PRESSURE BALANCED EXPANSION JOINT
RELIEVING LOADS ON THE PUMP NOZZLES

Belman has designed and supplied a remarkable Pressure Balanced Expansion Joint. It was installed in the paper mass production line of a Swedish producer of solid bleached board. The Expansion Joint was primarily required to relieve the loads on the pump nozzles, however the client also received further benefits from its installation.

 

The Client’s problem

The pulp and paper plant experienced excessive loads on the pump nozzles in a production line pipe system. This led to a decision to reduce these loads through the installation of Expansion Joints. The Expansion Joint solution would need to absorb a combination of both small axial and small lateral movements. However, this would need to be done in a very restricted space were standard solutions, such as Lateral Tied Expansion Joints, would be unviable. This posed the question – which Expansion Joint types could solve this problem and how could they be designed to perform with the optimum effect. Belman through their Swedish partner responded to this challenging question and provided its expert guidance to the client. Based on drawings of the pipeline area and the specifications, Belman proposed an Expansion Joint design that could satisfactorily solve this issue. As the media involved was that of paper pulp, it was crucial that the design would avoid closed spaces were the media could pack up and restrict the correct functioning of the Expansion Joint.

 

Solution

In close dialogue with the client, Belman designed an effective solution. In order to ease the work and verification of the solution for the piping engineers involved, the quotation and design were complimented by Rohr2 data. This quotation package could then be directly implemented into the piping software used by the client.
To resolve the client’s issues, a Pressure Balanced Expansion Joint was specified. Both the axial and lateral movements as well as avoidance of reaction force from the pressure can be handled by the Pressure Balanced Expansion Joint.
Due to the location of where the Expansion Joint would be installed in the pipe system and the presence of the pulp media, a special design was required to combat the threat of packing up. In order to avoid pulp from packing up in the bellow, the convolutions were designed and formed with wide open angles. Furthermore, the coned ends for the balance bellow on the Expansion Joint ensured sufficient flow in the Pressure Balanced Expansion Joint. Combined together, these special design features reduce the risk of the media from packing up, thus eliminating potential damages and interrupted operation.

 

Benefits

With this Pressure Balanced Expansion Joint solution the pulp and paper plant achieved several benefits:

  • No media packing up in the Expansion Joint
  • Smooth operation
  • Relief from high loads on the pump nozzles
  • Optimum handling of multiple movement scenarios
  • Complete stainless steel construction for chemical resistance

 

Design parameters of the Pressure Balanced Expansion Joint

The Pressure Balanced Expansion Joint supplied for the project had the following design parameters:

Dimension: DN 300 • Length: 704 mm • Medium: Paper pulp • Design temperature: 100°C • Design pressure: 7,8 barG • AX: +0/-3,7 mm • LA: +0,3/-0,3 mm • Bellows: 1.4541 • Pipe end: 1.4541 and 1.4404 • Flanges: 1.4404 and 1.4307 • Design code: EN 13445 • Documentation: CE Marked acc. to PED cat. II, module H