.
If parameters in addition to those specified in ISO 22232-3 are to be verified during the probe's life time, as agreed upon by the contracting parties, the procedures of verification for these additional parameters can be selected from those given in this document.
This document also excludes ultrasonic phased array probes, therefore see ISO 18563-2.

This document describes the test method for determining residual stresses in polycrystalline materials by neutron diffraction. It is applicable to both homogeneous and inhomogeneous materials including those containing distinct phases.
The principles of the neutron diffraction technique are outlined. Suggestions are provided on:
—          the selection of appropriate diffracting lattice planes on which measurements should be made for different categories of materials,
—          the specimen directions in which the measurements should be performed, and
—          the volume of material examined in relation to the material grain size and the envisaged stress state.
Procedures are described for accurately positioning and aligning test pieces in a neutron beam and for precisely defining the volume of material sampled for the individual measurements.
The precautions needed for calibrating neutron diffraction instruments are described. Techniques for obtaining a stress-free reference are presented.
The methods of making individual measurements by neutron diffraction are described in detail. Procedures for analysing the results and for determining their statistical relevance are presented. Advice is provided on how to determine reliable estimates of residual stresses from the strain data and on how to estimate the uncertainty in the results.

This document specifies methods and acceptance criteria within the frequency range of 0,5 MHz to 15 MHz, for assessing the electrical performance of digital ultrasonic instruments for pulse operation using A-scan display, for manual ultrasonic non-destructive testing with single- or dual-transducer probes. This document is also applicable for multi-channel instruments. This document can partly be applicable to ultrasonic instruments in automated systems, but other tests can be needed to ensure satisfactory performance.
This document excludes ultrasonic instruments for continuous waves.
This document also excludes ultrasonic phased array instruments, see e.g. ISO 18563-1. If a phased array instrument has dedicated connectors for single- or dual-transducer probes this document is applicable for these channels.

ISO 14096-2:2005 specifies three film-digitisation quality classes for the requirements of non-destructive testing. The selected class depends on the radiation energy, penetrated material thickness and the quality level of the original radiographic film. ISO 14096-2:2005 does not address signal processing, display and storage of the digitised data.

ISO 14096-1:2005 specifies procedures for the evaluation of basic performance parameters of the radiographic film digitisation process such as spatial resolution and spatial linearity, density range, density contrast sensitivity and characteristic transfer curve. They can be integrated into the system software and together with a standard reference film used for quality control of the digitisation process. This reference film provides a series of test targets for performance evaluation. The test targets are suitable for evaluating a digitisation system with a spatial resolution down to 25 micrometres, a density contrast sensitivity down to 0,02 optical density, a density range of 0,5 to 4,5 and a film size capacity of (350 x 430) mm2. This standard does not address signal processing and display of the digitised data.

ISO 16526-2:2011 specifies a constancy check of a X-ray system where mainly the X-ray voltage is checked and also the tube current and the constitution of the target which can be changing due to ageing of the tube.
The thick filter method is based on a measurement of the dose rate behind a defined thick filter using defined distances between the X-ray tube, the filter and the measuring device.
This method is very sensitive to changes of the voltage, but it does not provide an absolute value for the X-ray tube voltage. Therefore, a reference value is needed and, it is recommended to find this reference, for example, within the acceptance test of the system.
The thick filter method is a rather simple technique and may be applied by the operator of an X-ray system to perform regularly a constancy check of the system.
The method can also be applied for consistency checks after changing components which may affect the X-ray tube voltage.
This method can be applied for all types of X-ray systems, i. e. for constant potential, half wave and impulse wave generators with a tube current larger than 1 mA.

ISO 16526-1:2011 specifies a method for the direct and absolute measurement of the average high voltage of constant potential (DC) X-ray systems on the secondary side of the high voltage generator. The intention is to check the correspondence with the indicated high voltage value on the control unit of the X-ray system.
This method is applied to assure a reproducible operation of X-ray systems because the voltage influences particularly the penetration of materials and the contrast of X-ray images and also the requirements concerning the radiation protection.

ISO 16526-3:2011 specifies the test method for a non-invasive measurement of X-ray tube voltages using the energy spectrum of X-rays (spectrometric method). It covers the voltage range from 10 kV to 500 kV.
The intention is to check the correspondence of the actual voltage with the indicated value on the control panel of the X-ray unit. It is intended to measure the maximum energy only and not the complete X-ray spectrum.
The procedure is applicable for tank type and constant potential X-ray units.

This document defines terms used in eddy current testing.

ISO 16809:2017 specifies the principles for ultrasonic thickness measurement of metallic and non-metallic materials by direct contact, based on measurement of time of flight of ultrasonic pulses only.

This document defines the general principles to be applied to non-destructive eddy current examination of products and materials in order to ensure defined and repeatable performance.
It includes guidelines for the preparation of application documents which describe the specific requirements for the application of the eddy current method to a particular type of product.

ISO 15708-3:2017 presents an outline of the operation of a computed tomography (CT) system and the interpretation of results with the aim of providing the operator with technical information to enable the selection of suitable parameters.
It is applicable to industrial imaging (i.e. non-medical applications) and gives a consistent set of CT performance parameter definitions, including how those performance parameters relate to CT system specifications.
ISO 15708-3:2017 deals with computed axial tomography and excludes other types of tomography such as translational tomography and tomosynthesis.

ISO 15708-2:2017 specifies the general principles of X-ray computed tomography (CT), the equipment used and basic considerations of sample, materials and geometry.
It is applicable to industrial imaging (i.e. non-medical applications) and gives a consistent set of CT performance parameter definitions, including how those performance parameters relate to CT system specifications.
ISO 15708-2:2017 deals with computed axial tomography and excludes other types of tomography such as translational tomography and tomosynthesis.

This document gives requirements and recommendations for non-destructive testing (NDT) training syllabuses, with the intention of harmonizing and maintaining the general standard of training of NDT personnel for industrial needs.
It also establishes the minimum requirements for effective structured training of NDT personnel to ensure eligibility for qualification examinations leading to third-party certification according to recognized standards. In addition to non-destructive testing in general, its guidelines for syllabuses cover acoustic emission testing, eddy current testing, leak testing, magnetic testing, penetrant testing, radiographic testing, ultrasonic testing, visual testing, thermographic testing, and strain gauge testing.
ISO/TS 25108 gives requirements and recommendations for NDT training organizations.

ISO 15708-4:2017 specifies guidelines for the qualification of the performance of a CT system with respect to various inspection tasks.
It is applicable to industrial imaging (i.e. non-medical applications) and gives a consistent set of CT performance parameter definitions, including how those performance parameters relate to CT system specifications.
ISO 15708-4:2017 deals with computed axial tomography and excludes other types of tomography such as translational tomography and tomosynthesis.

This document specifies the determination of the size of gamma radiographic sources of 0,5 mm or greater, made from the radionuclides Iridium 192, Ytterbium 169, Selenium 75 or Cobalt 60, by a method of radiography with X-rays. The source size of a gamma radiography source is an important factor which affects the image quality of gamma ray images.
The source size is determined with an accuracy of ± 10 % but typically not better than ± 0,1 mm.
The source size is provided by the manufacturer as the mechanical dimension of the source insert. A measurement may be required if the manufacturing process is validated or monitored after implementation of the source into the holder.
This document can be used for other radionuclides after validation.
The standard test method ASTM E1114 provides further information on the measurement of the Ir-192 source size, the characterization of the source shape, and its correct assembly and packaging.

This document specifies fundamental techniques of film and digital radiography with the object of enabling satisfactory and repeatable results to be obtained economically. The techniques are based on generally recognized practice and fundamental theory of the subject.
This document applies to the radiographic examination of steel pipes for service induced flaws such as corrosion pitting, generalized corrosion and erosion. Besides its conventional meaning, "pipe" as used in this document is understood to cover other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels.
Weld inspection for typical welding process induced flaws is not covered, but weld inspection is included for corrosion/erosion type flaws.
The pipes can be insulated or not, and can be assessed where loss of material due, for example, to corrosion or erosion is suspected either internally or externally.
This document covers the tangential inspection technique for detection and through-wall sizing of wall loss, including with the source:
a)    on the pipe centre line; and
b)    offset from pipe centre line by the pipe radius.
ISO 20769-2 covers double wall radiography, and note that the double wall double image technique is often combined with tangential radiography with the source on the pipe centre line.
This document applies to tangential radiographic inspection using industrial radiographic film techniques, computed radiography (CR) and digital detector arrays (DDA).

This document specifies fundamental techniques of film and digital radiography with the object of enabling satisfactory and repeatable results to be obtained economically. The techniques are based on generally recognized practice and fundamental theory of the subject.
This document applies to the radiographic examination of pipes in metallic materials for service induced flaws such as corrosion pitting, generalized corrosion and erosion. Besides its conventional meaning, "pipe" as used in this document is understood to cover other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels.
Weld inspection for typical welding process induced flaws is not covered, but weld inspection is included for corrosion/erosion type flaws.
The pipes can be insulated or not, and can be assessed where loss of material due, for example, to corrosion or erosion is suspected either internally or externally.
This document covers double wall inspection techniques for detection of wall loss, including double wall single image (DWSI) and double wall double image (DWDI).
Note that the DWDI technique described in this document is often combined with the tangential technique covered in ISO 20769-1.
This document applies to in-service double wall radiographic inspection using industrial radiographic film techniques, computed digital radiography (CR) and digital detector arrays (DDA).

This document specifies a method of determining the total image unsharpness and basic spatial resolution of radiographs and radioscopic images. The IQI with up to 13 wire pairs can be used effectively with tube voltages up to 600 kV. The IQI with more than 13 wire pairs can be used effectively at tube voltages lower than 225 kV. When using source voltages in the megavolt range, it is possible that the results are not be completely satisfactory.

This document specifies a procedure for the control of film processing systems.

This document defines the procedures for non-destructive testing using active thermography.
These testing procedures can be applied to different materials (e.g. composites, metals and coatings) and are appointed, but not limited to the:
—   detection of discontinuities (e.g. voids, cracks, inclusions, delaminations);
—   determination of layer or part thicknesses;
—   determination and comparison of thermophysical properties.
This standard is describing data acquisition and analysis principles for active thermography and is giving an informative guideline for appropriate selection of the excitation source. Acceptance criteria are not defined in this standard.
Active thermography is applied in industrial production (e.g. compound materials, vehicle parts, engine parts, power plant parts, joining technology, electronic devices) and in maintenance and repair (e.g. aerospace, power plants, civil engineering).

This document gives requirements and recommendations for non-destructive testing (NDT) training organizations, with the intention of harmonizing and maintaining the general standard of training of NDT personnel for industrial needs.
It also establishes the minimum requirements for effective structured training of NDT personnel to ensure eligibility for qualification examinations leading to third-party certification according to recognized standards.
NOTE       ISO/TS 25107 gives requirements and recommendations for NDT training syllabuses intended for training.

ISO 20486:2017 specifies the calibration of those leaks that are used for the adjustment of leak detectors for the determination of leakage rate in everyday use. One type of calibration method is a comparison with a reference leak. In this way, the leaks used for routine use become traceable to a primary standard. In other calibration methods, the value of vapour pressure was measured directly or calculated over a known volume.
The comparison procedures are preferably applicable to helium leaks, because this test gas can be selectively measured by a mass spectrometer leak detector (MSLD) (the definition of MSLD is given in ISO 20484).
Calibration by comparison (see methods A, As, B and Bs below) with known reference leaks is easily possible for leaks with reservoir and leakage rates below 10−7 Pa·m3/s.
Figure 1 gives an overview of the different recommended calibration methods.

ISO 20485:2017 describes the techniques to be applied for the detection of a leak, using a tracer gas and a tracer gas specific leak detector.

ISO 16371-2:2017 specifies fundamental techniques of computed radiography with the aim of enabling satisfactory and repeatable results to be obtained economically. The techniques are based on the fundamental theory of the subject and tests measurements. ISO 16371-2:2017 specifies the general rules for industrial computed X-rays and gamma radiography for flaw detection purposes, using storage phosphor imaging plates (IP). It is based on the general principles for radiographic examination of metallic materials on the basis of films, as specified in ISO 5579. The basic set-up of radiation source, detector and the corresponding geometry are intended to be applied in accordance with ISO 5579 and corresponding product standards such as ISO 17636 for welding and EN 12681 for foundry.
ISO 16371-2:2017 does not lay down acceptance criteria of the imperfections. Computed radiography (CR) systems provide a digital grey value image which can be viewed and evaluated on basis of a computer only. This practice describes the recommended procedure for detector selection and radiographic practice. Selection of computer, software, monitor, printer and viewing conditions are important but not the main focus of ISO 16371-2:2017.
The procedure it specifies provides the minimum requirements and practice to permit the exposure and acquisition of digital radiographs with a sensitivity of imperfection detection equivalent to film radiography and as specified in ISO 5579. Some application standards, e.g. EN 16407, can require different and less stringent practice conditions.

This European Standard is concerned only with terms used specifically in acoustic emission testing (AT) and these fall into four parts:
-   terms relating to the physical phenomenon;
-   terms relating to the detection of the acoustic emission;
-   terms relating to the measured characteristics of the signal(s);
-   terms relating to acoustic emission applications.

ISO 20339:2017 identifies the functional characteristics of eddy current array probes and their interconnecting elements and provides methods for their measurement and verification.
The evaluation of these characteristics permits a well-defined description and comparability of eddy current array probes.
Where relevant, this document gives recommendations for acceptance criteria for the characteristics.

ISO 20484:2017 defines the terms used in leak testing.

This document specifies minimum requirements in order to obtain and reproduce photographs used as reference records relative to PT (penetrant testing) colour contrast and fluorescent indications. It also provides requirements for the monitoring of resolution when measurements are to be indirectly performed by recording.

ISO 5577:2017 defines the terms used in ultrasonic non-destructive testing and forms a common basis for standards and general use. This document does not cover terms used in ultrasonic testing with phased arrays.
NOTE          Terms for phased array ultrasonic testing are defined in EN 16018.