Deleted

By ssbn727 (*****)

Date 04-11-2015 03:12 Edited 04-11-2015 03:24

You need to include many more variables in order to get an educated answer to your query... And please include all specific details and no assumptions... You may also want to post this in an engineering forum such as this one:

http://www.eng-tips.com/

Here's another link which may be very helpful for you:

http://www.eng-tips.com/threadminder.cfm?pid=1529

Finally, here's an interesting quote for you:

"It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)"

By Inspector Date 05-03-2015 12:07 Edited 05-09-2015 10:18

By js55

Date 05-04-2015 15:08

Inspector,
You are overthinking it.
First of all there is no Code that I know of that allows cracks of any kind. So any relation to fracture mechanics is moot.
Second, to say that something "is not wanted" is irrelevant. Welds are full of discontinuities not imposed by welding defects per se.(inclusions, grain boundaries, fusion lines, external reinforcement, etc). The threshold is generally considered to be low enough based upon empirical data.
I'm sure one could justify greater leniency based upon some material characteristics but why?
Sometimes it is best to simplify.
Also, intensification of stress does not necessarily cause a part to fail.

By js55

Date 05-05-2015 12:53

Perhaps I need to correct what I have since determined as a misstatement. Clearly fracture mechanics is related to crack initiation mechanisms pertaining to defects, the most severe of which is of course planar. But overall the argument is the same. Not all that is codified is based upon calculation and theory. Most of it is empirical.

By welderbrent (*****)

Date 05-04-2015 15:45

The engineers take all the data on fracture mechanics and material loading and strengths as well as the discontinuities from the applicable code into account with design in the first place.

All we have to do is make sure the parts meet the specified code with any additional conditions placed in the Job Specifications.

He Is In Control, Have a Great Day, Brent