Pipe Coating Edge Finisher for Moisture-Resistant Subsea Handling
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Solution Overview
Problem
The existing methods for protecting the coatings of pipes used in the oil and gas industry, particularly the 5LPP and 7LPP coatings with alternating layers of solid and foamed polypropylene, are inadequate during storage, handling, and transportation, as they fail to prevent moisture and dust ingress, leading to weak bonding and potential corrosion at the field joint.
Innovation Solution
Applying a thermoplastic edge finisher that is mirror-welded to the cut edge of the coating, using a hot plate to melt and fuse the thermoplastics with the polypropylene, creating a strong and reliable protective layer that adheres to the coating and prevents moisture and dust ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a film tape is applied to protect the cut edge of the coating, then the edge is protected from dust and moisture, but the protection is inadequate and allows moisture and dust ingress during storage and handling
Solution Approach 1:
A thermoplastic edge finisher is introduced as an intermediary component between the coating and the environment. This edge finisher is mirror-welded to the cut edge of the coating, creating a robust protective barrier that prevents moisture and dust ingress during storage and handling operations.
Solution Approach 2:
The protective mechanism changes from a simple film tape application to a thermoplastic material that can be melted and fused to the coating. This parameter change in material properties and application method creates a much more effective and reliable protective barrier.
2Ease of operation
If the coating edge is left exposed after cutting back, then welding preparation is facilitated, but the foamed layers are vulnerable to moisture and dust damage
Solution Approach 1:
The cut edge of the coating is prepared in advance by mirror-welding a thermoplastic edge finisher to it. This preliminary protective action is taken before the pipe is stored or handled, ensuring that the vulnerable foamed layers are protected from moisture and dust ingress during subsequent operations.
3Ease of manufacture
If temporary protection with film tape is used, then the cut edge is protected during handling, but the protection is lost during storage and transportation
Solution Approach 1:
The patent replaces the disposable film tape with a more durable thermoplastic edge finisher that is mirror-welded to the coating. This edge finisher provides long-lasting protection throughout storage and handling operations, eliminating the need for temporary protection that is easily lost.
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 edge finisher provides a robust and durable protection that prevents damage to the foamed layers, ensuring better adhesion and mechanical protection, reducing the risk of corrosion and improving the longevity of the coating during storage and transportation.
Implementation Method 1
heat being applied to melt the thermoplastics of the edge finisher and the polypropylene of the coating at their interface to fuse the edge finisher with the coating
Implementation Method 2
heat being applied to melt the thermoplastics of the edge finisher and the polypropylene of the coating at their interface to fuse the edge finisher with the coating
Data Source
Figure 1~3
Figure 4a~4c
Figure 5a~5c
AI summary
A method of protecting a layered coating on a length of pipe for subsea use comprises applying an edge finisher to the coating to encase an edge of the coating by fusing the edge finisher with the coating or by moulding the edge finisher at an edge of the coating. Where the coating and the edge finisher are of thermoplastics such as PP, fusing may be achieved by injection moulding the edge finisher or by welding a discrete edge finisher component to the edge of the coating. Mirror welding may be employed for this purpose, with a hot plate being interposed between the edge of the coating and the edge finisher.