LOW REACTION FORCES AND
LOW SPRING RATES
WITH 3 HINGE SYSTEM
Three customised Angular Expansion Joints have been delivered for a project in Northern Europe. They will be installed in a pipe routing between two condensers.
The client sought out expert advice from Belman and its local partner in order to find the most technically and commercially attractive solution for their problem. They needed to combine an existing condenser with a new one using a piping route. Expansion joints would be required to absorb movements, it was also of high importance that both reaction forces and spring rates would be kept low.
Solution & Benefit
Normally in such conditions a pressure balanced expansion joint would be the best solution. However, as the client had sufficient space between the condensers, Belman proposed a solution utilising a three-hinge system, also known as U-pipe or 3 pin system (More information about U-Pipe can be seen in the Belman Expansion Joint Catalogue on page 71). After further analysis, this proposal was confirmed as the most technically and cost-efficient solution for absorbing the movements. This solution consists of three angular expansion joints with hinges. With the selected placement and constellation of the expansion joints in the three-hinge system, the reaction forces and spring rates were maintained at an acceptably low level. Additionally, the hinged expansion joints were further designed to carry the weight of the pipes connecting the expansion joints. The Expansion joints types, piping constellation and design of the piping resulted in both the optimisation of the solution and the subsequent costs.
Benefits of the Three-hinge system:
- Larger movements can be absorbed
- Substantial fix points and guides in the piping route are no longer needed. This is due to the pressure thrust force from the bellows being contained by the hinge structure on the expansion joints.
- The expansion joints with hinges are able to absorb external forces (such as the weight of intermediate pipes) along with the pressure thrust from the medium.
Amended Catalogue items
The Angular Expansion Joints with hinges are a customised solution. However, these expansion joints are based on the Angular Expansion Joints shown in the Belman Catalogue – ID no. 65.080.10 – which have been adapted to meet the client’s request. As the three hinge system is installed horizontally the gravitational force of the intermediate pipes are perpendicular to the plane of the movements. To verify that the hinge construction is suitable to carry the load of the intermediate pipes, a Finite Element Analysis of the hinge construction was made.
Design parameters of the Angular Expansion Joints with hinges
The Angular Expansion Joints with hinges have the following design parameters:
Dimension: DN 1000 • Length: 636 mm • Medium: Steam • Design temperature: 120°C • Design pressure: Full vacuum/0,49 barG • AN: +/-11° • Bellows: 1.4571 • Inner sleeve: 1.4541 • Pipe end, hinge plate: 1.0425