Challenge

An offshore operator has developed a field as a tieback. The pipeline system consists of 8”/12” Pipe-in-Pipe (PIP) production flowline between the well and the Subsea Isolation Valve (SSIV), alongside a dynamic production riser between the SSIV and the IRHS. 

Services

The scope of the annual TIA of an 8″/12″ PIP pipeline is to:

• Review of start-up operations data (pressure/temperature) against Safe Operating Limits (SOLs);
• Review management of Integrity-Critical Elements (ICEs), such as 8” Emergency Shut Down Valves (ESDVs), including leak tests and closure tests of ESDV;
• Review of pre-commissioning (pressure test data), riser system survey reports and inspection and maintenance activities for pipeline element topsides and subsea structures, including SSIV manifold pipework, umbilical, spools etc. from last flange on each well Christmas tree.
• Review studies, Emergency Response (ER) exercises, incident investigation reports and all other pipeline integrity activities.

Solution

The pipeline was in service for under a year when this integrity assessment was undertaken. Following full review and analysis of reported service and operations data, the line has been found suitable for continued operation.

Result

The project lacked full inspection and integrity data from topsides, however considering the inspection schedule and risk assessments from Penspen’s RBI at commissioning, the line was deemed to be in satisfactory condition and a statement of integrity issued.