Technical requirements and scope of the EN 14917 standard
The European standard EN 14917 establishes strict engineering protocols for the design, manufacturing technology, and installation methods of metal bellows expansion joints. This regulatory framework covers equipment operating in systems with excess pressure exceeding 0.5 bar. Experts at EV Group China emphasize that compliance with this standard is a critical condition for ensuring the reliability of pipeline systems.
Classification and functional characteristics of expansion joints
According to the provisions of EN 14917, bellows expansion joints are divided into four main types depending on the vector of absorbed pipeline deformations:
- Axial expansion joints: designed to level out linear expansions along the pipeline axis. In unrestrained models, the static component of the thrust force is not structurally limited. Versions with internal and external pressurization are available for operation in specific environments.
- Angular expansion joints: provide compensation for angular deflections. The use of hinge mechanisms allows for absorbing displacements in one plane, while the use of cardan connecting rings expands the functionality to operate in multiple planes.
- Lateral (shear) expansion joints: oriented toward absorbing lateral shifts. When integrating two spherical anchor supports, it is possible to compensate for angular deflections in a plane perpendicular to the anchor axis. Equipping them with double hinges or cardans increases system reliability and effectively restrains thrust forces from the medium pressure.
- Universal expansion joints:
- Unrestrained models: capable of compensating for a combination of various displacements, however, they do not neutralize the thrust force generated under pressure.
- Pressure-balanced models: a complex structural system including an additional bellows. Due to the difference in areas or the opposing arrangement of the bellows, a counteracting force is created, neutralizing the load from internal pressure. Recommended for installation at route geometry change nodes, as well as on straight sections with high requirements for support unloading.
EV Group China specialists are ready to provide technical consultation on selecting the type of expansion joint in strict accordance with EN 14917 requirements for your engineering projects.