Reinforced Thermoplastic Pipe Liner Bonding Against Gas Permeation
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Solution Overview
Problem
Existing methods for lining metal pipes with thermoplastic materials are prone to gas permeation through cavities and microcavities, leading to potential collapse under pressure fluctuations, particularly in the transport of supercritical CO2 and other corrosive/abrasive media, where rapid gas decompression can occur.
Innovation Solution
A method involving a metal pipe with a thermoplastic inliner coated with a spirally bonded tape containing unidirectional reinforcing fibers, where the tape's adhesive regions adhere to both the inliner and the metal pipe, and the inliner is reduced in cross-section to fit snugly within the pipe, eliminating annular spaces through contact pressure and heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the liner cross-section is reduced by stretching, compressing, or folding to enable insertion, then the liner can be inserted into the pipe, but micro-volumes and cavities remain between the liner and pipe wall due to surface irregularities
Solution Approach 1:
The patent applies thermal expansion by heating the liner after insertion, causing it to expand and fill the micro-volumes and cavities between the liner and pipe wall. This parameter change (temperature increase) transforms the liner from a state with gaps to a state with complete contact, preventing gas permeation while maintaining the ease of insertion achieved through prior cross-section reduction.
2Reliability
If the liner is expanded back to original diameter using pressure and temperature, then the liner seals tightly against the pipe wall, but gas can still permeate through remaining microcavities under pressure fluctuations
Solution Approach 1:
The patent applies a composite material consisting of thermoplastic granules mixed with thermosetting resin. When heated, this composite melts and flows into microcavities, then undergoes thermosetting to form a permanent seal. This composite approach combines the sealing benefits of thermoplastic expansion with the permanent bonding and gap-filling capabilities of thermosetting materials, preventing gas permeation under pressure fluctuations.
3Ease of manufacture
If conventional liner insertion methods are used, then installation is straightforward, but the liner may detach under rapid gas decompression and pressure fluctuations
Solution Approach 1:
The patent applies preliminary action by pre-mixing thermosetting resin with the thermoplastic granules before liner insertion. This preliminary preparation ensures that when the liner is later heated during service, the thermosetting component is already in position to bond with the pipe wall and liner, creating permanent anchors that prevent detachment under rapid gas decompression and pressure fluctuations, while maintaining straightforward installation procedures.
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
This solution prevents gas permeation and collapse by ensuring a tight seal, providing corrosion and abrasion resistance, while maintaining low flow resistance and reducing the risk of inliner detachment, thus ensuring reliable transport of corrosive and abrasive media under varying pressures.
Implementation Method 1
the inliner and the carrier tube are firmly joined together by means of contact pressure and optionally heating
Implementation Method 2
the region of the opposite surface of the tape consists of a molding compound or an adhesive that adheres firmly to the metal of the carrier tube
Data Source
AI summary
The invention relates to a pipe, the inner surface of which is lined with a thermoplastic layer, which pipe is produced by a method comprising the following steps: a) a metal pipe is provided, b) a tubular inner liner made of a thermoplastic material is provided, c) a tape is applied spirally by cohesive bonding to the inner liner, the region of the contact surface of the tape consisting of a moulding compound or an adhesive which adhere firmly to the surface of the inner liner, and the region of the opposing surface of the tape consisting of a moulding compound or an adhesive which adhere firmly to the metal of the pipe, the tape containing unidirectional reinforcement fibres; d) if applicable, the cross section of the inner liner is reduced by the action of an external force, e) the inner liner is introduced into the metal pipe, f) the inner liner and the metal pipe are firmly connected to one another by means of contact pressure and, if applicable, heating. Thus, relative movements between the metal pipe and the inner liner are prevented; moreover, the inner liner has a high resistance to collapsing. The pipe is used for producing a laid pipeline.