vibration/dynamic stresses caused by in line inspection tool

[USER10]

Hello everyone
Can anyone provide guidance materials on estimating pipe dynamic stresses caused by ILI inspection pig tool . This is in relation to an exposed pipe installed on aerial bridge crossing,
Thanks

 

[1503-44]

I think you may be the first person to worry about that.

I would not expect dynamics to be a problem. They don't like to move fast, so you may be at a reduced flow rate when doing inspection anyway.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[USER10]

Pipes suspended on bridges or exposed pipes can be subjected to significant stresses as literature shows
This work by University of Calgary and TC Energy demonstrate that" Dynamic Stress Analysis of Exposed Pipes Subjected to a Moving In-Line Inspection Tool "
Another work " The study of the dynamic response of the natural gas pipeline aerial crossing during pigging process: A Review".
I thought to check if anyone here has dealt with this issue before

 

[1503-44]

I'm sure it can be "demonstrated". I'm just not sure that it's worth the effort. According to DOT statistics no aerial crossing has ever been recorded to have failed (in the USA) while a pipeline was in service and I don't see a problem with reducing operating pressure, if someone thinks there might be excess temporary risk while pigging. I myself have never heard of any issues with dynamic stresses created by pigging anywhere in the world. Perhaps you could post details of some you know about. Besudes that, the probable remedy is easy. It is not at all unusual to reduce op pressures when pigging anyway, especially when using intelligent pigs, as they tend to like steady slow velocities. I'd be much more worried when running cleaning pigs clearing liquid accumulations in high pressure two phase flow gathering pipelines subject to slugging when reducing pressure is not an option. That can be dangerous even without aerial crossings.





A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[LittleInch]

I think you've answered your own question....

Aerial crossings, especially long ones on flexible bridge type crossings are rare and not in common use, hence why I suspect TCE were studying it.

It you're looking at dry gas pipelines then you shouldn't have to worry about liquid and you could see some potential for setting up a rolling wave type event as the heavy pig transverse a flexible suspension bridge type crossing. However I find it difficult to believe it's a significant stress given wind loadings and the infrequency of such events.

But with those two documents (no links or references so I can't comment on them), I think you now know more than the rest of us do....

I've never dealt with anything like this and suspect only a handful of people in the world have. And they've written those two documents.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.