Dewatering
Once a hydrotest has been completed, the same pig as was used to fill the line will be run back to the launch site utilizing compressed air. Pipeline dewatering can be one of the most dangerous procedures in the pre-commissioning process. This is due to the fact that air is compressible and water is not; large air pockets develop in front of the dewatering pig creating violent releases of air/water at the terminus. APS Technicians monitor the pig as it dewaters so that valves and piping at the release point maintain a constant backflow pressure to minimize danger to both personnel and equipment. Once pipeline dewatering is complete the drying process can commence.