DavidMack
Mechanical
- Mar 15, 2007
- 5
Imagine a situation where a pipeline is installed on top of a rock (never happens, right?). A sharp rock will make a sharp dent, meaning that the dent profile has a small radius of curvature. ASME B31.8R allows us to estimate the strain using the measured radius of curvature. Feature fails, case closed. BUT: what happens if that sharp rock only makes a very shallow dent, say 1/8 inch deep in a 36-inch pipe? The curvature of that dent is still sharp over a small area, so the equations still give us a high strain value, but common sense would tell us that such a shallow dent can't possibly be rejectable. I would like to know if anyone has encountered this problem and how they dealt with it.
In the figure below dent "C" is a very shallow dent with sharp curvature. Is it dangerous? Probably not.
We are seeing this problem more frequently with laser scanning of pipes that accurately detects areas of sharp curvature. We smooth the data enough so we don't pick up surface chatter, but we are still maybe over-sensitive to shallow dents with sharp curvature.
Thanks for your input,
DavidMack
In the figure below dent "C" is a very shallow dent with sharp curvature. Is it dangerous? Probably not.
We are seeing this problem more frequently with laser scanning of pipes that accurately detects areas of sharp curvature. We smooth the data enough so we don't pick up surface chatter, but we are still maybe over-sensitive to shallow dents with sharp curvature.
Thanks for your input,
DavidMack