Active Thermography

Advanced

Engineering

Mechanics

Analysis

What is Thermography?

Infra Red Thermography is a technique for

producing a visible image of invisible (to our eyes)

infra red radiation emitted by objects due to their

thermal conditions

Thermography

Objectives of Test

• To detect hot or cold area’s

• To determine absolute temperature

• To view Thermal profiles

• To detect temperature loss

• To detect material flaws, cracks

Thermography

Infra Red is part of the

Electromagnetic

Spectrum

• It travels in straight lines at

the speed of light

• The useful part is divided

between Short and Long

wavelengths

• Use of the correct

wavelength is essential

Test Equipment

• Laboratory Bench or Hand held

portable camera.

• Range…..-20°c to +1500°c

• Sensitivity…..0.1°c at 30°c

• Real time display

• Image Recording capability

Principles of Operation

• Object radiates infra red radiation

• Temperature differences are detected by IR

camera

• Differences are displayed visually

Advantages

• Non Contact

• Non Intrusive

• Can work at a distance

• Fast and Reliable

• Portable or in Laboratory

• Reliable Concluding Results

Limitations

• Non Intrinsically safe

• There must be a temperature difference for

certain surveys

• Operator experience is essential

• Filters may be needed for certain

applications

• Sensitivity and Resolution reduce with

distance and angle of view

Electrical Application

• Switch Gear

• Fuse boxes

• Cable runs

• Electrical connectors

• Insulation

• Transformers

Junction Box

22.7°C

43.7°C

25

30

35

40

SP01

Fan

18.7°C

37.4°C

20

25

30

35

AR01

Fuse Box

23.3°C

38.1°C

25

30

35

LI01

Electrical Connections

Used for the detection of;

• Corroded connections

• Slack / loose connectors

• Connectors at too high an

operating temperature

• Hot spots

Transformers

• Electrical connections

• Insulators

• Thermal profile

• Operating

temperature

• Liquid Level

Refractory Linings

• Torpedo ladles

• Boilers

• Furnaces

• Exhausts

• Ducting

• Kilns

Rotary Kiln - Access Door

77.8°C

129.3°C

80

90

100

110

120SP01

SP02

SP03

SP04

LI01

Kiln - Refractory Lining

22.5°C

48.7°C

25

30

35

40

45

SP01

SP02

SP03

22.6°C

58.5°C

30

40

50

SP01

SP02

SP03

LI01SP04

Torpedo Ladle

Steel Carrying Ladle

Building Surveys

Used to detect,

• Lack of insulation

• Cold air infiltration

Draughts

• Moisture traps

• Hot / warm air escaping

• Structural Integrity

• Heating / Cooling

Building Surveys

Moisture/Water Ingress

• Leaking Roof

• Bridged Cavity

• Leaking pipes

Refinery & Petro-Chem

• Vessel Surveys

• Blockages

• Defective lagging or

insulation

• Steam traps

• Erosion / Corrosion

Vessel Surveys

Flare Stacks

Process Plant

The above Thermograms show how

Thermography can be used as a very fast and

effective maintenance tool.

– The image on the right has a defective cylinder

Process Plant

Thermography may be

used for;

• Corrosion surveys

• Ensuring valve operation

• Leaks

• Blockages

Process Plant

• Hot spots

• Cold spots (Cryogenics)

• Damaged or missing

insulation

• Tank levels

Miscellaneous

• Detection of process or

manufacturing faults

• Detection of part flaws

• Can be used as a

quality control tool

Active Thermography

• An Energy Source is used to supply

thermal energy to the part

• The thermal response of a part in good

condition is used as a reference.

• Variations in the thermal response is

evaluated and interpreted

• Several types of energy sources can be

used

Active Thermography

Thermal Response

• The thermal response (Variation of

Temperature with respect to space

coordinates and time) is used to

determine the location of flaws and

cracks.

Conclusions

• Non Contact Necessary

• Rapid Scanning

• Data can be recorded in several

formats

• Images produced are comprehensive &

reliable

Thanks