ISO 18251-1:2017

Overview

ISO 18251-1:2017 is an international standard developed by ISO for non-destructive testing (NDT) using infrared thermography. This standard specifically addresses the characteristics of infrared (IR) imaging systems and associated equipment for industrial applications. By defining the principal components-such as objective lens, detector, image processor, display, thermal stimulation source, and accessories-the document provides essential guidance for selecting, evaluating, and applying IR systems in NDT tasks. The main aim is to assist users in understanding key system features to make informed decisions when deploying IR thermography for inspections, quality assurance, and maintenance.

Key Topics

• Objective Lens: Covers lens types, spectral response (short wave, mid wave, and long wave IR), focal length, aperture f-number, and the importance of interchangeable lenses for tailored measurement tasks.
• Detector: Describes detector types (thermal and quantum), detector arrays, scanning systems, working wavelength ranges, pixel counts, and crucial characteristics such as operability, bad/dead pixels, thermal time constant, and temperature range.
• Image Processor: Details processes for image acquisition, display, analysis, and enhancement, including advanced functions like bad pixel replacement, non-uniformity correction, filtering, and image fusion techniques.
• Thermal Stimulation Source: Outlines energy delivery methods for active thermography, including optical radiation (lasers, lamps), convective devices, electromagnetic induction, and mechanical excitation, along with their respective advantages and limitations.
• Integrated Performance Parameters: Defines critical system metrics such as noise equivalent temperature difference (NETD), minimum resolvable/detectable temperature differences (MRTD/MDTD), field of view (FOV), instantaneous FOV (IFOV), temperature measurement range, and uniformity.
• Accessories: Lists supporting equipment like IR mirrors, attenuation filters, spectral filters, tripods, and reference blocks, enhancing test adaptability and accuracy.

Applications

Infrared thermography, guided by ISO 18251-1:2017, is widely used for non-destructive testing in various industries. Key application areas include:

• Industrial Asset Inspection: Detecting thermal anomalies in mechanical and electrical systems without causing damage to components.
• Quality Control: Identifying manufacturing defects such as delaminations, voids, or cracks in materials and products.
• Preventive Maintenance: Monitoring equipment and infrastructure to predict failures and schedule interventions before issues become critical.
• Research and Development: Supporting material characterization and validation of new manufacturing processes.
• Structural Health Monitoring: Assessing integrity of critical infrastructure (e.g., bridges, pipelines) by identifying subsurface defects.

The standard’s comprehensive system characterization ensures reliable, repeatable, and accurate thermographic measurements crucial for safety, efficiency, and cost-effectiveness in NDT practices.

Related Standards

Organizations deploying ISO 18251-1:2017 for infrared thermographic NDT may refer to associated standards for terminology, testing methods, and system classification, such as:

• ISO 10878: Non-destructive testing - Infrared thermography - Vocabulary, which provides definitive terms used in IR thermography.
• ISO/TC 135 Series: Broader suite covering various methods and aspects of industrial non-destructive testing.
• IEC Electropedia and ISO Online Browsing Platform: For up-to-date terminology and cross-references in electrotechnical and general standards.

Integrating ISO 18251-1:2017 with related guidelines supports robust, consistent, and internationally recognized NDT procedures using infrared thermography technology.

Keywords: ISO 18251-1:2017, infrared thermography, non-destructive testing, IR imaging systems, system characteristics, NDT inspection, thermal imaging, industrial inspection standard.