A Pig System is the practice of cleaning up moving liquid in a pipe using a plug called Pipe Inspection Gauge (PIG). This leaves no residual product in the pipe and secures against cross-contamination.

Nouryon site Stenungsund has the largest Pig System in Sweden. This system is divided into groups and Group 15 has breakdowns that lead to costly production stops. These stops can entail work from manually disassembling sections of the group to insert clearance pigs to blow out broken pieces of other pigs. It can also mean manual steaming where hardened raw material has collected. The reason all of this leads to production stops is that the area where maintenance is performed is considered dangerous during production and thus all reactors must stop during maintenance causing a lower OEE number.

The purpose is to find the root causes for corrective maintenance and to create a list of suggested improvements to mitigate production stops and thus optimising the production lines at the facility on-site.

During the work, the system is defined with schematics, components listed from archives, common problems listed from operators experience and this correlated to work orders that are provided by the internal documentation system at Nouryon on site.

The work orders are sorted by corrective maintenance and categorised from the text provided by the staff on the order. The categorisation of these work orders is where validity becomes a large factor in the study. The reason is that the text provided in these orders are written by individuals with different levels of detail and thus is an estimate of what the reason for the maintenance orders is. These orders are compiled and compared to what the reason for production stops are and prioritised.

The result of the study end with a list of improvements that covers all the different issues discovered. The problems and corresponding solutions are prioritised with an FMEA that is confirmed by stakeholders on site.

Further studies concerning lifetime calculation, alternative pigs and new sensors are suggested as all these reasons requires further investigation and testing to get a real answer concerning the pig system.