Two-Layer Pipe Insulation for High-Temperature Reeling
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Solution Overview
Problem
Existing high-temperature polymers used in insulated pipes for subsea oil and gas applications are expensive and inflexible, leading to delamination and failure during reeling due to stress from bending, necessitating a more cost-effective and flexible insulation solution.
Innovation Solution
A molding system that applies two layers of insulation to a pipe, with a thin first layer of high-temperature polymer and a thicker second layer of lower-temperature, more flexible polymer, ensuring the interface temperature remains below the lower polymer's maximum operating temperature and reducing stress during reeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single layer of high-temperature polymer insulation is applied to the pipe, then the pipe can withstand high operating temperatures (350°F or more), but the insulation becomes expensive and inflexible, leading to delamination and failure during reeling
Solution Approach 1:
The insulation system is divided into two separate layers: an inner layer of high-temperature polymer (up to 350°F rating) and an outer layer of lower-temperature polymer (up to 250°F rating). This segmentation allows each layer to be optimized for its specific function - the inner layer provides high-temperature resistance while the outer layer provides flexibility and cost-effectiveness, eliminating the delamination issues that occur with single-layer thick insulation during reeling operations.
Solution Approach 2:
The patent employs a composite insulation structure combining two different polymer materials with complementary properties. The high-temperature polymer (such as PEEK or PTFE) provides thermal resistance capability, while the lower-temperature polymer (such as polyethylene or polypropylene) provides flexibility and mechanical durability. This composite approach allows the insulation system to meet both high-temperature withstand requirements and flexibility requirements for reeling operations.
2Temperature
If a thick layer of high-temperature polymer is applied to provide sufficient insulation, then the pipe can withstand high temperatures, but the cost increases and the insulation becomes too rigid, causing stress from bending during reeling
Solution Approach 1:
Rather than using a single thick layer of high-temperature polymer, the insulation is segmented into two layers with different thicknesses and material properties. The inner high-temperature layer is kept relatively thin (0.125 to 0.250 inches) to provide adequate thermal barrier while maintaining flexibility, and the outer lower-temperature layer provides additional insulation and mechanical protection. This segmentation reduces the overall rigidity and cost while maintaining temperature resistance.
Solution Approach 2:
The patent changes the material parameters by selecting different polymer types for each layer, with specific attention to their glass transition temperatures, flexibility characteristics, and cost profiles. The inner layer uses high-temperature polymers rated for 350°F or more, while the outer layer uses polymers rated for lower temperatures (up to 250°F) that offer greater flexibility and lower cost, optimizing the overall insulation system performance.
3Ease of manufacture
If a single layer of insulation is applied, then the manufacturing process is simple, but the insulation fails during reeling due to stress from bending and delamination
Solution Approach 1:
The patent applies a composite two-layer insulation structure where the inner high-temperature polymer layer adheres to the pipe surface and the outer lower-temperature polymer layer adheres to the inner layer. This composite structure improves reliability during reeling because the outer flexible layer absorbs bending stresses and prevents delamination, while the inner layer maintains thermal performance. The manufacturing process remains relatively simple by applying layers sequentially in separate molding operations.
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 system enhances flexibility and reduces costs while maintaining high-temperature resistance, preventing insulation failure and enabling efficient reeling of insulated pipes.
Implementation Method 1
One or more injectors are configured to inject a first polymer into the first mold cavity
Implementation Method 2
The curable polymer cures to form insulation along the pipe
Data Source
AI summary
A pipe has first and second exterior layers of insulation. The first layer of insulation has a higher temperature rating than the second. The second layer can be thicker than the first. In a system and method for forming the insulated pipe, a first mold having a first inner diameter is used for the first layer of insulation and a second mold having a second inner diameter greater than the first inner diameter is used for the second layer of insulation. The first layer of insulation is formed from a first polymer and the second is formed over the first layer from a second polymer. Multiple insulated pipes can be joined together at field joints and field joint insulation can be formed from first and second layers of field joint insulation corresponding in material and thickness to the first and second layers of pipe insulation.