16" BISEP with Integrated Bypass on Sloped Pipelines, France

A major gas transport operator in South Europe, needed to carry out planned maintenance on a 16" natural gas transmission pipeline without interrupting customer supply. STATS patented BISEP line stopping technology was utilised to deliver a verified double block and bleed isolation on a steeply inclined pipeline, where conventional line stopping could not provide the same leak-tight, high integrity barrier.

To facilitate planned maintenance, two 16” BISEPs were deployed approximately 500m apart with an integrated bypass to provide a midline isolation while maintaining continuous flow.

The worksite was located in mountainous, difficult-to-access terrain. Mobilising specialist equipment required careful logistics, while the pipeline inclination created a more fundamental isolation challenge.

STATS selected BISEP because the pipeline’s steep inclination limited the suitability of traditional line stopping. Conventional systems typically rely on a passive single seal, which cannot provide an independently verified isolation in this application and may require additional mitigation measures, including gas bags and secondary interventions, to achieve an acceptable safety barrier and leak-rate performance.

The STATS BISEP provided a fundamentally different approach. Two independently activated seals created a proven Double Block and Bleed (DBB) isolation barrier, allowing the integrity of each seal to be monitored and verified independently throughout the maintenance period. This enabled personnel to work safely behind the leak-tight isolation without the need for gas bags or supplementary bypass installations.

The integrated bypass system maintained continuous gas flow throughout the operation, eliminating customer supply disruption and significantly reducing operational complexity, risk, environmental impact and overall project duration.

A key factor in the project's success was the support provided by LINEOP, whose local project assistance and translation services helped ensure clear communication between all stakeholders throughout planning and execution. The collaboration demonstrated the value of combining STATS' specialist isolation technology with experienced local support and established a strong foundation for future projects with the client.

A temporary logistics base supported equipment handling and transportation. Drawing on its local knowledge and specialist transport equipment, the client's contractor safely moved the isolation equipment and project materials across the difficult terrain to the worksite.

With the equipment safely mobilised, STATS deployed the BISEP hydraulically activating two energised seals with a monitored bleed between them. Each barrier was independently tested and continuously monitored, confirming the integrity of the isolation throughout the maintenance period despite the pipeline’s steep inclination.

The combined technical and logistical approach delivered a safe, verified isolation with no interruption to customer gas supply.