Challenges
The design of subsea rigid pipeline is complex due to the involvement of multiple inter-disciplinary engineering interactions namely flow assurance, material selection, geotechnical, welding, installation, pipeline engineering, and many others. Therefore, it’s demanding in terms of man-hours and engineering resources (skilled manpower and software) involved.
A significant number of engineering hours are spent during pipeline design from Front End Engineering Design (FEED) to detailed design stages. The end-user – operator - supplies an extensive amount of information and data, created by spending a significant amount of time, effort, and expense. This is supplied to various contractors, viz. EPCI, Engineering house, and a 3rd party verifier.
Within the contractors, it is paramount to control the exchange of relevant data between teams and within the team for the project’s benefit. The engineers use data for designing a pipeline for the various failure modes analysis, using in-house design spreadsheets (Excel/Mathcad) or advanced numerical software e.g. Abaqus, Ansys. The extensive analysis and reported results are reviewed, checked, and approved as a part of a quality check. Any change in Basis of Design (BoD) during design or after initial design requires significant time to re-run the analysis, reporting, and quality check.
The slow and low-value manual process can be eliminated by consolidating a centralized database integrated with design software on a single platform. The one-way data flow during design is beneficial to the project, as all involved parties share relevant information via a centralized database.
iDG10 State-of-art solution
iDG10 has developed an innovative state-of-art platform called SPDT (Subsea Pipeline Design Tool) for centralized data storage and data distribution to various subsea pipeline engineering tools (analytical and FE based) to perform detailed design. The platform allows users to digitize the BoD by creating a centralized database and integrating it with the pipeline design suite, namely wall thickness design, on-bottom stability analysis, free-span analysis, cathodic protection design, expansion analysis, lateral buckling, and various other computational modules. These design modules are prepared with consideration of the requirements of subsea pipeline standards e.g. DNVGL-ST-F101 and relevant recommended practices. The SPDT centralized data storage and data distribution approach allows the data owner to control and maintain consistency in the use of up-to-date project data by all parties in the given project.
The platform also incorporates embedded finite element modules to perform offline pre and post-processing tasks, allowing users to save on software licensing costs related to the “Pay as Used” subscription.
The SPDT digitized platform is primarily designed to integrate data and the design tool, making it easy to use in performing various design analysis in parallel with an aim to optimize and simplify the engineering scope. The centralized data storage and data distribution approach allows data owners to control and maintain consistency in the use of up-to-date project data by all parties in the given project. Thus, it avoids the use of redundant data and unnecessary time spent in finding relevant data for analysis.
iDG10 software SPDT is user-friendly and cost-efficient pipeline data management and design suite. The software is unique in its ability to handle frequent and significant changes in the design data quickly and efficiently. The same model can be used from the FEED through final design for analysis, re-analysis, and modification. This digitized platform is primarily designed to integrate data and the design tool, making it easy to use in performing various design analysis in parallel with an aim to optimize and simplify the engineering scope. The SPDT is equipped to generate a report after completion of the relevant analysis, which reduces unnecessary time in checking design data and results. It creates consistency in the reporting and efficiency of the design team. Improved efficiency means the company can reduce the lead time and increase project profit.
SPDT Introduction
Digitized Pipeline design system allows users to create a project-specific centralized database and provide seamless integration with the pipeline design tools, thus allowing the unidirectional flow of information.
The database comprises of these pipeline design inputs:
Pipeline Route Co-ordinate
Pressure and Temperature Profiles
Pipeline Material Properties
Fluid Composition
Coating details
Seabed profile
Crossing details
Trenching details
Soil properties
Metocean Data
The SPDT, a digitized platform integrates the following analytical and advanced FEA (Finite Element Analysis) tools with the centralized database. These modules are developed with the consideration of the requirements of the relevant international standards.
Analytical Design Tools
Wall Thickness Calculation as per DNV-OS-F101/API 1111/NEN3650
On Bottom Stability Assessment as per DNV-RP-F109
Free Span Assessment as per DNV-RP-F105
Lateral Buckling Analysis as per DNV-RP-F110
Upheaval Buckling Analysis as per DNV-RP-F110
Pipeline Safety Analysis – DNV-RP-F107
Cathodic Protection Design as per DNV-RP-F103
Flange Design – Pressure Vessel D0701
Bathymetry Processing
Project Cost Analysis
Advanced Design Analysis Tools (FEM)
Pipe Lay Assessment
On-Bottom Roughness Analysis
Expansion Analysis
Riser-Spools Design Assessment
Lateral Buckling Analysis
Upheaval Buckling Analysis
Crossing Design Analysis
Seismic Assessment
SPDT Database
The SPDT database allows users to create a project-specific database required for the subsea pipeline design analysis. The database creates a folder for each input parameter (e.g. Pipe Dimensions, Operating condition, Soil properties) at a user-defined location and saves the relevant ASCII file. Every change in the input parameters is saved as a new revision for the data traceability purpose. The data has a unique interlock system and cannot be altered without the permission of the originator.
Analytical Design Tools
Pipeline Wall Thickness
Subsea Pipeline wall thickness plays a significant role in mitigating the risk of loss of mechanical integrity and pipeline failure. Factors that affect the pipeline wall thickness must carefully consider in calculating and selecting the economic thickness for pipelines.
The SPDT wall thickness module is developed with the consideration of the requirements of the commonly used subsea pipeline design code DNV-OS-F101 and other standards such as API 1111 & NEN3650. This module allows engineers to perform wall thickness calculation either in single or batch (multi) modes. In the batch mode, various sections - categorized as per the safety class and water depth - of the pipeline can be analyzed in one run. The design report is then automatically created by the system.
On-Bottom Stability
On-bottom stability (OBS) of the exposed pipeline is one of the key factors that affect the design and installation methodology of subsea pipelines. Due to the uncertainties involved in the waves, currents, and soil conditions, accurate on-bottom stability assessment of pipelines plays a vital role in ensuring the long-term integrity of the subsea pipelines. On-bottom stability consists of vertical stability and dynamic lateral stability.
The subsea pipeline OBS requirements are well defined in the widely used DNV-RP-F109 standard. The OBS module within the SPDT platform is designed to carry out a batch run for the pipeline stability assessment of the various sections of the pipeline. The module receives required input data from the centralized database to perform user-defined generalized or absolute stability analysis and confirms required pipeline submerged weight and mitigation action (e.g. Concrete thickness, Rock Dumping) for the pipeline stability.
The other analytical design tools specified above have the same design capabilities and have been validated on various projects.
Advanced Design Analysis Tools (FEM)
On-Bottom Roughness Analysis
The pipeline on-bottom roughness analysis is conducted after installation to determine the free spans along the pipeline route to compare against the allowable free spans estimated as per DNV-RP-F105. The results facilitate to define of intervention requirements at the free spans outside the design criteria.
The SPDT advanced design analysis OBR module, embedded in ANSYS, allows engineers to configure the pipe seabed model and analyse results through user-friendly pre-processing and post-processing user interface. The post-processing interface provides plots of the pipe-seabed interface showing the free span sections along the pipeline route.