ISO/TC 135/SC 5 - Radiographic testing

This document is used for non-destructive testing by the gamma ray scanning method for troubleshooting and testing process columns in industries. This document is applicable to the testing of all kinds of separation processes columns and pipes. This includes columns with different tray configurations and with packed beds.

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 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 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 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.

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.

ISO 15708-1:2017 gives the definitions of terms used in the field of computed tomography (CT). It presents a terminology 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.

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.

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 15708-4:2017 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.

ISO 5579:2013 outlines the general rules for industrial X- and gamma-radiography for flaw-detection purposes, using film techniques, applicable to the inspection of metallic products and materials. It does not lay down acceptance criteria of the imperfections.

ISO 19232-1:2013 specifies a device and a method for the determination of the image quality of radiographs using wire-type image quality indicators.

ISO 19232-3:2013 specifies the minimum image quality values to ensure a uniform radiographic quality. It applies to the two types of image quality indicator as detailed in ISO 19232-1 for wire-type IQI and ISO 19232-2 for step/hole-type IQI and for the two techniques described in ISO 5579. Values are specified for the two classes of radiographic technique specified in ISO 5579.

ISO 19232-4:2013 gives instructions for the determination of image quality values and image quality tables. If the IQI requirements specified in ISO 19232‑3 cannot be used because, for example, the absorption coefficients of the IQI material and the inspected material differ by more than 30 %, test exposures are necessary to determine acceptance of image quality values. The image quality values achieved by the test exposures are required for all exposures made under the same radiographic conditions.

ISO 19232-2:2013 specifies a device and a method for the determination of the image quality of radiographs using step/hole-type image quality indicators.

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.

ISO 16371-1:2011 specifies fundamental parameters of computed radiography systems with the aim of enabling satisfactory and repeatable results to be obtained economically. The techniques are based both on fundamental theory and test measurements. ISO 16371-1:2011 specifies the performance of computed radiography (CR) systems and the measurement of the corresponding parameters for the system scanner and storage phosphor imaging plate (IP). It describes the classification of these systems in combination with specified metal screens for industrial radiography. It is intended to ensure that the quality of images, as far as this is influenced by the scanner-IP system, is in conformity with the requirements of ISO 16371-2. ISO 16371-1:2011 relates to the requirements of film radiography defined in ISO 11699-1. ISO 16371-1:2011 defines system tests at different levels. More complicated tests are described, which allow the determination of exact system parameters. They can be used to classify the systems of different suppliers and make them comparable for users. These tests are specified as manufacturer tests. Some of them require special tools, which are usually not available in user laboratories. Therefore, simpler user tests are also described, which are designed for a fast test of the quality of CR systems and long term stability. There are several factors affecting the quality of a CR image including geometrical un-sharpness, signal/noise ratio, scatter and contrast sensitivity. There are several additional factors (e.g. scanning parameters), which affect the accurate reading of images on exposed IPs using an optical scanner. The quality factors can be determined most accurately by the manufacturer tests as described in ISO 16371-1:2011. Individual test targets, which are recommended for practical user tests, are described for quality assurance. These tests can be carried out either separately or by the use of the CR Phantom (Annex B). This CR Phantom incorporates many of the basic quality assessment methods and those associated with the correct functioning of a CR system, including the scanner, for reading exposed plates and in correctly erasing IPs for future use of each plate. The CR System classes in ISO 16371-1:2011 do not refer to any particular manufacturer's Imaging Plates. A CR system class results from the use of a particular imaging plate together with the exposure conditions (particularly total exposure), the scanner type and the scanning parameters.

The purpose of ISO 11699-1:2008 is to establish the performance of film systems. ISO 11699-1:2008 is applicable for the classification of film systems in combination with specified lead screens for industrial radiography (non-destructive testing). ISO 11699-1:2008 is intended to ensure that the image quality of radiographs – as far as this is influenced by the film system – is in conformity with the requirements of International Standards such as ISO 5579, ISO 17636 and EN 12681. ISO 11699-1:2008 does not apply to the classification of films used with fluorescent intensifying screens. The measurement of film systems in ISO 11699-1:2008 is restricted to a selected radiation quality to simplify the procedure. The properties of films will change with radiation energy, but not the ranking of film system quality. Additional methods for evaluating the photographic process are described in ISO 11699-2, by which the performance of film systems can be controlled under the conditions given in industry.

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 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.

This International Standard defines an empirical technique for the measurement of the effective collimation ratio and effective L/D of thermal neutron radiography beams for values between 20 and 1 000. The technique is based upon analysis of a neutron radiographic image and is independent of measurements and calculations based on physical dimensions of the collimator system. The device described in this International Standard has been developed and tested using Gd foil converters with a single emulsion, high resolution film in vacuum cassettes.

The function of illuminators is to allow the viewing of radiographs. The illuminator system shall guarantee the same safety of personnel as an electric apparatus concerning maximum voltage, insulation and earthing.

ISO 19232-5:2013 specifies a method of determining the total image unsharpness of radiographs and real-time radioscopic systems.

ISO/TS 21432:2005 gives the standard test method for determining residual stresses in polycrystalline materials by neutron diffraction. It is applicable to homogeneous and inhomogeneous materials and to test pieces containing distinct phases.

ISO 19232-4:2004 gives instructions for the determination of image quality values and image quality tables used in radiographic testing.

ISO 19232-1:2004 specifies a device and a method for the determination of the image quality of radiographs using wire type image quality indicators.

ISO 19232-2:2004 specifies a device and a method for the determination of the image quality of radiographs using step/hole type image quality indicators.

ISO 19232-5:2004 specifies a method of determining the image unsharpness of radiographs and realtime radioscopic systems.

ISO 19232-3:2004 specifies the minimum image quality values to ensure a uniform radiographic quality. It applies to the two types of image quality indicator as detailed in ISO 19232-1 for wire type image quality indicators and ISO 19232-2 for step/hole type image quality indicators as well as for the two techniques described in ISO 5579. Values are specified for both the basic and improved radiographic techniques specified in ISO 5579 and for ferrous metals.

ISO 15708-2 describes CT procedures that can provide for non-destructive testing and evaluation. Requirements in this part of ISO 15708 are intended to control the reliability and quality of the CT images. This part of ISO 15708 is applicable for the systematic assessment of the internal structure of a material or assembly and may be used to prescribe operating CT procedures. It also provides a basis for the formation of a programme for quality control and its continuation through calibration, standardization, reference samples, inspection plans and procedures. ISO 15708-2 gives guidelines for procedures for performing CT examinations. It is intended to address the general use of CT technology and thereby facilitate its use. This part of ISO 15708 implicitly assumes the use of penetrating radiation, specifically X-ray and gamma-ray.

ISO 15708-1 provides a tutorial introduction to the theory and use of computed tomography. It begins with an overview intended for the interested reader possessing a general technical background. Subsequent, more technical clauses describe the physical and mathematical basis of CT technology, the hardware and software requirements of CT equipment, and the fundamental measures of CT performance. This part of ISO 15708 includes an extensive glossary (with discussions) of CT terminology and an extensive list of references to more technical publications on the subject. Most importantly, this part of ISO 15708 establishes consensus definitions for basic measures of CT performance, enabling purchasers and suppliers of CT systems and services to communicate unambiguously with reference to a recognized standard. It also provides a few carefully selected equations relating measures of CT performance to key system parameters. ISO 15708-1 gives guidelines for, and defines terms for addressing the general principles of X-ray CT as they apply to industrial imaging. It also gives guidelines for a consistent set of CT performance parameter definitions, including how these performance parameters relate to CT system specifications.

The detection of an imperfection in a product subjected to X or gamma radiography depends on the quality of the resultant radiograph. This quality should be checked with an image quality indicator. This International Standard is intended for general application on all metals. However, for particular materials (for example, aluminium and its alloys) complementary International Standards may be used.