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Technical Discussions
MM Damani
MM Damani
00:00 Feb-12-2003
Hidden Crack in Graphite Electrodes

USE OF ACOUSTIC RESONANCE FOR DETECTING HIDDEN CRACKS IN GRAPHITE ELECTRODES”


Q.1 Whether Acoustic Resonance method uses mechanical waves having sinusoidal oscillations?

Q.2 Whether the Instrument is capable to detect cracks, extrusion defects, cavities, porosity etc. in Carbon / Graphite Electrodes?

Q.3 If yes what the level of Precision and repeatability of Test?

Q.4 Whether it is possible to check carbon / Graphite Cylindrical Rods of diameter ranging between 250 mm to 700 mm and length between 1800 mm to 3000 mm?

Q.5 Is it possible to carryout Acoustic resonance test on Pitch Impregnated Carbon Rods for ascertaining pitch pickup level after impregnation?



    
 
 Reply 
 
Godfrey Hands
Consultant,
PRI Nadcap, United Kingdom, Joined Nov 1998, 301

Godfrey Hands

Consultant,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
301
01:49 Feb-14-2003
Re: Hidden Crack in Graphite Electrodes
Hi There,

My company uses the Quasar Resonant Inspection equipment for inspecting components. This uses a sinusoidal wave to excite the parts mechanically.

We are normally able to detect Cracks, Extrusion defects, Cavities, Significant amounts of Porosity and many other conditions in Metal and Ceramic components, as well as Ferrite. To my knowledge, we have never tested Graphite electrodes, but as the technology is quite new, it will only be a matter of time before it is tried on Graphite.

We normally measure resonances with a precision of "a few Hertz" for optimising testing speed, but the system has a resolution capability of 1 Hz. Our measurement errors (repeatability) are typically 0.01% or smaller at higher frequencies, and perhaps 0.05% at lower frequencies.

We normally test components in the weight range 20 Grams to 20 Kilograms, but are currently experimenting with components around 50 to 70 Kg. I see no reason why the technology shouldn't test your electrodes.

I think that it is unlikely that we will be able to determine the pitch pickup level of pitch impregnated electrodes, but cannot rule this possibility out.

Please provide your location, and I can arrange that your nearest Quasar Application Engineer or Sales Person contacts you to make some trials on some of your electrodes.

Regards,

Godfrey Hands

-------------------------------------
: USE OF ACOUSTIC RESONANCE FOR DETECTING HIDDEN CRACKS IN GRAPHITE ELECTRODES”
.
:
: Q.1 Whether Acoustic Resonance method uses mechanical waves having sinusoidal oscillations?
.
: Q.2 Whether the Instrument is capable to detect cracks, extrusion defects, cavities, porosity etc. in Carbon / Graphite Electrodes?
.
: Q.3 If yes what the level of Precision and repeatability of Test?
.
: Q.4 Whether it is possible to check carbon / Graphite Cylindrical Rods of diameter ranging between 250 mm to 700 mm and length between 1800 mm to 3000 mm?
.
: Q.5 Is it possible to carryout Acoustic resonance test on Pitch Impregnated Carbon Rods for ascertaining pitch pickup level after impregnation?
.



    
 
 Reply 
 
Lalit Chandra
Lalit Chandra
08:03 Mar-27-2015
Re: Hidden Crack in Graphite Electrodes
In Reply to Godfrey Hands at 01:49 Feb-14-2003 .

Dear Sir,

I am working in a graphite manufacturing plant. very much interested to know the results of any test/experiments with graphite cylindrical rods.

if your company did any experiment to detect cracks inside these electrode rods please let us know.

lalit

    
 
 Reply 
 
Godfrey Hands
Consultant,
PRI Nadcap, United Kingdom, Joined Nov 1998, 301

Godfrey Hands

Consultant,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
301
12:29 Mar-27-2015
Re: Hidden Crack in Graphite Electrodes
In Reply to Lalit Chandra at 08:03 Mar-27-2015 .

Hi,
I no longer work directly with this company, but I can get more details sent to you.
Please provide me with contact details to my email address.
Please use the email option in NDT Net.

Regards,

Godfrey Hands

    
 
 Reply 
 
Godfrey hands
Consultant,
PRI Nadcap, United Kingdom, Joined Nov 1998, 301

Godfrey hands

Consultant,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
301
16:31 Jan-19-2017
Re: Hidden Crack in Graphite Electrodes
In Reply to Godfrey Hands at 12:29 Mar-27-2015 .

Hi,
I have recently had another enquiry about testing Graphite Electrodes with this technology.

Back in 2003 when this idea was first considered, this technology was very new, and nobody knew exactly what potential there was for inspecting Graphite electrodes, although it had been considered a possibility.
14 years later, and we now know a lot more about what can be done and what is doubtful, and inspection of large Graphite Electrodes now appears to fall into the "Doubtful" category, although some limited success has been reported for inspecting Graphite components of up to about 2Kg for major defects.

The technology is however still an excellent tool for mass-production of smaller metallic or fired ceramic components.

Godfrey

    
 
 Reply 
 
Krishna Bhuta
Director,
Own, India, Joined Jun 2014, 6

Krishna Bhuta

Director,
Own,
India,
Joined Jun 2014
6
08:34 Jan-23-2017
Re: Hidden Crack in Graphite Electrodes
In Reply to Godfrey hands at 16:31 Jan-19-2017 .

Hi, I had worked on this project some tiem back, its possible to carry out UT inspection fro mass production too if require.

    
 
 Reply 
 
Simon Amallraja
Consultant, Advanced NDT Methods
Anu Consultants, India, Joined Aug 2013, 38

Simon Amallraja

Consultant, Advanced NDT Methods
Anu Consultants,
India,
Joined Aug 2013
38
15:06 Jan-23-2017
Re: Hidden Crack in Graphite Electrodes
In Reply to MM Damani at 00:00 Feb-12-2003 (Opening).

You can use 410D model from Sonatest UK. Since you wanted to check Porosity etc., you can use Air Coupled System for this application as it can give a C Scan image and porosity, other mentioned defects.

If you are in India, you can contact me for further details. www.anuconsultants.net

    
 
 Reply 
 
Dustin
Dustin
12:42 Aug-11-2017
Re: Hidden Crack in Graphite Electrodes
In Reply to MM Damani at 00:00 Feb-12-2003 (Opening).

I had purchased Graphite Electrode RP 350 mm * 1800 MM with 4 TPI nipple plus 3% wherein the there is a serious quality problem. During operation of the electrodes in electric arc furnace, several times slipage happened. Can you kindly know me the technical deficiency in graphite electrodes due to which such slipage is happening.

    
 
 Reply 
 

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