Belman Tests Corner-Relief Expansion Joints for Swedish Nuclear Plant

Belman has recently created and tested six corner-relief expansion joints with ring reinforcement for a Swedish nuclear power plant.

The expansion joints are installed by the pumps, which are operating at a pressure of up to 145 barg.

Limitation of reaction forces on the nozzles

The challenging operating conditions influenced the design criteria. These conditions included an extremely high pressure of 145 barg, movements and a very low permissible load that could be generated by the expansion joint onto the pump nozzles. These design criteria set high demands for the expansion joint solution, which had to be tested at +200 barg.

Expansion joint design to suit the requirements

The nuclear power plant expected a solution which would incorporate 6 sets of two lateral expansion joints with spring hangers in between. Instead, Belman proposed 6 corner-relief expansion joints with ring reinforcement that could absorb the loads and movements, save space, avoid the spring hangers and prevent the pump nozzles from being damaged. This solution was validated by calculation to check if movements from an earthquake would result in collisions and further verified in the operating environment into which they would be deployed.

How did the client benefit from this suggested design?

With this corner-relief expansion joints with ring reinforcement solution, the nuclear power plant benefitted from:

• A compact, and therefore, space saving solution. This was due to the design which replaced two lateral expansion joints, by building their function into a single expansion joint.
• The elimination of spring hangers in this part of the pipe system.
• Low reaction forces to the nozzles and therefore no unexpected damages on the pumps nozzles.
• A verified and optimized expansion joint solution.
• Reliability of the expansion joint which can operate under high pressure due to the ring reinforcements.
• Guaranteed to deliver safe, reliable and smooth operation.

Heavy units of up to 542kg each

The corner-relief expansion joints with ring reinforcement are relatively small in diameter and have a compact and optimized design, despite this they are still very heavy. The DN 200 has a total weight of 542 kg each with the largest flange weighing 122 kg by itself. The DN 150 expansion joints weigh 383 kg each with the largest flange weighing 72,5 kg alone.

Nuclear power plants and Belman

Belman excels in the design and manufacture of expansion joints for customer specific needs and has completed more than 750.000 expansion joints for various applications. Since 1994 Belman has supplied a wide range of nuclear power plant projects worldwide and therefore our experience in expansion joints for this business area is vast with a long reference list of successfully completed projects.

Design parameters of the corner-relief expansion joints with ring reinforcement

The corner-relief expansion joints with ring reinforcement have the following design parameters:

• Quantity: 3 pcs
• Dimension: DN 200
• Length: 922 mm
• Media: Fully demineralised water
• Design temperature: 70°C
• Design pressure: 145 barg
• AX: +0/-2,94mm
• LA: +0/-7,23mm
• Bellows: 1.4571
• Flanges: 1.4404

Additional design parameters are:

• Quantity: 3 pcs
• Dimension: DN 150
• Length: 1054 mm
• Media: Fully demineralised water
• Design temperature: 70°C
• Design pressure: 145 barg
• AX: +0/-3,86mm
• LA: +0/-7,61mm
• Bellows: 1.4571
• Flanges: 1.4404