Challenge

To investigate the feasibility of uprating the 70 year old 108 km pipeline whilst, considering alternatives to the pre-commissioning hydro-test for demonstrating acceptable margins of safety and tolerable risk levels.  The client wanted to increase the throughput/capacity of the pipeline to meet future demand, by increasing the MAOP by 1.5 times the current MAOP.  The work reviewed the available data sources, identified the gaps and barriers to uprating and how they could be removed, and provided technical review and analysis to support the justification and direction for uprating.

The key challenges were:

• Pipeline Age (> 70 years);
• Material, manufacturing and construction quality;
• Extended operating life;
• Unknown historical operating regime;
• Availability of design and materials data;
• Providing a justified alternative to uprating without a hydro-test.

Services

Pipeline engineering consultancy services. The key activities were:

• Data gathering, review and gap analysis;
• Pipeline hydraulic analysis;
• Material testing specification;
• Probabilistic Fitness For Service (FFS) assessments, accounting for data uncertainty using Structural Reliability Analysis (SRA);
• Identification of uprating options;
• Uprating risk assessments and demonstration of ALARP.

Solution

• Identified barriers to uprating, providing recommendations for additional data gathering, inspection and analysis to remove them;
• Conducted probabilistic FFS assessments to determine the criticality of known defects and data uncertainty on the likelihood of failure at the uprated pressure.
• Performed risk assessments to demonstrate the change in risk when uprating was negligible, could be mitigated or was ALARP.

Result

The client was supported with technical knowledge, assessments and justifications that informed the uprating program, directed uprating activities, maintained the feasibility of uprating and permitted the pipeline to be uprated.