Pigs getting stuck in a pipeline is not a rare case during pipeline pre-commissioning operations. The real challenge is how to deal with it. The most common problems that usually happen in pipelines in South Pars Gas Field leading to pig stuck or stall conditions can be summarized as follows:
- Collision of vessel anchors with pipeline and sticking to it, causing damage and buckling to the pipeline;
- High length and low diameter (which leads to low cross-section area) of pipeline that makes the pipeline difficult for pigging, especially by using brush pigs which scrape the loose debris and produce a large amount of accumulated debris which blocks the pipeline;
- High erosion of pig disks in contact with pipe inner wall, since the contact surface of erosion is negligible compared to high length of the pipeline;
- Long interval between the time of laying and commissioning the pipeline which leads to production and accumulation of debris.