Subsea Composite Vessel Weight Reduction

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Solution Overview

Problem

Conventional metallic pressure vessels for subsea separation systems are costly, heavy, and challenging to manufacture and install due to their thick walls, which are necessary to withstand high pressure and temperature conditions in deepwater environments.

Innovation Solution

A composite material-based subsea vessel with a load-bearing structure and a metallic or PEEK liner and flange, utilizing Carbon Fiber Reinforced Polymer (CFRP) or fiberglass for strength, and a galvanic coupling protection to prevent corrosion, along with an external coating for protection, reducing weight and installation costs through additive manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a metallic pressure vessel with thick walls is used to withstand high pressure and temperature conditions, then the strength and reliability are improved, but the weight and manufacturing cost increase significantly

Engineering Contradiction:
ImprovestrengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent applies composite materials (specifically CFRP - carbon fiber reinforced polymer) for the load-bearing structure of the subsea vessel. This composite material provides the necessary strength to withstand high pressure and temperature conditions while significantly reducing the weight compared to conventional thick-walled metallic vessels. The composite structure is designed with specific fiber orientations and layers to optimize mechanical properties for the harsh subsea environment.

Inventive Principle:
Principle #40Composite materials

2Strength

If a metallic pressure vessel with thick walls is used to withstand high pressure and temperature conditions, then the strength and reliability are improved, but the manufacturing complexity and installation difficulty increase

Engineering Contradiction:
ImprovestrengthVSAvoidmanufacturing ease
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The vessel is divided into distinct segments: a liner component and a separate load-bearing composite structure. This segmentation allows each component to be manufactured and prepared independently, with the liner providing the fluid-containing surface and the composite structure providing the pressure resistance. The components are then assembled together, simplifying the overall manufacturing process compared to creating a single integrated thick-walled metallic vessel.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The use of composite materials enables advanced manufacturing techniques such as filament winding and autoclave curing, which allow for precise control of fiber orientation and resin distribution. This results in a structurally optimized vessel that can be manufactured with higher precision and less material waste compared to traditional metallic vessel fabrication processes.

Inventive Principle:
Principle #40Composite materials

3Weight of moving object

If a thin liner is used instead of thick metallic walls, then the weight is reduced, but the ability to withstand high pressure and protect from harsh environment deteriorates

Engineering Contradiction:
ImproveweightVSAvoidreliability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The load-bearing composite structure is designed with multiple layers of carbon fiber reinforced polymer with optimized fiber orientations (including 0°, 90°, and ±45° layers) to withstand multi-axial stress states from high pressure and temperature conditions. This composite structure provides the necessary mechanical strength and environmental protection while keeping the overall wall thickness much smaller than conventional metallic vessels.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The liner acts as an intermediary component between the fluid contents and the composite load-bearing structure. It provides the fluid-containing surface and protects the composite material from direct contact with corrosive or abrasive fluids, while the composite structure provides the primary pressure resistance. This division of functions allows each component to be optimized for its specific role.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4228782B1Subsea composite vessel
Publication Date: 2024.10.16 FMC TECH DO BRASIL
  • EP4228782B1 patent drawingFigure 1A~1C
  • EP4228782B1 patent drawingFigure 2
  • EP4228782B1 patent drawingFigure 3A~3B

AI summary

It is described cylindrical subsea vessel (1) for separation of a flow, the vessel (1) comprising first and second longitudinal ends (T,1"), wherein the subsea vessel (1) comprises: - a liner (2); - at least one fluid inlet (3) and one fluid outlet (4, 5) into and out of an inner volume (7) of the vessel (1); - at least one flange (8) connected in one of the longitudinal ends (1', 1"), wherein the at least one flange (8) and the liner (2) form the inner volume of the subsea vessel (1), and wherein the at least one flange (8) comprises at least one through-going opening (4,5,6) forming the at least one fluid inlet (3,4) and/or fluid outlet (5); - a load bearing structure (9) arranged outside the liner (2) and the at least one flange (8), wherein the load bearing structure (9) is of a composite material. It is further described a method of manufacturing the subsea vessel.