DBP manages all of its asset’s integrity using proven and tested programs that are part of its Asset Management Plan. The integrity is managed by ensuring the coating used on its projects are tested and approved.
The DBNGP had invested extensively in the use of Fusion Bonded Epoxy coating for all its assets installed in the late 1980s as well more recently the use of 3 layer Trilaminate coating. Fusion bonded epoxy coating remains the preferred choice for coating of below ground pipelines. Once commissioned and operational, the in-service performance of coating is monitored and areas of weakness are investigated, repaired with data recorded for future reference.
The pipelines are also equipped with facilities to enable the wall thickness of the pipeline to be measured using intelligent pigs. A large majority of DBP assets are piggable and undergo intelligent pigging programs on a scheduled 5 and 10 year basis.
The planning for and implementation of the intelligent pigging program involves close consultation with all shippers to ensure the conditioning of the pipeline to enable the safe travels of intelligent pigs does not compromise supply integrity to customers. The intelligent pig is launched at specially provided facilities located at the compressor stations and the flow of gas is controlled to ensure the speed of travel is kept to within the relevant range that enables the tool to measure the wall thickness of the pipeline. A successful pigging run takes around 8 hours to travel from one compressor station to the next.
The data collected by the intelligent pigging tool is protected and processed by the intelligent pigging vendor with DBP integrity management engineers. The data is assessed against the design criteria of the assets and the integrity confirmed. Areas where the pipeline does not meet the design criteria are investigated and repaired.