Variable-Stiffness Clamp Spring for Even Riser Pressure

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Solution Overview

Problem

Existing clamps for buoyancy modules on tubular members like risers face challenges in maintaining even pressure distribution due to changes in diameter caused by pressure and temperature variations, leading to potential riser collapse or misalignment.

Innovation Solution

A modified clamp spring with an arcuate resilient body featuring varying stiffness and an undulating outer surface with projections and voids, designed to distribute load more evenly across the circumference, reducing peak pressures and preventing tubular member collapse.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rigid clamp is used to secure buoyancy modules on risers, then the clamp provides strong holding force, but the clamp cannot accommodate diameter changes of the riser caused by pressure and temperature variations, leading to potential slip or misalignment

Engineering Contradiction:

Improveholding forceVSAvoidaccommodation of diameter changes

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The clamp incorporates a resilient body that acts as a flexible element between the rigid clamp structure and the riser. This resilient body can deform to accommodate diameter changes of the riser caused by pressure and temperature variations, while the rigid clamp structure maintains the holding force. The flexible resilient shell allows the clamp to adapt to dimensional changes without losing its securing function.

Inventive Principle:

Principle #30Flexible shells and thin films

2Device complexity

If a uniform stiffness clamp spring is used, then the clamp structure is simple, but the pressure distribution on the riser is uneven, causing peak pressures that may lead to riser collapse

Engineering Contradiction:

Improveclamp structure simplicityVSAvoidpeak pressure causing collapse

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The resilient body incorporates varying stiffness along its length, with different sections having different compliance characteristics. This allows the clamp to apply lower pressure at critical locations on the riser (such as the crown and heel areas) while maintaining adequate holding force in other regions. The non-uniform stiffness distribution optimizes pressure distribution to prevent riser collapse without requiring a completely complex clamp structure.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If the clamp is designed to accommodate large diameter variations, then the clamp can handle pressure and temperature changes, but the clamp becomes more complex and difficult to dimension correctly

Engineering Contradiction:

Improveaccommodation of diameter variationsVSAvoidclamp dimensioning complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The resilient body's stiffness characteristics are optimized to provide adequate compliance for expected diameter variations while maintaining a relatively simple clamp structure. By carefully selecting the material properties and geometric parameters of the resilient body, the clamp can accommodate large diameter variations without requiring overly complex mechanisms. The resilient body acts as a passive compensating element that automatically adapts to dimensional changes.

Inventive Principle:

Principle #35Parameter changes

4Stress or pressure

If multiple rigid clamping points are used to distribute load, then the load distribution improves, but the clamp cannot accommodate riser deformation and may cause damage to the riser

Engineering Contradiction:

Improveload distributionVSAvoidriser damage from rigid clamping

Core Design Contradiction:

Stress or pressureVSObject-affected harmful factors

Solution Approach 1:

The resilient body replaces rigid clamping points with a flexible contact surface that can conform to the riser's outer diameter. This flexible interface distributes the clamping load evenly across the contact area while accommodating riser deformation. The resilient material absorbs the compliance requirements, preventing stress concentrations that would occur with rigid clamping points and thereby avoiding damage to the riser.

Inventive Principle:

Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The modified clamp spring ensures a homogeneous pressure distribution around the tubular member, preventing collapse and maintaining the riser's intended configuration despite diameter changes, enhancing the clamp's performance in handling larger buoyancy loads and rough sea conditions.

Implementation Method 1

a spring (5) comprising a resilient body (6) which has an arcuate form when mounted on the clamp component (101)

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4051864B1spring

Publication Date: 2025.01.08 BALMORAL COMTEC

Figure 1
Figure 2A~2B
Figure 3A~3B

AI summary

A spring (5;105;205;305;404;505) for a clamp suitable for attachment to a tubular member, the spring comprising a resilient body (6;106;206;306;406;506) having first and second ends (8;108;208;308;408;508) and an internal surface (7;107;207;307;407;507) adapted to seat within a clamp member and an external surface (9;109;209;309;409;509) adapted to contact the outer surface of a tubular member, the internal and external surfaces extending between the first and second ends and wherein the stiffness of the resilient body of the spring varies over the length of the body between the first and second ends.