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Saipem aims for ‘safe life’ pipelines

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The challenges for subsea pipelines are becoming more complex as they operate in remote and harsh environments, and transport increasingly aggressive products across longer and/or deeper sealines
Lay vessels must align wider and heavier pipelines, and new concepts such as pipe-in-pipe (PIP), to specified routes in difficult conditions such as steep slopes, narrow corridors, rough seabeds and harsh metocean. Critical inline structures must meet stringent targets.

Such demands require high capacity equipment to handle, hold and protect pipelines during installation and monitor lay parameters in real time, according to Roberto Bruschi, vice president of advanced engineering services and innovation technology projects at leading international contractor Saipem SpA, Italy.

“Continuous investment in new and upgraded vessels is a key part of Saipem’s strategic response to offshore market needs,” he explains.

The Castorone dynamically positioned (DP) deepwater laying ship (pictured above) for operations in extreme environments, and the Saipem FDS 2 (DP) field development ship, illustrate this.

Castorone monitors lay progress and displays easy-to-read charts and data generated by integration of instrumentation and advanced calculation, such as real-time configuration of pipelines on the stinger and along the lay span.

“The stinger is really smart, not just a steel truss,” Bruschi said. The stinger tip can extend up to about 40 metres (m) aft of Castorone, and more than 90m below the sea in steep lay configuration, to guide pipelines carefully. This, and skilful pipe lay operators, maintains the working level of the pipe within allowance limitations, right up to its seabed touch down.

Stress on pipelines at points along the stinger and, after exit, along the lay span is continuously controlled.

“Monitoring the working level of each part of the equipment can be quite crucial during the most demanding operations and therefore for the laying season,” Bruschi stressed.

This enhances control of the pipe-laying operations and schedule, and allows speedy responses to unexpected events that cannot be excluded in open sea.

Increasingly powerful computing is one reason for Bruschi’s belief that future challenges can be met. “I started in the industry in 1980, and computers are now doing things 100 or even 1,000 times faster,” he said.

Applications include numerical simulation of most conditions and scenarios. Examples include the pipe and the lay vessel position near seabed targets under a specific setting for laying parameters, and for dynamic conditions under wave induced oscillations and slow drift counteracted by DP.

On mechanical design, Bruschi notes “a general consensus” around reliability-based design criteria, load-resistance factor design, and on continuous upgrading of design to reflect research and development.

However, for environmentally sensitive and remote locations, criteria for applying design to new applications should include assessment of consequences to health, property and environment across the widest range of factors and for the lifecycle of the pipeline, he argues.

It is not a case of just modelling the capacity of the actual material to perform in normal conditions, he said. Numerical modelling should anticipate and verify line pipe capacity to handle realistic demands under severe environmental events such as wave storms, geohazards or ice gouging.

“It is about safe life rather than fail safe,” Bruschi said. “The most important consideration for Saipem is safety. This applies to every element of planning, design and pipe-laying operations, and across all our people and levels of management. We have put a lot of effort into training and competency throughout the organisation.”

For pipelines to be safe, cost-effective and efficient 20 to 50 years on, the key is “robustness” throughout the lifecycle, Bruschi stresses.

“With pipelines in shallow to medium depths, across crowded and near-to-coast offshore basins, you have the possibility to intervene. You have a state of preparedness that can maybe accept a minor fail where it is not jeopardising the structural integrity and carrying capacity in the short term, without the need to intervene quickly,” he said.

If intervention is needed, then vessels and other resources can be lined up in good time. Experiences in the North and Mediterranean seas help to understand criticality.

“But what do you do if you have a winter season incident at Sakhalin or in the Barents Sea? Then you have to do something involving a huge spread of very specific working vessels in a very short time, and vessels are in short supply,” Bruschi challenged. “Would you not prefer to have a robust solution from the beginning?”

An increasingly integrated multi-disciplinary approach across surveying, design and installation is inevitable in his opinion, as is collaboration between industry, academia and others.

His view of DNV GL’s role in this ecosystem is that it has “a big ear” to what is happening worldwide through clients such as Saipem, and also through DNV GL’s Joint Industry Projects and now the Pipeline Committee and Innovation Forum.

Standardisation, such as the DNV-OS-F101 Offshore Standard for Submarine Pipeline Systems, can help to raise quality, reduce risk and lower cost. However, Bruschi also points out that responses to needs in deep waters off Brazil may be very different to those off West Africa, for example.

Saipem operates in the engineering, construction and drilling businesses, with a strong bias towards oil and gas-related activities in remote areas and deepwaters. Saipem is a leader in the provision of engineering, procurement, project management and construction services with distinctive capabilities in the design and execution of large-scale on- and offshore projects, and technological competences such as gas monetisation and heavy oil exploitation. Saipem operates in 62 countries worldwide with a workforce of more than 50,000 people of 129 nationalities.