Compact Pressure Balanced Expansion Joints
The Downer Energy Systems' (DES) compact pressure balanced expansion joint was originally developed for application in the power generation industry. The requirement was for an extremely compact arrangement that allowed equipment movements to be isolated from adjoining piping. At the same time an alternative was sought to conventional metal bellows which experience deterioration and failure due to corrosive media and cyclic loading.
The pressure-balanced bellows allows equipment or piping movements to be accommodated and ensures that pressure thrust is not transferred to the adjoining equipment or piping.
Operating experience has confirmed the exceptional reliability of this product. This type of expansion joint is an ideal replacement for troublesome expansion joints of alternative design.
Downer Energy Systems have supplied a large number of compact pressure balanced expansion joints to the power generation industry in Australia. A typical application of the DES pressure balanced expansion joint is in the connection of the main cooling water pipes to steam surface condensers in large power generation units.
Advantages- Minimises load on critical equipment due to pressure thrust and thermal expansion
- Extremely compact, In-Line design allows for greater flexibility in layout of plant. The DES pressure balanced expansion joint can be used in either horizontal or vertical applications
- Exceptional reliability
- No steel components in direct contact with the operating media provides good resistance against a wide range of corrosive media
- More cost effective than other conventional designs
- Wide Range of sizes to suit client requirements
- Internal surfaces of all carbon steel components are epoxy lined
- Design of pressure retaining components in accordance with Australian Standard AS4041- Pressure Piping
- Design Conditions 590 kPa (gauge) at 60oC
- Flanged ends in accordance with AWWA Class B
- Assembly can be supplied with welding end connections
- Optional rubber lining of carbon steel parts
- Design to ASME or other internationally recognized codes
- Special Applications and variations on request
- Intermediate sizes and alternative pressure ratings available on request
- Super compact reduced overall length versions available
The Compact Pressure Balanced Expansion Joint features a rubber bellows in the main piping (1). The convoluted rubber expansion bellows (1) allows for piping or equipment movement in both longitudinal and transverse directions. In order that the pressure thrust generated by a "free piping end" does not transfer to the plant equipment, an opposing force is applied to the piping via means of rubber bags (2) which act on a sliding flange (3).
The total cross sectional area of the rubber bags acting on the sliding flange (3) is equal to the cross sectional area of the rubber expansion bellows (1). The rubber bags are connected to the main cooling water piping via adequately sized rubber hose (6) thereby allowing the bags to operate at the same pressure as the main piping. In this way an equal but opposite force is transferred through the stayrods (4) to counteract the pressure thrust which would otherwise transfer to the adjoining equipment.