The pig analysis is performed on oil and gas pipelines to keep the assets free from debris and oil residue.
In order to clean the pipelines and scrape the debris, "scraper pigs" are sent through piping systems.
IDAC have been commissioned to analyse the interactions between a family of scraper pigs and the subsea check valves and wye pieces located in a number of oil and gas pipelines.
The work included specification and analysis of the upper-bound flow conditions, to calculate the highest impact loads on the pigs, check valves and wye pieces.
It also involved specification and analysis of lower-bound flow conditions, to evaluate the worst-case "piggability" scenarios such as pigs getting stalled or stuck when attempting to negotiate the check valves and wye pieces.
IDAC performed the analyses in ANSYS LS-DYNA.
3-D solid elements are used to model the flexible parts of the pig comprising the polyurethane noses and sealing discs. 3-D shell elements are used to model the rigid surfaces of the pipe, check valve, wye piece and pig.
Using the analyses BP investigated loading scenarios without having to construct additional expensive test facilities.
Also, IDAC performed additional work to understand the behavior of the sealing rings in case the pig was stuck and an estimation of the pressure required to invert the discs was identified.
