full matrix capture (fmc) total focusing method or total
TRANSCRIPT
According to the EN 16018:2011 European standard:
Full Matrix Capture (FMC): full matrix capture specific data-acquisition process using ultrasonic array probes where each element in an array is successively used as the transmitter, while all elements are used as receivers for each transmitted pulse
Total Focusing Method or Total Electronic Focusing (TFM): electronic focusing which consists of adapting the receiving delay laws to focus at many points which form a grid, after a single pulse which generates a large and/or divergent ultrasonic beam
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
N emitters
N r
ecei
vers
Px
𝐸1
➢ Element n°1 fires
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
N emitters
N r
ecei
vers
Px
➢ Element n°1 fires
𝑅1 𝑅2 𝑅3 𝑅𝑁
➢ All the elements receives
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
N emitters
N r
ecei
vers
Px
➢ Element n°1 fires
➢ All the elements receives
𝐸2
➢ Element n°2 fires
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
N emitters
N r
ecei
vers
Px
➢ Element n°1 fires
➢ All the elements receive
➢ Element n°2 fires
𝑅1 𝑅2 𝑅3 𝑅𝑁
➢ All the elements receive
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
N emitters
N r
ecei
vers
Px
➢ Element n°1 fires
➢ All the elements receive
➢ Element n°2 fires
➢ All the elements receive
𝐸3
➢ Element n°3 fires
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
N emitters
N r
ecei
vers
Px
➢ Element n°1 fires
➢ All the elements receive
➢ Element n°2 fires
➢ All the elements receive
➢ Element n°3 fires
𝑅1 𝑅2 𝑅3 𝑅𝑁
➢ All the elements receive
➢ All the elements receive
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
N emitters
N r
ecei
vers
Px
➢ Element n°1 fires
➢ All the elements receive
➢ Element n°2 fires
➢ All the elements receive
➢ Element n°3 fires
➢ All the elements receive
➢ All the elements receive
𝐸N
➢ Last element fires
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
N emitters
N r
ecei
vers
Px
➢ Element n°1 fires
➢ All the elements receive
➢ Element n°2 fires
➢ All the elements receive
➢ Element n°3 fires
➢ All the elements receive
➢ All the elements receive
➢ Last element fires
𝑅1 𝑅2 𝑅3 𝑅𝑁
➢ All the elements receive
𝑠𝑛1 𝑡 … 𝑠𝑁1 𝑡…
1. Define a region of interest in the component
2. Time-of-flight calculation tij(P) for all couple (Ei, Rj)
Px
𝐸i 𝑅j
3. Amplitude extraction from each signal at time tij(P)
4. Sum of the N x N amplitudes
5. Perform the steps above for all pixels
N emitters
N r
ecei
vers
𝑡𝑖𝑗 = 𝑡𝐸𝑖𝑃 + 𝑡𝑃𝑅𝑗
Aij
Px
Electronic scanning• 8-element aperture• Focused along the defects in the middle• 57 shots
TFM• 64-element aperture• Focused everywhere• 64 shots
• Lateral resolution limited by the pitch; in this case 1 mm
• Focusing capability limited by the selected aperture
• Directive beam (along direction of propagation)
• Area of inspection limited to (N – A) * pitch
• Step size determined by the system (Gekko = 65536 pixels); in this case 0.15 mm
• Complete aperture for focusing
• Omni-directional beam
• Area of inspection > N * pitch
Sectorial scanning• 64-element aperture• Focused along the defects in the middle• Sectorial between -55° and 55° with 110 shots
• Optimal resolution at the point of focalisation
• Directive beam (along direction of propagation)
• Energy from N elements sent into the part
• Optimal resolution everywhere
• Omni-directional beam
• Only one element fired at a time
TFM• 64-element aperture• Focused everywhere• 64 shots
Hydrogen Induced Cracking (HIC) is caused by the blistering of a metal due to a high concentration of hydrogen. The blistering damage tends to form parallel to the surface
Once the ductility of the metal has reduced to a significant amount, the metal will form stepwise internal cracks connecting adjacent hydrogen blisters.
While the initial stage of HIC is not critical (individual cracking), it can become dangerous should HIC give rise to step-wise cracking that propagates into a weld or begins to go step-wise through the wall
The idea is thus to detect potential connexion between the various cracks before catastrophic failure
We compare standard electronic scanning to TFM
Escan FMC
By nature, the TFM from a FMC leads to a large beam spread so energy sent into directions capable of detecting the connexion between the crack
connexion
connexion
connexion
backwall backwall
HICHIC HIC
High temperature hydrogen attack is a form of damage commonly observed in steels exposed to highpressure hydrogen at elevated temperatures.
The damage occurs as hydrogen atoms diffuse into steels, react with carbon, form methane gasinternally in the material, which results in decarburization and fissuring (micro-cracking).
As the defects are quite small (micro) it is quite difficult to detect them with conventional UT method;an analysis of the backscattered energy is usually performed
TFM has been recently introduced by Oil & Gas companies and training centers as a mean to detectHTHA damage
To develop an new method the big difficulty is to have access to HTHA samples
Special test specimens were realized in similar conditions than the ones encountered on the field. They were thensectioned to expose HTHA cracks near the backwall
The specimen were metallographically ground and polished according to ASTM E3-01. Small cracks are visiblearound the grains
Equipment:
• We use our portable phased-array unit with embedded TFM: Gekko
• Manufactured specimen, 50-mm thick carbon steel
• Depending on the thickness we use 64-element linear arrays with frequencies ranging from 5 to 10 MHz
• We use off-the-shelf 2D scanners to scan the mockup
• For analysis, we do it onboard with the Gekko software, Capture, or off-line with our analysis software:Enlight
TFM area
PA probe
trajectory
The TFM area is positioned at the bottom of themockup to detect early stage HTHA
We use a 64L3-G2 probe
A 2D scan is performed over the mockup with a 1-mmstep along the scan axis and
Cumulated Tscan
Cumulated Tscan
Dscan
Dscan
Cscan
Cscan
backwall
In the Tscan, we can see smallindications initiating from thebackwall propagating 3 mm fromthe backwall
backwall
HTHA
In the Dscan, we can see that theHTHA indications propagate alongthe full length of the mockup
HTHA
The Cscan shows the cartography ofHTHA damage in the component
HTHA
The TFM allows full characterization(length, height) of the HTHAdamage inside the specimen
The sample is 100 mm thick
We use a 64L5-G3 probe
The TFM area encompasses the entire thickness. Thepixel size respect the ʎ/5 rule to avoid losing amplitudedata
We can detect HTHA going all the way up to 60 mm
For thicker materials the TFM can use in conjunctionwith lower frequency probe
HTHA
HTHA
Lavender is teaching HTHA detection and sizing courseusing TFM among several techniques
This course is founded on extensive work andexperience gained during industrial trials as part ofthe E2G HTHA JIP
Many data have been acquired using the TFMtechniques finding HTHA damage in the base material,the HAZ and weld
HTHA
Courtesy of Lavender
Samples with serious HTHA damage can leadto extended cracking
HTHA
Courtesy of Lavender
Lavender booth C04-41
Courtesy of BP
© BP Products North America© BP Products North America
© BP Products North America
TFM is being used by BP and its service providers to detect stage 1 HTHA
PAUT TFM and ATFM resolution is in the range of 0.3 mm (300 μm), a significant improvement over the techniques recommended in API RP 941.
TFM has been successfully introduced by Oil & Gas companies, services providers and training centersfor the detection of hydrogen damages
TFM offers high-resolution images that allow the detection and characterization of both HIC and HTHAdamages
The availability of portable equipment capable to perform real-time TFM offers a new tool to the NDToperator arsenal
Welcome to visit our booths D06-10 & C05-42