Infra-red thermography is the science of using electric optical devices to detect heat from structures or equipment being inspected. Any object that has a temperature above absolute zero (-273.15 °C = 0 K) emits radiation in the infra-red region. Human eyes can only detect visible light (or visible radiation) between 380 and 700 nm, which is only a very small part of the electromagnetic spectrum. Although we cannot see it, the nerves in our skin can feel the infra-red radiation as heat and thermal imagers can correlate it to the surface temperature, once certain parameters – such as emissivity – are correctly set for that given material.
Thermal imaging can be used for building diagnostics or for mechanical, electrical and process inspections. Typical examples are:
Infra-red thermography is a non-invasive and non-destructive technique, which means that the article being examined is never altered during the inspection, with associated time and cost savings. The quick non-contact thermographic surveys are not disruptive (no downtime) and align with Health & Safety requirements when inspecting electrical and hot machinery in operation.
During building and industrial energy surveys a number of defects and inefficiencies which may not be visible to the naked eye can be easily identified by exploiting infra-red thermography. Equipment failures have clear and recognisable thermal signatures and temperature is an impeccable indicator of component failure before major faults occur. Most insurers apply a reduced insurance premium when infra-red thermographic surveys are regularly undertaken, which maximise the life expectancy of plant and equipment and minimise the risk of potential fire hazards.
The International Standard ISO 9712:2012 specifies the different requirements for the qualification and certification of personnel who perform non-destructive testing (NDT). The roles and responsibilities of personnel are generally as follows:
Infra-red thermographic reports should always be signed by competent professionals, i.e. level 2 or level 3 personnel, certified according to the ISO 9712:2012 standard.