Welding Universal Expansion Joint
DN700
The DN700 Welding Universal Expansion Joint is a high-performance, unrestrained metal expansion joint engineered for demanding pipeline applications. This universal expansion joint comprises two convoluted bellows joined by a central spool piece, with weld end connections that provide a permanent, leak-proof installation. The universal configuration enables absorption of substantial axial, angular, and lateral movements either simultaneously or independently, making it the preferred solution for complex thermal expansion management in large-diameter piping systems.
Delivery
FOB
minimum order
1 piece
Supply Ability
5piece / Month
Country of Origin
China
Stock Time
20-25Day
Quantity:
US $200.00 - US $10000.00
/ piece
## Key Features
This expansion joint is designed with weld ends, specifically beveled for butt welding to ensure a robust and reliable connection. It is available in nominal size DN700, which corresponds to 28-inch pipe diameter. The two-bellow universal design incorporates a central connecting pipe that ties the two bellows elements together, allowing the joint to accommodate multi-directional movements. Pressure ratings are offered in PN 10, PN 16, and PN 25 classes to suit various system requirements. All pressure thrust generated by internal pressure is transmitted directly to the pipeline, which means the system must be equipped with adequate main anchors and pipe guides to handle these loads.
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## Movement Absorption Capabilities
The DN700 universal expansion joint delivers significant movement capacities, which are determined by the specific model and overall length configuration. For axial movements, the joint can accommodate up to 111 millimeters in both compression and extension. Lateral offset capability reaches up to 72 millimeters, while angular rotation can be as high as 15 degrees per bellows element. It is important to note that these movement capacities are alternative rather than cumulative. When multiple movement types occur simultaneously, the combined usage—calculated as the sum of proportional movements—must not exceed 100 percent of the joint's total capability to ensure safe and reliable operation.
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## Materials and Construction
The bellows elements are typically fabricated from high-grade stainless steel, including grades such as 304L, 316L, or 321, selected for their excellent corrosion resistance and fatigue performance. The end connections, central spool, and other structural components are manufactured from carbon steel or matching stainless steel materials, depending on the service conditions. All welds are executed in accordance with stringent quality control procedures, and the completed assembly is subjected to hydrostatic testing and pneumatic leak testing prior to shipment. Optional accessories include internal liners to reduce flow turbulence and erosion, as well as external covers for protection against mechanical damage and thermal radiation.
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## Applications
This expansion joint is widely used in power generation plants, petrochemical facilities, oil and gas transmission systems, district heating networks, and industrial steam lines where large-diameter piping undergoes significant thermal expansion. Its universal design is particularly well suited for applications requiring multi-planar movement absorption, especially in constrained spaces where installing separate axial and lateral expansion joints would be impractical.
---
## Installation Considerations
Proper installation is critical to the performance and service life of the DN700 welding universal expansion joint. The joint must be installed with adequate main anchors at the ends of the pipeline system to withstand the full pressure thrust, along with intermediate guides to prevent buckling and maintain proper alignment. During welding, care should be taken to avoid overheating the bellows; it is recommended to weld the end connections while the bellows are properly protected with heat shielding. The joint should not be subjected to torsional loading or external bending moments beyond its design limits. Prior to commissioning, a thorough inspection of the anchoring and guiding system is essential.
This expansion joint is designed with weld ends, specifically beveled for butt welding to ensure a robust and reliable connection. It is available in nominal size DN700, which corresponds to 28-inch pipe diameter. The two-bellow universal design incorporates a central connecting pipe that ties the two bellows elements together, allowing the joint to accommodate multi-directional movements. Pressure ratings are offered in PN 10, PN 16, and PN 25 classes to suit various system requirements. All pressure thrust generated by internal pressure is transmitted directly to the pipeline, which means the system must be equipped with adequate main anchors and pipe guides to handle these loads.
---
## Movement Absorption Capabilities
The DN700 universal expansion joint delivers significant movement capacities, which are determined by the specific model and overall length configuration. For axial movements, the joint can accommodate up to 111 millimeters in both compression and extension. Lateral offset capability reaches up to 72 millimeters, while angular rotation can be as high as 15 degrees per bellows element. It is important to note that these movement capacities are alternative rather than cumulative. When multiple movement types occur simultaneously, the combined usage—calculated as the sum of proportional movements—must not exceed 100 percent of the joint's total capability to ensure safe and reliable operation.
---
## Materials and Construction
The bellows elements are typically fabricated from high-grade stainless steel, including grades such as 304L, 316L, or 321, selected for their excellent corrosion resistance and fatigue performance. The end connections, central spool, and other structural components are manufactured from carbon steel or matching stainless steel materials, depending on the service conditions. All welds are executed in accordance with stringent quality control procedures, and the completed assembly is subjected to hydrostatic testing and pneumatic leak testing prior to shipment. Optional accessories include internal liners to reduce flow turbulence and erosion, as well as external covers for protection against mechanical damage and thermal radiation.
---
## Applications
This expansion joint is widely used in power generation plants, petrochemical facilities, oil and gas transmission systems, district heating networks, and industrial steam lines where large-diameter piping undergoes significant thermal expansion. Its universal design is particularly well suited for applications requiring multi-planar movement absorption, especially in constrained spaces where installing separate axial and lateral expansion joints would be impractical.
---
## Installation Considerations
Proper installation is critical to the performance and service life of the DN700 welding universal expansion joint. The joint must be installed with adequate main anchors at the ends of the pipeline system to withstand the full pressure thrust, along with intermediate guides to prevent buckling and maintain proper alignment. During welding, care should be taken to avoid overheating the bellows; it is recommended to weld the end connections while the bellows are properly protected with heat shielding. The joint should not be subjected to torsional loading or external bending moments beyond its design limits. Prior to commissioning, a thorough inspection of the anchoring and guiding system is essential.
