Ground Penetrating Radar & By Mike Kelty Western Technologies Inc.

Transcription

1 Ground Penetrating Radar & Thermorgraphy By Mike Kelty Western Technologies Inc.

2 Overview Types of Locating Methods/Equipment How GPR Works GPR Applications How Thermography Works Thermography Applications

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4 Radiography Structural field and shop full penetration welds Conduit, rebar, and post tension cable location in concrete up to 12 thick (IF access to both sides) Tank welds Voids in parent material Threaded fitting detection Crack and flaw detection Welder qualifications/certification coupons All ferrous and non-ferrous materials

5 Pachometer Location of ferrous materials (only) within non-ferrous parent material up to 6 deep Reinforcing steel in CMU block or concrete

6 Ferroscan Location of ferrous materials (only) within non-ferrous parent material up to 6 deep Reinforcing steel in CMU block or concrete Nail or screw locating in walls and floors Scans can be downloaded to PC for reporting

7 Ground Penetrating Radar Location of ferrous and non-ferrous materials within non-ferrous parent materials up to 18 deep (1.5 MHz antenna) in concrete or deeper in soils with good resolution Rebar, conduit, electric lines, large voids, and post tension cables in CMU block or concrete floors, walls and roofs Penetration depth of GPR in soil is dependent on the Megahertz of the transducer in the unit. The more penetration, the less the resolution.

8 Location Methods: Reinforcing Steel / Utilities Safety Radiogrpahy Pachometer GPR Ferroscan Metal Detector Thermography X X X X X Timely (area) X X X X X Accurate X X X Real Time Image X X X X X 3-D Soils X X X Non - Ferrous X X X Depth over 6" X X Extensive Training X X X X X

9 Basic Principles of GPR Radio transmitter and receiver connected to an antenna Radio signal reflection along time line Plot the echo for image interpretation

10 Basic GPR Components

11 Images Why a hyperbola? Ambiguous images

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14 Dielectric Table Material Dielectric Constant Pulse Velocities, m/ns Air Fresh water Sea water Sand (dry) Sand (saturated) Silt (saturated) Clay (saturated) Dry sandy coastal land

15 Dielectric Table Material Dielectric Constant Pulse Velocities, m/ns Fresh water ice Permafrost Granite (dry) Limestone (dry) Dolomite Quartz Coal Concrete Asphalt Sea ice

16 Utilities in Hotel and Casino Parking Area

17 Rebar and/or Grout in Failed Retaining Wall

18 What is Thermography? Measurement of temperature remotely and assignment of colors based on temperature Very effective to inspect Electrical equipment Electrical circuits Mechanical equipment Heating/cooling equipment Building envelope Water Intrusion Other

19 Thermal Imaging helps find/solve problems in process equipment Defective valves/traps Leaks in fluid and gas lines Tank levels Abnormal heat flow Over-heated pumps and compressors Over-heated drives caused: Worn parts Over-stressed parts misalignment

20 Thermal Imaging helps find/solve problems of moisture in buildings Water entering building structure through: leaks in building envelop failed and poorly installed plumbing Condensation caused by: improper construction poor building management air leakage All of which can cause health, comfort, safety and financial issues

21 Thermal Imaging helps find/solve problems of air leakage Poor construction Leaks around envelop penetrations like: Chimneys Plumbing vents HVAC lines Utility lines Leaks around window and doors Poorly installed siding and wraps Damaged and misfit heat ducts

22 Infrared Radiation Infrared radiation is electromagnetic radiation with wavelengths longer than visible light but shorter than microwaves

23 Phase Change Provides Moisture Detection Evaporation of the water into vapor draws heat from wall

24 1 st Law of Thermodynamics Radiation can be transmitted through a surface Our IR camera lens, for example Does not change the temperature of the surface! Radiation can be reflected off a surface Remember our glass window example? Does not change the temperature of the surface! Radiation can be absorbed and re-emitted Amount of energy absorbed = re-emitted This is what we measure with our IR camera! Reflected + Absorbed + Transmitted = 1 Known as the RAT law Can also say R+E+T=1 Absorbed Re-emitted Transmitted Reflected

25 Emissivity (ε ) Pronunciation: "Em`is*siv"i*ty Definition: scientific measurement of the ability for absorbed heat energy to radiate (leave) an object as compared to a black body at the same temperature a true black body radiates 100% of its absorbed energy (nothing is reflected or transmitted) so the ε = 1 A perfect reflector would have an ε = 0 Materials that are not black bodies only radiate a fraction of the radiation as a black body at the same temperature and wave length so the ε is <1

26 Example of a Specular Target Image of window shows high specular reflection Two hot spots are not in the window pane, they are reflections from hanging light fixtures To identify reflections from real hot or cold spots move camera; if spots move they are refections

27 Emissivity of Target Surfaces Emissivity Values (samples) Aluminum, polished 0.05 Platinum 0.08 Brick 0.85 Rubber 0.95 Bronze, polished 0.10 Snow 0.80 Bronze, porous 0.55 Steel, galvanized 0.28 Copper, oxidized 0.65 Steel, rolled 0.24 Copper, oxidized to black 0.88 Steel, rough 0.96 Skin 0.98 Tin 0.05 Nickel 0.05 Tungsten 0.05 Paint 0.94 Water 0.98 Paint, silver finish 0.31 Zinc, sheet 0.20

28 Thermography found loose connections Connections hotter than normal

29 IR, GPR, & RT Petrified Forest National Park 7.0 C

30 Missing grout Petrified Forest National Park 8.3 C

31 IR & GPR Petrified Forest National Park Bond beam Grout

32 IR Dusk Till Dawn Cabaret 24.5 C Expansion joint

33 GPR & Thermography Questions