Pipe-in-Pipe Bulkhead Sleeve Joint for Single Offshore Welds
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Solution Overview
Problem
Conventional methods for joining pipe-in-pipe (PIP) pipeline lengths in marine environments require multiple offshore welds, leading to quality assurance issues, increased costs, and potential mechanical weaknesses due to the challenging conditions and time constraints of offshore welding.
Innovation Solution
A PIP pipeline assembly and method that utilize a sleeve with circumferential shoulders and a recess, allowing for a single offshore weld by connecting the outer pipes of bulkheads with a sleeve that has an internal diameter matching the inner pipes, forming an annular space for purging and sealing, which enhances the welding process and reduces the number of welds required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple offshore welds are performed to join PIP pipeline lengths, then the connection is achieved, but the quality assurance deteriorates and the time required increases
Solution Approach 1:
The connection system is segmented into distinct functional components: a coupling device with first and second coupling members, a positioning device, and a sealing device. This segmentation allows each component to perform its specific function independently, enabling the welding process to be broken down into manageable stages that can be performed sequentially with better quality control
Solution Approach 2:
The positioning device performs preliminary alignment and positioning of the pipeline ends before welding occurs. The coupling members are pre-assembled with the positioning device, ensuring proper orientation and spacing. This preliminary action eliminates the need for complex alignment during the welding process itself, improving weld quality while reducing the time required for offshore welding operations
2Reliability
If multiple offshore welds are performed to join PIP pipeline lengths, then the connection is achieved, but the cost increases
Solution Approach 1:
The coupling device serves multiple functions: it positions the pipeline ends, seals the annular space, and facilitates welding. The first and second coupling members can be used with different pipeline configurations. This multi-functionality reduces the number of separate components and operations needed, lowering manufacturing costs while maintaining connection integrity
Solution Approach 2:
The coupling device acts as an intermediary component between the two pipeline ends, providing a controlled environment for welding. The positioning device and sealing device serve as intermediary mechanisms that facilitate the welding process. This intermediary approach allows for better quality assurance without requiring expensive specialized offshore welding equipment or procedures
3Ease of operation
If the internal diameter of the second end of the bulkhead is greater than the first end, then the sleeve can be located within the outer pipe, but the structural complexity increases
Solution Approach 1:
The sleeve is nested within the outer pipe of the bulkhead, with the sleeve's internal diameter matching the inner pipe's external diameter. The first and second coupling members are nested within the annular space created by the varying internal diameters. This nesting arrangement allows the sleeve to be easily located and secured within the outer pipe while maintaining a relatively simple bulkhead structure
Solution Approach 2:
The bulkhead has different internal diameters at different locations: the first end has a smaller internal diameter to accommodate the inner pipe, while the second end has a larger internal diameter to accommodate the sleeve. This local variation in dimensions allows the sleeve to be installed and positioned correctly without requiring the entire bulkhead structure to be complex
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
The present invention provides a pipe-in-pipe (PIP) pipeline assembly for the transport of a fluid in a marine environment comprising: (a) a PIP pipeline length comprising at least metal inner and outer pipes and an annular space thereinbetween, the inner metal pipe having an internal diameter; (b) a PIP bulkhead, having -a first end connected to an end of the PIP pipeline length and comprising at least a metal inner pipe with a first internal diameter, an outer pipe, and an annular space thereinbetween, and -a second end comprising an outer pipe with a second internal diameter, and being able to be joined to a second end of a second PIP bulkhead, wherein the second internal diameter of the second end is greater than the first internal diameter of the first end of the PIP bulkhead. Optionally, the present invention further provides a sleeve at least partly located within the outer pipe of the second end of the PIP bulkhead, and having a sleeve internal diameter being the same or similar to the internal diameter of the metal inner pipe of the PIP pipeline length, and having two circumferential shoulders and a recess between the shoulders, at least one shoulder being within the second end of the PIP bulkhead, and at least one shoulder being beyond the end of the second end of the PIP bulkhead.