Lined Pipe Joining With Insulatory Sleeves for Weld Heat Protection
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Solution Overview
Problem
The existing methods for joining lined pipe sections are costly and time-consuming, especially for shorter lengths, as they require expensive connectors and cooling systems to prevent heat damage to the polymer liners during welding and coating processes, making it impractical for subsea installations.
Innovation Solution
Providing an insulatory sleeve between the pipe lining and the host pipe, which can be made of aerogel or other insulating materials, to reduce heat transfer during welding and coating, allowing for direct welding of the host pipes without extension pieces and enabling the use of electrofusion fittings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connectors and cooling systems are used to prevent heat damage to polymer liners during welding, then the polymer liners are protected from heat damage, but the joining process becomes costly and time-consuming
Solution Approach 1:
An insulatory sleeve is introduced as an intermediary component between the host pipe and the polymer liner. This sleeve acts as a thermal barrier that protects the polymer liner from welding heat without requiring complex cooling systems or expensive connectors, thus resolving the contradiction between protection and efficiency
Solution Approach 2:
The insulatory sleeve serves as a simple, inexpensive protective element that is used during the welding process and then removed. This disposable approach eliminates the need for permanent expensive connectors while still providing adequate heat protection during the critical welding operation
2Reliability
If extension pieces are used to distance liners from welds, then heat damage to liners is prevented, but the device complexity and cost increase
Solution Approach 1:
The protective function is extracted from the complex extension piece structure and embodied in a simple insulatory sleeve. This sleeve can be inserted into the annulus between the host pipe and liner, providing the necessary thermal protection without requiring external extension pieces or complex assembly structures
Solution Approach 2:
The insulatory sleeve is nested within the annular space between the host pipe and the polymer liner. This nested configuration allows the protective element to be integrated into the existing structure without adding external complexity or requiring additional assembly steps
3Reliability
If cooling systems are applied during welding, then heat damage to liners is reduced, but the process time and operational complexity increase
Solution Approach 1:
The insulatory sleeve is installed beforehand during the liner insertion process, before the welding operation begins. This preliminary placement ensures that thermal protection is already in place when welding occurs, eliminating the need for time-consuming cooling system setup and operation during the welding process itself
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 method effectively protects the polymer liners from heat damage during welding and coating, enabling efficient and cost-effective joining of lined pipe sections, even in subsea applications, by providing discrete thermal protection without the need for extensive insulation or expensive connectors.
Implementation Method 1
providing thermal insulation in the annulus between the host pipe and the pipe lining
Data Source
Figure 1
AI summary
In order to reduce or remove the potential risk of heat damage in the absence of cooling jackets when joining lined pipe sections, each lined pipe section (3, 5) is provided with an insulatory sleeve (23, 25) which is disposed between the host pipe (7, 9) and the respective liner (11, 13). The sleeves provide discrete thermal protection to the ends of the liners and, where applicable, electrofusion welds between an electrofusion fitting (15) and the liners (11, 13). The sleeves (23, 25) are first located in the ends of the host pipes (7, 9) which are then lined by drawing the liners (11, 13) through the host pipes via a reduction die to reduce their external diameter. The liners are then reverted towards their original dimensions resulting in a tight fitting against the internal surface of the host pipes and of the insulatory sleeves thereby compressing the insulation material.