Jacketed Line Coupling for Thermal Expansion Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conduits used in manufacturing processes to convey materials at different temperatures face failure due to thermal expansion, leading to fatigue and reduced lifespan, especially in sanitary applications where stainless steel is used, as the thermal coefficient of expansion causes stress and potential rupture during repeated heating and cooling cycles.
Innovation Solution
A slip coupling assembly is used with an inner and outer coaxial pipe, featuring an annular plate for a liquid-tight seal at one end and a slip coupling that accommodates thermal expansion by allowing axial movement between the inner and outer pipes, utilizing elastomeric seals to maintain a seal while allowing for thermal contraction and expansion, which can be retrofitted into existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stainless steel conduits are used to convey materials at different temperatures, then the conduit maintains structural integrity and hygiene, but thermal expansion causes stress and fatigue during repeated heating and cooling cycles
Solution Approach 1:
The conduit is divided into separate inner and outer conduit sections that can move independently relative to each other. The inner conduit is separated from the outer conduit by a slip coupling assembly that allows thermal expansion and contraction without transferring stress between the conduits, thus preventing fatigue cracking while maintaining structural integrity
Solution Approach 2:
A slip coupling assembly acts as an intermediary between the inner and outer conduits. This assembly includes a slip tube that fits over the inner conduit and can slide axially within the outer conduit, allowing thermal movement while maintaining liquid-tight seals through elastomeric seals, thereby mediating the thermal stress without direct rigid connection
2Length of stationary object
If the conduit length is increased to accommodate long conduit runs, then the conduit can cover greater distances, but thermal expansion becomes more pronounced and causes greater stress
Solution Approach 1:
The slip coupling assembly introduces dynamic movement capability into the otherwise static conduit system. The slip tube can slide axially within the outer conduit to accommodate thermal expansion and contraction, allowing the long conduit run to change length dynamically with temperature changes without generating excessive stress
3Strength
If rigid welding is used to connect inner and outer pipes, then the connection is strong and liquid-tight, but thermal expansion causes fatigue and rupture at the weld joints
Solution Approach 1:
The rigid welded connection is replaced by a segmented slip coupling assembly where the inner conduit connects to the slip tube (which can slide), and the outer conduit remains separate. This segmentation allows the connection to maintain liquid-tight integrity through elastomeric seals while accommodating thermal movement, preventing fatigue at connection points
Solution Approach 2:
Elastomeric seals in the form of flexible rings are used to provide liquid-tight sealing between the slip tube and outer conduit, and between the slip tube and inner conduit. These flexible seals accommodate axial movement and thermal expansion while maintaining sealing integrity, replacing the need for rigid welded connections
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 slip coupling assembly effectively extends the lifespan of conduits by accommodating thermal cycling without subjecting them to damaging stress, maintaining a liquid-tight seal and ensuring concentric alignment of pipes, even with large temperature variations and long conduit runs.
Implementation Method 1
Due to the phenomenon of thermal expansion, solid conduits will become longer when temperature is increased, and shorter when temperature is decreased
Implementation Method 2
The O-rings of the outer element slide on a raised land of the inner element, forming a seal which provides for axial movement between the inner and outer pipes
Data Source
AI summary
A conduit assembly has a slip coupling arrangement which allows two separate process or product flow streams with differential temperatures to flow side by side while subject to repeated cycles of thermal expansion and contraction. An inner pipe extends through an outer pipe with an annular plate welded therebetween as a liquid-tight seal at an assembly first end. A slip coupling outer element is fixed to the outer pipe at a second end and has two O-rings engaged within grooves. A slip coupling inner element is fixed to the inner pipe and extends within the outer element with a land which engages the O-rings, allowing thermal expansion and contraction of the conduit assembly with the inner element moving axially with respect to the outer element while retaining a liquid tight seal therebetween. For large temperature variations or long conduit runs, the slip coupling may be longer with polymer slider rings.