flexible pipe layers

Flexible Risers, Flowlines & Umbilicals

Independent engineering assurance and expertise at all stages of the flexible pipe and umbilical lifecycle

Flexible pipes are complex structures that require specialist engineering and a multi-disciplinary team to ensure an optimised design, careful manufacturing, reliable installation, operation, and long-term integrity. From the conceptual stage to life extension projects, we work with all types of operators, EPCI contractors, and directly with OEM. Our collaborative approach has allowed us to gain in-depth knowledge and expertise that adds value to every flexible pipe and umbilical project. We have experience in all major offshore exploration regions, in shallow to ultradeep water, and with old and new pipe designs. We are comfortable working with any standard configuration or developing new/novel configurations for both O&G and renewable energy applications.

Design & Analysis

flexible riser layout

Flexible pipe expertise and sophisticated tools and analysis methods allow us to perform a structured concept development, feasibility assessment or preliminary design. In other project phases, it enables us to reliably assess vendor designs and provide our technical verification as subject matter experts. This helps reduce unnecessary design conservatism and ensure long-term fatigue resistance during design or life extension projects.

Our substantial experience means we can minimise analysis requirements, methods and computational power to process vast load case matrices quickly and reliably to help us optimise flexible riser configurations efficiently. We also have advanced methods for flexible riser fatigue analysis that offer the benefits of a more realistic random sea global analysis as opposed to a conventional and often over-conservative regular wave/histogram approach. Time-domain finite element cross-section analysis using BFLEX for flexibles and UFLEX for umbilicals helps us determine local tensile and pressure armour wire stresses and perform rainflow fatigue calculations.

Equipment Engineering & Delivery Management

Being independent of manufacturers, we work with operators and installation contractors to ensure that vendor-developed flexible pipe and umbilical solutions are suitable for their intended service. We also target transparent design and support the development of thorough documentation, which facilitates future engineering assessments should actual operating conditions change.

We provide delivery management support from the preparation or verification of material and manufacturing specifications through all stages of purchasing, manufacturing, material and component testing, transport and installation. We also support retrieval and decommissioning projects.

With an extensive subsea equipment engineering track record, we engineer system-specific ancillary equipment, including buoys, arches and tethers. We can also manage the design and manufacture of generic equipment such as bend stiffeners and end terminations.

Flexible Riser Integrity Management & Life Extension


Extensive industry research on flexible pipe degradation in recent years has provided invaluable inputs that can now be applied to risk-based assessments for flexible pipelines and risers to improve integrity management.

2H has developed and optimised testing, inspection and monitoring programmes to better detect structural degradation of critical components and interfaces and measure flexibles and umbilical integrity. Our experience includes managing flexible pipe non-metallic materials compatibility testing, metallic wires fatigue testing and investigative dissection of flexible pipe sections retrieved from the field. We have contributed to and led flexible pipe root cause investigations by applying a methodological approach and independently leading a process that has contributed to a unique in-house knowledge base.

Machine learning algorithms are now helping us manage in-service flexible risers. Through the integration of global and local flexible riser analysis models, we have developed methodologies to predict flexible riser fatigue at key locations using trained algorithms and real-time measured data. This allows for accurate riser monitoring and management without installing sensors on the riser. Read more in this paper: Machine Learning for Riser Engineering.

Flexible Riser Annulus Testing

engineering usine flexible riser annulus test kit

For flexible risers that are nearing or exceeding their original service duration, we evaluate remaining fatigue life to support life extension and potentially prevent costly replacement. This is achieved by performing flexible pipe annulus testing to determine annulus condition, along with both global and local analysis.

To enhance our flexible riser integrity management capability, we developed FlexTest, our in-house flexible riser annulus testing kit. FlexTest is an easily transportable package that can safely and efficiently perform API 17B compliant annulus testing. It assesses the condition of the outer sheath, the most vulnerable layer of a flexible riser. Our test kit will perform testing of vent port functionalities, gas sampling or metering, vacuum or positive pressure annulus tests. It can help detect a breached outer sheath and enables a measure of the free annulus volume and estimate of the annulus filling rate due to permeation and condensation (with regular testing).

FlexTest has overpressure protection and is built with high-precision and regularly maintained valves, regulators, flowmeter and datalogger, and has no external power requirement (as base case).

Our test data is evaluated by independent flexible riser specialists, who provide a thorough appraisal of the results and follow up with integrity-related recommendations. We also have extensive experience witnessing and evaluating annulus test results from others on behalf of operators.

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Key Services

  • Owner’s engineering services & independent engineering assurance
  • Market intelligence and strategic technology assessment
  • Conceptual and preliminary design
  • Independent design verification: multidisciplinary and experienced team
  • Global riser configuration
  • Cross-section definition, design and verification
  • Global strength and fatigue analysis
  • Local cross-section strength and fatigue analysis using Bflex and Uflex (regular and irregular wave approach)
  • Riser, umbilical and mooring line interference assessment
  • Ancillary equipment design
  • Fabrication and testing support and witnessing
  • Procurement and fabrication management
  • Installation engineering, including analysis, procedures and ad-hoc solutions
  • Onshore and Offshore site engineering support
  • Independent integrity recommendations for inspection, monitoring & repair
  • Annulus testing execution, witnessing or results evaluation
  • Integrity management, dissection management and failure investigation
  • Re-use, repurpose and life extension assessment

Select Project Experience

Concept, Preliminary, Pre-FEED & FEED Design

  • Equinor – Bay du Nord – Feasibility and Preliminary Flexibles Engineering
  • KBR / BP – Tortue Ph.2&3 Flexible Risers & Umbilical System pre-FEED
  • McDermott / BP – Tortue Ph.1 Flexible Risers & Umbilical FEED Verification and Completion
  • Tullow Ghana – Jubilee SE – Feasibility and Preliminary Flexibles Engineering
  • PremierOil – Flexible Risers, Flowlines & Umbilicals FEED Eng Support
  • Total Angola – Girassol Conceptual Flexible Riser Engineering and Feasibility Assessment
  • First E&P – Nigeria Flexible Risers pre-FEED and Configuration Definition
  • Murphy – Block-H FLNG flexible riser FEED
  • BHGE/Wellstream – Dai Hung Flexible Riser Global Analysis
  • Perenco – Su Tu Nau flexible riser feasibility assessment

Detailed Design, EPCI & Installation Engineering Assurance

  • VAALCO – Etame Field Reconfiguration Flexible Engineering and Procurement Support
  • McDermott / BP – Tortue FLNG Flexible Risers & Umbilical Detailed Riser Engineering
  • Tullow Ghana – TEN Flexible Riser Engineering and Delivery Management Support
  • Petrobras/BakerHughes (over 15 fields) – Ultra-deepwater Pre-Salt FPSOs  – Strength, Fatigue and Interference
  • Petrobras – Campos Basin Installed riser support loads (12 platforms)
  • OGX – OSX2 and OSX3 flexible riser engineering and delivery management support
  • CNOOC – Liuhua Independent Design & Analysis of Flexible Risers, Dynamic Cables, Umbilicals & Mooring System
  • McDermott – Reliance KGD6 Flexible Riser and Pipeline Installation Engineering Support
  • KPOC – KBB Flexible Riser Local Fatigue Analysis
  • OIS – Lufeng Flexible Riser Installation Support

Integrity Engineering & Life Extension

Other Content & Industry Contributions

2H is an active industry contributor and believes in sharing experience for the continuous development of the flexible pipe industry.