Field Joint Coating Stepped Profile for Low-Upstand Pipe Joints
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Solution Overview
Problem
Conventional field joint coatings in insulated pipelines often result in a large upstand, which can damage pipe handling equipment and increase the diameter of the coated joint, making it difficult to handle and reel, especially in offshore applications.
Innovation Solution
The method involves providing angular cut backs in the parent coating of pipe sections, followed by injection moulding a field joint coating to create a stepped profile, resulting in an upstand of 5 mm or less, thereby reducing the volume of coating material and facilitating easier handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the field joint coating is applied using injection moulding to fill the gap and overlap parent coatings, then the field joint is fully coated and protected, but the upstand becomes 8 mm or greater causing damage to handling equipment
Solution Approach 1:
The patent changes the geometric parameters of the parent coating by introducing angular cut backs (first at 30°±5° and second at 15°±5°) to create a stepped profile. This parameter modification allows the field joint coating to be moulded with reduced upstand (≤5 mm) while maintaining adequate overlap and protection, thereby resolving the contradiction between coating protection and equipment damage prevention.
Solution Approach 2:
The patent segments the parent coating into distinct stepped levels through multiple angular cut backs. The first angular cut back creates a primary step, and the second angular cut back creates a secondary step, forming a multi-level profile. This segmentation enables the field joint coating to distribute across different levels, reducing the overall upstand height while ensuring complete coverage and protection of the field joint area.
2Reliability
If the field joint coating overlaps the parent coating significantly, then the field joint is fully protected, but the joint diameter increases making it difficult to handle and reel
Solution Approach 1:
By modifying the geometric parameters through angular cut backs, the patent creates a stepped profile that controls the overlap geometry. The first angular cut back at 30°±5° and second at 15°±5° create controlled steps that limit the radial extent of the field joint coating overlap, thereby reducing the joint diameter and improving handleability while maintaining protective coverage.
Solution Approach 2:
The patent transitions from a simple radial overlap approach to a multi-dimensional stepped profile using angular cut backs. Instead of increasing overlap in the radial dimension only, the solution introduces axial dimensioning through the stepped profile created by angular cut backs at different positions, distributing the overlap across multiple dimensions and reducing the radial protrusion that causes handling difficulties.
3Reliability
If conventional field joint coating is applied with large overlap, then complete coverage is achieved, but the upstand of 8 mm or greater causes damage to pipe handling equipment
Solution Approach 1:
The patent applies parameter changes by introducing angular cut backs with specific angles (30°±5° and 15°±5°) to create a stepped profile in the parent coating. This geometric parameter modification enables the field joint coating to achieve complete coverage while reducing the upstand to ≤5 mm, preventing damage to pipe handling equipment and maintaining both coating reliability and equipment integrity.
Solution Approach 2:
The patent performs preliminary action by creating the stepped profile through angular cut backs in the parent coating before applying the field joint coating. This pre-preparation of the surface geometry ensures that when the field joint coating is injection moulded, it forms the desired low-upstand profile while maintaining complete coverage, thereby preventing equipment damage before handling operations commence.
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 approach allows for a coated field joint with a minimal upstand, enhancing equipment handling and reducing the risk of damage, while enabling more efficient pipeline laying by minimizing the joint's diameter.
Implementation Method 1
injection moulding a field joint coating over the uncoated ends and the first and second angular cut backs
Data Source
AI summary
A method of coating a field joint, pipe sections for forming a coated field joint, and a coated field joint formed thereby. First and second angular cut backs are provided in the parent coating of each pipe section. The first angular cut back is at an angle of about 30°±5° relative to the longitudinal axis of the field joint, and the second angular cut back is positioned further from the field joint than the first angular cut back. The first and second angular cut backs result in the parent coating having a stepped profile, a step in the stepped profile between the first and second angular cut backs, the is substantially parallel to the longitudinal axis of the field joint and is free of indentations. The field joint coating is injection moulded to have an upstand that is less than or equal to about 5 mm.