Flexible Pipe End Fitting Plasticizer Extraction
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Solution Overview
Problem
Flexible tubular pipes used for hydrocarbon transport experience a loss of mechanical properties and dimensional changes due to plasticizer exudation, leading to impaired sealing over time, particularly at high temperatures, which existing control devices fail to effectively address.
Innovation Solution
A method involving the formation of an annular chamber inside the pressure sheath's annular border, where a fluid is circulated to extract volatile additives, maintaining dimensional stability and preventing plasticizer migration, ensuring a consistent crimping pressure and sealing integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If plasticizers are added to PVDF-based polymer to improve flexibility and cold behavior, then the pressure sheath becomes more flexible and suitable for low temperature applications, but the plasticizers gradually migrate and exude from the polymer mass, causing dimensional changes and loss of sealing pressure over time
Solution Approach 1:
The patent applies preliminary action by extracting plasticizers from the pressure sheath before the crimping operation. A solvent is introduced into the pressure sheath prior to crimping to dissolve and remove plasticizers in advance, preventing subsequent dimensional changes and sealing pressure loss that would occur during service life
Solution Approach 2:
The patent implements extraction by removing the harmful plasticizers from the pressure sheath using a solvent. The solvent penetrates the polymer matrix, dissolves the plasticizers, and extracts them through capillary channels or drainage paths, eliminating the source of dimensional instability before crimping
2Reliability
If the pressure sheath is crimped to create a seal between the end piece and the sheath, then sealing is achieved, but dimensional changes due to plasticizer migration cause the crimping pressure to decrease over time, impairing the seal
Solution Approach 1:
The patent performs the plasticizer extraction action before crimping, ensuring that the pressure sheath is dimensionally stable at the time of sealing. By removing plasticizers in advance, the crimping pressure is maintained consistently over time without degradation
Solution Approach 2:
The patent applies beforehand cushioning by pre-treating the pressure sheath with solvent to remove plasticizers that would otherwise cause future dimensional changes. This preparatory step cushions against the potential loss of sealing pressure by eliminating the root cause before the sealing operation
3Temperature
If high temperature operation (100°C to 130°C) is required for hydrocarbon transport, then PVDF-based polymer is used to withstand the temperature, but the plasticizers in PVDF-based polymer exude more rapidly at high temperatures, accelerating dimensional changes
Solution Approach 1:
The patent applies preliminary action by extracting plasticizers before service, preventing the high-temperature acceleration of plasticizer exudation. The solvent treatment removes plasticizers in advance, so even when the pipe operates at high temperatures, there are minimal plasticizers left to migrate and cause dimensional changes
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 method ensures a constant internal diameter and shape of the annular border, maintaining the sealing integrity and crimping pressure over time, preventing plasticizer exudation and ensuring a perfect seal between the pressure sheath and the end piece.
Implementation Method 1
a fluid is circulated inside said annular chamber to locally extract said volatile additives from said annular cladding border through said internal wall
Implementation Method 2
a fluid heated to a temperature above 130° C. is circulated inside said annular chamber so as to promote the diffusion of the plasticizers through the thickness of the edge of the sheath
Data Source
Figure 1~3
AI summary
The invention relates to a method and installation (10) for mounting an end fitting on a flexible tubular pipe (12), said flexible tubular pipe (12) having a free end (14) and comprising an internal pressure sheath (24) made of a polymer material containing additives that can be exuded. The internal pressure sheath includes an annular edging (28) and said annular edging includes an internal wall (31) opposite an external wall (33). According to the invention, the installation comprises: means for forming an annular chamber (47) inside the annular edging (28) along the external wall (33); means for forming an annular chamber (47) inside the annular edging (28) along the internal wall (31), said internal wall (31) forming an internal surface portion of the annular chamber; and means for circulating a fluid inside the annular chamber (47) in order locally to extract the volatile additives from the sheath annular edging (28) through the internal wall (31).