Dear expert,
We have done pipe stress analysis for natural gas pigging line (aboveground piping with sleeper supports) around 2Km with 3D expansion loop considering design code ASME B31.3 and also the construction/hydro test of the line has been completed for 712.5 psig. Further to that the two times soft pigging was done successfully. Here the 3rd time normal pig is launched and after few minutes found that some portion of the line is fall down from the sleeper supports, line vibration was observed and most of the supports are damaged near the loop portion.

Kindly advice any additional force need to be considered for pigging operation. Also what may be the cause of failure?

Regards,
Venkat.A