Overview
ISO 18434-2:2019 - Condition monitoring and diagnostics of machine systems - Thermography - Part 2: Image interpretation and diagnostics provides practical guidance for interpreting infrared thermograms within machine condition monitoring and diagnostics programmes. The standard focuses on using thermal imaging (infrared thermography, IRT) to detect, assess and report thermal anomalies related to machine condition, performance and safety. It complements general thermography procedures by defining methods for severity assessment, safe data collection, image interpretation and reporting.
Key topics and requirements
The document addresses technical topics that are essential for reliable thermographic diagnostics:
- Severity assessment criteria: guidance on establishing baseline measurements and thresholds for anomalies identified by IRT.
- Equipment selection: recommendations for IR camera characteristics, lens choices (wide-angle, telephoto, macro), wavelength selection and use of infrared windows/sight glasses.
- Data collection requirements: what thermograms and reference photographs should contain, and how to manage capture speed, focus, standoff distance and repeatability.
- Error sources and accuracy: treatment of emissivity, environmental conditions, calibration, machine operating state and camera positioning.
- Image interpretation: principles for diagnosing thermodynamic causes (heat generation, heat transfer, applied heat, heat loss) and recognising abnormal heat distributions.
- Safety and reporting: procedures for safe thermography of machinery and standardized reporting requirements for condition monitoring records.
- Correlation with other technologies: using IRT alongside vibration analysis, electrical testing and other diagnostic tools to validate failure modes and determine severity.
Practical applications
ISO 18434-2:2019 is intended for use in:
- Predictive maintenance and reliability programmes - rapid scanning for hot spots and thermal trends.
- Machine diagnostics - confirming failure modes like friction, misalignment, lubrication issues or electrical faults that produce thermal signatures.
- Performance monitoring and quality control - monitoring processes with thermal properties (e.g., heat exchangers, extrusion, exothermic processes).
- Safety inspections - identifying abnormal heating that may indicate fire or electrical hazards.
Typical benefits include faster fault detection, non‑intrusive inspection, improved prioritization of maintenance work and better documentation for decision-making.
Who should use this standard
- Condition monitoring engineers and reliability professionals
- Industrial thermographers and predictive maintenance technicians
- Maintenance managers and plant engineers
- Inspection and safety teams using infrared cameras for diagnostics
Related standards
ISO 18434-1 (Thermography - Part 1: General procedures) and other condition monitoring standards such as ISO 13372, ISO 13373-1 and ISO 13379-1 are closely related and referenced for terminology and broader monitoring procedures.