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Thermax Infrared Firetube Inspection

Infrared Thermography
for Proactive Maintenance

Use infrared thermal vision to survey the condition of firetubes in refinery preheat ovens and steam boiler tubes.

Visually detect internal fouling in heat exchanger firetubes

Visually identify external, abnormal conditions on firetubes

Visually detect abnormal conditions in steam boiler tubes

Thermax Infrared Firetube Inspection uses a thermal imaging camera to survey the condition of firetubes in refinery preheat ovens and steam boiler tubes.

This work is highly technical, and requires a proven inspection method. Variables affecting the inspection are flame interference, internal reflections, geometry of the pre-heat oven, emissivity of the firetube, ambient temperatures and limited access from port holes.

A short wave infrared camera, also known as a thermal imaging camera, operates in the 3um to 6um wavelength. Fitted with flame filters, this infrared camera is capable of measuring high temperatures, which are used to capture thermal images of firetubes.

With image processing software and technical experience, we analyse the images and extract the temperature at any point. By applying ‘trending’ of the data, we can identify the internal and external conditions of your heat exchanger firetubes.


Thermax provides me with my annual furnaces inspection. Ian and his team are reliable, thorough, knowledgeable and a pleasure to work with

Thumi G

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Fire tube with internal problem. Reduced heat transfer. Tube at higher temp. Tube bowed.

Fire tubes with holding brackets in good order plus temp of tubes.

Refinery preheater oven - Fire tube condition inspection

Detect internal fouling

Fouling is a buildup of material on the internal surface of firetubes. Tubes preheat crude oil destined for the distillation unit. Fouling can be caused by crystallization, sedimentation and coking. Tubes with internal restrictions will:

  • Run at a higher pressure causing chemical changes
  • Flow rates at restrictions will be higher causing erosion inside the tube, and wall thinning
  • Increased pressure and wall thinning can lead to tube ruptures
  • Heat transfer is reduced costing more energy to operate

Fouling increases the costs of operating the preheat oven. Thermax-IR Firetube Inspection helps you to detect internal fouling.

Identify external firetube conditions

A. Flame impingement that cause damage from:

  • Erosion as the flame “rubs” the tube surface and burns it, depositing residue
  • Corrosion from the chemistry inside the flame and the residue left on the tube
  • Scaling, that is a result of corrosion of the tube
  • Tube bulging leading to tube rupture

B. Defective components:

  • Loose, hanging tubes from holding bracket failure
  • Broken thermocouple mountings

Flame impingement is caused by poor burner management.

This increases energy consumption and costs. Thermax-IR helps you to detect flame impingement, and defective components.

Flame impingement and defective firetubes increase energy consumption and costs.

Assess steam boiler tubes

In boiler tubes, energy is transferred from hot gas to water to produce pressurised steam.

  • Blocked, cracked or damaged tubes lead to reduced heat transfer, raising the cost of operating the boiler
  • Steam leakage from a pinhole in a firetube may go undetected, but escaping or cooling steam is lost energy and therefore lost money
  • Escaping steam in a hydrocarbon vessel is extremely explosive, and creates the risk of damage to surrounding equipment, plant materials and it lowers staff safety.

Use Thermax-IR Firetube Inspection to assess the internal and external condition of your firetubes.


Conform to SHEQ requirements (Safety, Health, Environment, Quality)

Reduce risk of explosion, fire and consequential damage

Avoid unexpected shutdowns

Extend the life of capital equipment

Save money

Reduce energy usage

Improve operations

Implement Proactive Maintenance

And more...

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You may also need

Another way to improve efficiency of the preheat unit is to identify refractory failures. Thermax-IR offers this service using a detailed thermographic inspection.

Read more


A client at an Oil Refinery shared this story with us: 

The production department noticed that the product flow through one of their units was declining. To maintain the target throughput, they increased the inlet pressure of the feedstock. No investigation was made to determine why the flow was reduced.

The design parameters of the aging equipment were ignored; an old tube cannot withstand the added pressure for long, and so it burst. Hot crude oil was injected into a blazing furnace, causing costly, consequential damage.

Production was forced to shut down the unit, and a rebuild was planned and commissioned.

The shut provided the opportunity to rebuild the refractory, although, it was not scheduled for a rebuild for another 12 months. Materials were ordered, imported, and installed, and the unit stood standing for 8 weeks.

The rebuild cost of this avoidable problem was millions of Rands. Add to this the cost of lost production due to downtime, and the costs incurred to avoid breach of contracts with buyers of the refined fuel, and the financial cost to the company was enormous.

Proactive firetube inspections would have prevented this problem, and given less stress to all the people involved (except the suppliers selling new materials for the rebuild!).

An investigation shows that the firetubes causing the problem were affected by coking, a condition that is identified by Thermax-IR Firetube Inspection.

Sometimes Maintenance needs a little help convincing Production to schedule a shutdown for maintenance. A thermal inspection gives you the evidence you need to back up your case. Otherwise just tell them this story.

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