Non-destructive strength measurement
Non-destructive strength measurement
(OP)
I have a small population of completed welds whose strength is suspect. We're not prepared to rework everything, and we have too many to perform destructive strength testing. I need a non-destructive way of estimating the strength of the joint.
In words, the joint is supposed to be a complete joint penetration groove weld all-around, 3mm size, used to splice two ASTM A500 4" square tubes (3mm thickness) together end-to-end.
Can you think of a method I can use for this non-destructive examination need? This isn't a regulatory requirement. We are thinking that we will take another look at our applied loads and see if "what we have" is good enough.
Thanks!
Elliot
In words, the joint is supposed to be a complete joint penetration groove weld all-around, 3mm size, used to splice two ASTM A500 4" square tubes (3mm thickness) together end-to-end.
Can you think of a method I can use for this non-destructive examination need? This isn't a regulatory requirement. We are thinking that we will take another look at our applied loads and see if "what we have" is good enough.
Thanks!
Elliot





RE: Non-destructive strength measurement
RE: Non-destructive strength measurement
We have performed radiography with the disappointing result that the welds fail the standard, but to an unknown degree. If the X-ray image could tell thickness with any certainty, we would be doing fine!
I found a method of UT called "crack tip diffraction" (http://w
RE: Non-destructive strength measurement
If the joint is supposed to be CJP and it's not then it's fatigue performance will be compromised.
Just bite the bullet and rework things now. It will be faster and cheaper for you in the long run.
RE: Non-destructive strength measurement
RE: Non-destructive strength measurement
RE: Non-destructive strength measurement
If the defect was lack-of-penetration at the root of a 1/2" 12mm thick tube, and there were more than a couple of tubes, UT testing and engineering recalculation might be worthwhils. The UT tech has to be able to perform Crack Sizing, because reliable depth measurements are critical.
RE: Non-destructive strength measurement
RE: Non-destructive strength measurement
http://w
http://ww
RE: Non-destructive strength measurement
Again, piling on with MJ, strength is not the only consideration. Some weld flaws, particularly root discontinuities, can be detrimental for long term crack potential, even in mildly dynamic situations such as moderate temperature fluctuations. As MJ noted, if the conditions are susceptible to fatigue or vibration, then why take on the liability and risk of known defects in the weld?
Failing tests or observations have to be resolved or your liability can increase exponentially.
Why did it get so far with bad procedures? You might want to re-visit your QA/QC program.