CORNER RELIEF PRESSURE BALANCED EXPANSION JOINTS
FOR GEOTHERMAL POWER PLANT

For installation on a turbine inlet and a turbine outlet in a geothermal power plant in Iceland, Belman designed and manufactured two Corner Relief Pressure Balanced Flexible Joints and one rectangular Compensator.

CLIENT ISSUE
For a project in a geothermal power plant, the client needed a manufacturer able to design and manufacture the Corner Relief Expansion Joints as well as the box-shaped Expansion Joint (rectangular Expansion Joint) and therefore approached Belman with their request. The client had made some very clear specifications for Belman to work with and, through several online meetings as well as adjusted technical requirements, solutions were found to suit the available space and acceptable forces on both the inlet and outlet side of the turbine.

BELMAN SOLUTION – Corner Relief Pressure Balanced Expansion Joints and a Box–Shaped Expansion Joint 
After having forwarded the specifications, the client and their end client requested an online meeting with Belman’s Expansion Joint experts to discuss the Expansion Joint designs. Based on the meeting and the specifications, Belman designed two different Expansion Joint solutions to meet the client request:

Corner Relief Pressure Balanced Expansion Joints
For the turbine inlet, the client needed two Corner Relief Pressure Balanced Expansion Joints able to absorb axial and lateral movement in combination. For that reason, the Corner Relief Pressure Balanced Expansion Joint has two bellows in the inlet, enabling it to absorb lateral movement as well. Corner Relief Pressure Balanced Expansion Joints can be designed for axial or lateral movement absorption alone or for absorbing axial and lateral movement in combination, as in this case. The advantages of introducing Corner Relief Pressure Balanced Expansion Joints are that no pressure reaction force is transmitted to the piping system and the steam turbine, as it is balanced inside the Expansion Joint. Only the spring rate, which is needed to move the Expansion Joint, is transmitted to the piping system. Another advantage is the reduced need for reinforced fix points and guides, as well as their complexity being reduced, as the loads acting on them are reduced. The solution is designed to work under pressure as well as full vacuum. Due to the placement of the Corner Relief Pressure Balanced Expansion Joints, drains were installed to ensure that any condensate which gathered in the balance chamber could be evacuated safely.

Rectangular Expansion Joints (box-shaped Expansion Joints)
For the turbine outlet, which is a non-pressurised steam escape line, the client needed a box-shaped Expansion Joint designed to absorb axial and lateral movement in combination. For that reason, the Rectangular Expansion Joint has two bellows. It is designed with single mitered corners as per client request. The flanges needed to be custom-built, as the hole pattern is specially placed to fit the holes on the mating flanges of the turbine and in the duct of the geothermal power plant. Rectangular Expansion Joints have the same functions as circular Expansion Joints. They were chosen solely for the fact that the Compensator needed to match the structure of the ducting which, in some cases, like here, is rectangular. Furthermore, due to high flow velocity, inner sleeves were introduced to protect the convoluted bellows and smoothen the duct’s inside surfaces.

Member of EJMA
Not only has Belman designed these Expansion Joints according to EJMA, Belman is also an active member of EJMA (Expansion Joint Manufacturers Association). EJMA is recognised as the world’s leading authority for the proper selection and application of Metallic Expansion Joints. As a proud member, Belman not only designs and manufactures our Expansion Joints to meet the guidelines and practices set forth by this association, but is also part of the technical committee preparing the EJMA standards.
Read more about EJMA here: EJMA

Belman – highly experienced in custom Expansion Joints
Belman brings unparalleled expertise in designing and manufacturing custom Expansion Joints, no matter the design and type. Having designed and manufactured 900,000+ Compensators for various industries all over the world, Belman is the go-to company for custom Expansion Joints. The robust Belman track record includes projects involving, but not limited to, Tee Junction Pressure Balanced Expansion Joints as well as Rectangular Expansion Joints. Likewise, Belman is highly experienced in Expansion Joints for geothermal power plants as well as steam turbine applications.