Thermography

Thermography refers to the method of using a high sensitivity infrared (IR) camera to scan a variety of in-service assets and assess their temperature distribution. Skilled ALS certified technicians can interpret these scanned temperature distributions, called thermograms, and extract information about a component's condition and diagnose underlying root causes.

ALS certified thermographers utilise standards such as ISO 18434 and ASTM E1934, that provide specific guidance on the interpretation of infrared thermograms as part of a programme for condition monitoring and diagnostics of machine systems. The condition of assets is then established through the framework of ISO17359 by monitoring temperature as a symptom of the identified equipment failure modes.

Thermography is a valued diagnostic tool that is critical to understanding condition across a broad range of assets.

Some typical applications include the identification of:

• Scale and build-up in tanks and pipes.
• Erosion inside internally lined or internally coated pipelines.
• Pipeline blockages.
• Electrical faults and high resistance connections in switchboards, transformers, cables and other electrical components.
• Loss of insulation materials (e.g. Refractory) in high or low temperature process equipment.
• Damage to rotating equipment, particularly from rubs, lubrication, electrical and cooling issues.
• Pipeline leaks of hot and cold fluids, including gases (hydrocarbon) not visible to the naked eye.
• Cooling circuit blockages and/or heat exchanger inefficiencies.
• Conveyor idler defects.

Examples of Thermography Application 

Electrical Connections

High resistance connections due to lose connections, component damage or corrosion can easily be identified utilising thermography on in-service and loaded switchboards.

Tanks

Thermography is widely adopted in tank assessment. The technique has varied capabilities from assessing sludge levels at the bottom of a tank through to assessing scale build up on the tank wall. Thermography is able to visualise the heat distribution and is commonly used to guide cleaning and maintenance regimes. 

Pressure Relief Lines

ALS conducts routine thermographic surveys on pressure relief lines which are subject to scale and mud build up as part of the refining process. The heat signature of the pipelines reveals areas which are free from any restrictions, whilst also pinpointing areas requiring descaling or cleaning.

Corrosion Under Insulation (CUI)

Thermography can be used to conduct online surveys for areas prone to suffering Corrosion Under Insulation (CUI). Thermography identifies areas of relatively wet insulation under aluminium or galvanised steel cladding. Moisture from water ingress forms an electrolyte which is an essential requirement for CUI. The presence of moisture is detected by thermography due to differences between the thermal conductivity and specific heat capacity of water compared to that of dry insulation material. Moist areas in an insulation system can then be further investigated using specialist CUI NDT tools such as on-line pulsed eddy current.  Alternatively, these areas can be identified for local insulation removal to quantify the extent of metal loss using ultrasonic thickness techniques during a shut-down/ outage.

Advantages of Thermography

Thermography is an online, non-destructive, non-contact monitoring and diagnostic technique that provides valuable insights into an asset’s condition. With this insight, the necessary maintenance and monitoring can be scheduled, and optimal asset output can be maintained.

Thermography has broad applications which makes it a viable solution for many assets across a range of equipment types.

ALS also provides training to clients in the techniques of Thermography. Click here for further information about our Thermography Level 1 course or contact us directly.