UT inspection - "Leg" definition

[atomicman]

I'm not that familiar with UT testing to D1.1 and am trying to educate myself on it. What does "leg" mean? Reference specification for a project says "testing in leg 4 will not be accepted"

My thought is that it has to do with the reflection of the wave and the testing of welds where you don't have close access to the weld.

 

[weldtek]

Look in the definition section of D1.1 under 'Leg' for clarification.

 

[NDTLevel3]

The UT sound wave enters the part at an angle, 45 degrees for example, and travels from the OD surface to the ID surface. The path it takes is called the first "leg". Following the law of reflection, the sound bounces off of the bottom at a 45 degree angle headed back toward the OD. This is the second leg. It will continue to bounce in this manner through the third leg and so on. The problem is that the sound begins to spread out and may be mode converting out beyond the third leg (with a 45, higher angles may mode convert quicker) causing signals that my be misinterpreted. This is just one of the reasons for not inspecting in the fourth leg.

William E. Blum
Manager
NDT Consulting Group Inc.

http://www.ndt-cgi.com

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