Flexible joint
SIA WB JOINT
application field
Pressure pipelines where axial restraint is required.
Suitable for pipeline sections exposed to axial forces, such as bends, tees, reducers, end points, steep slopes, crossings or areas with limited space for concrete thrust blocks.
The SIA Wb joint can also be used where belowground or aboveground pipe laying exceeds the standard slope limits. In addition, this joint type is suitable for horizontal directional drilling (HDD) applications, depending on project-specific requirements.
Key specs
| DN range: | DN80–1200 |
| Pressure class / PFA: | 40 bar (DN80–300) 30 bar (DN350–450) 25 bar (DN500–1000) 20 bar (DN1100–1200) |
| Deflection angle (θ): | 3° (DN80–450) 2° (DN500–800) 1.5° (DN900) 1.2° (DN1000) 1.1° (DN1100–1200) |
Sealing principle
The SIA Wb joint is sealed by an XT2 rubber sealing ring positioned inside the socket.
The sealing principle is identical to the XT2-type joint. When the spigot end is inserted into the socket, the rubber sealing ring is compressed and creates contact pressure between the pipe, the gasket and the socket.
Under internal pressure, the lip-shaped sealing ring is pressed more tightly against the contact surfaces. This enhances the sealing eƯect and provides a reliable watertight connection.
Anchoring Principle
The SIA Wb joint combines a flexible sealing system with an integrated self-anchoring system.
The self-anchoring function is achieved through the interaction between the locking-ring components inside the socket and the welding ring on the spigot end. The locking-ring system consists of several locking rings and rubber support bodies, forming a flexible circular anchoring system inside the socket. When axial forces occur, the locking rings engage with the welding ring and transfer the axial load through the joint. This prevents the pipe from being pulled out of the socket while maintaining a certain degree of flexibility and angular deflection.
Joint Features
The SIA Wb joint is a flexible push-in self-anchored socket joint designed to provide both reliable sealing and axial restraint. The locking components are integrated into the socket and engage with the welding ring on the spigot during installation. This allows efficient installation without external bolted restraint components, while providing reliable resistance against pull-out forces.
The joint allows limited angular deflection and can accommodate certain ground movements or settlement. It can reduce or replace the need for concrete thrust blocks in selected applications, depending on the pipeline design and soil conditions.
The SIA Wb joint is therefore suitable for restrained pipe sections, difficult installation conditions, steep slopes, crossings and HDD applications.
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Technical Brochure
Complete overview of our ductile iron pipe range, joint types, coatings, technical parameters and application fields.