Expansion joints - from Nortesco
Purpose & Application:
Expansion joints are vital components in most industrial plants.
They are installed as flexible connections in duct and pipe systems
to prevent damage caused by variations in temperature, pressure
or mechanical stress due to movement or vibration.
- Conventional power plants (oil, gas, coal-fired)
- Gas turbine and combined cycle systems
- Flue gas cleaning systems
- Diesel engine installations
- Petro-chemical plants
- Processing plants (steel works, cement works etc.)
- District heating systems
- Chemical plants
- Offshore installations
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When selecting the right expansion joint for the application,
a number of important factors must be considered (see
Data Sheet/Inquiry Form):
- operating conditions of the plant
- necessary chemical or thermal resistance levels
- requirements for pressure resistance, noise suppression etc.
- movements in the duct systems and other components
If you consider the duct system of a power plant, you can see
the many different demands that are to be met by the expansion
joints. Rather simplified, the power plant may be subdivided into
a "hot" and a "cold" area. On the hot side,
the temperature load and the loading of the flue gas with fly
ash is decisive. On the cold side, the expansion joint is, above
all, affected by the formation of aggressive condensate, due to
the temperature falling below the dew point.
Chemical or Thermal Resistance
The temperature as well as the medium has important influence
on the choice of expansion joint type, the design, and the construction,
and essentially the design is decided by the type of the medium.
The most important temperature values to consider are: operating
temperature, excusion temperature, variations in temperature,
design temperature and ambient temperature.
Special leakage requirements may be necessary, such as nekal
tightness, flue gas tightness, defined leakage rate, drip-proof,
leakproof, air or dust tightness.
Requirements for pressure resistance
The pressure has important influence on the choice of expansion
joint type and the design. Fabric, rubber and metal expansion
joints have different pressure capacities but pressure requirement
should always be considered in relation to flexibility. Distinctions
are made between positive pressure, negative pressure, variations
of pressure (pulsations), pressure surges, and design or test
Axial compression and elongnation