Crack detection 1

[vtmike]

Hi,

We deal with tubes which are about 7" dia and 10' tall. Can anyone suggest a non destructive testing method of finding the cracks in these tubes and measuring them. Which would be the fastest way to detect cracks?

Thanks,
Mike

 

[rb1957]

internal cracks ?

thru-thickness cracks ?

material ?

length ?

 

[desertfox]

Hi There

X ray, magnetic particle

desertfox

 

[Twoballcane]

Using spectrometer and helium...

Tobalcane
"If you avoid failure, you also avoid success."

 

[hacksaw]

the technology depends on whether this is a quality control issue or on-going in-situ testing

 

[diskullman]

sonic testing?

http://www.buzzmac.com/

Russell Giuliano

 

[rebelbrill5]

What do you need to know about the crack(s)? Are orientation, size, shape, location relative to a surface, or other features important? Do you have basis for accepting/rejecting product (acceptance criteria) based on the results of you inspection?

If the cracks of interest penetrate a surface, a surface inspection technique may be used to detect them. If they do not penetrate a surface, then a volumetric technique must be used. In either case, a volumetric technique can provide more information about the cracks.

 

[vtmike]

To rb1957:
detection of through thickness & surface cracks
material: steel
length: 7 feet
Diameter: 7" to 8"
Thickness: 0.425"

 

[rb1957]

mag particle would be effective for cracks breaking the outer surface. you'd need something like eddy current or ultra sonics to detect other cracks. personally, i don't like X-rays (only good for showing you had a crack, after the thing has broken in 2). but this should be readily available, try google.

 

[insult2injury]

Many tubing suppliers have the capability of performing on-line UT testing for a modest price/foot.

I2I

 

[metengr]

vtmike;
What is the matter with not answering the questions posed above? You do not provide any additional information;

NDT for crack detection, hm....mm, lets see

UT -shear and L wave
UT - TOFD, linear and phased array
Liquid PT
Wet fluorescent MT
Fluorescent PT
Acoustic emission
Radiography
Eddy Current
Remote field Eddy Current

Get the drift?

 

[mchljackson2007]

Hello every body,

Can anyone know that how to use the ANSYS software to estimate the initial cracks of thermal cyclic loading? we due with the material H13 of rectangle block which is 100 mm and 45mm. I wish can hear your support soon.

 

[israelkk]

mchljackson2007

You should start a new post instead of jumping into an existing post with different issue.

To your question the initial crack size is the result of the maximum crack that the quality tests conducted on your part can not detect.

For example if you weld two parts and use an X-ray to check for cracks. The crack estimation size will be the largest size that can not be detected by the X-ray method.

n your case you should check the history of the part including all processes and tests conducted on the part and the raw material and select the largest crack that could be in the part that no test that was done on the part/raw material could find.

 

[vtmike]

Rebelbrill5 and metengr,

Sorry for the late reply...We test the tubes with shock loads and then check if the tube has survived the shock by looking for cracks and splits that are too deep and wide (currently this is done by visually inspecting them)......so basically the crack length and depth are important parameters
There are a lot of crack detection systems out there but am looking for one where we can scan the part and get measurements on the length and depth quickly.....X ray & mag particle seems to be a good option but I dont knw which would be the fastest method.

Thanks,
Mike

 

[hogan666]

if you have significant wall thickness i would suggest using UT shear wave

 

[vtmike]

wall thickness is 0.4" to 0.8"

 

[rb1957]

i'd avoid x-ray myself.

how many pieces per day are you inspecting ?

how big a crack do you want to detect ? carefull how you answer this, as it'll have a big impact on techinque, cost, time.

is there a particular zone that you're interested in (maybe a weld) ?

what are you doing to the material to make you think you'll develop cracks under (compression) impact loads ?

 

[vtmike]

how many pieces per day are you inspecting ?
between 2 to 4 peices per day
material: steel
length: 7 feet
Diameter: 7" to 8"
Thickness: 0.425"

how big a crack do you want to detect ?
The crack sizes vary with the loadings....the sizes range between,
Length: 0.2" to 2"
Depth: Not sure about the depth as we have been inspecting them visually until now.

is there a particular zone that you're interested in (maybe a weld) ?
There are no welds on the surface.....It is just a hollow cylinder, so want to scan the outer surface of the cylinder.

what are you doing to the material to make you think you'll develop cracks under (compression) impact loads?
The cylinder is impacted by a bullet from the inside which blows holes into the cylinder and we want to check if the rest of the body survives this impact.

My plan is to check the part visualy for any indication of surface cracks and then use a NDT method for measuring any cracks that are spotted. There are usually 3 to 4 cracks, so we don't really need to scan the whole cylinder just to measure 3 or 4 cracks?

 

[RossABQ]

I agree with using shear-wave UT.

I'd ask about the bullet but I suspect ths is classified?

 

[vtmike]

Yes unfortunately i cannot give out more information....but UT shear wave looks like a good option to me too.
Do you know how long does it take to measure a crack using the shear-wave UT method? and before i can get a quote approximately how expensive do you think it might be?

Thanks for the help,
Mike