An Externally Pressurized Expansion Joint takes pressure from the outside of the bellows element rather than on the inside as in a conventional expansion joint. In conventional type of expansion joints with internally pressurized bellows it is not possible to accommodate large axial movements due to the squirm associated with the higher bellows length.
The stabilizing effect of the external pressure increases the bellows capacity to absorb high axial movements without squirm making the externally pressurized expansion joints the best solution for applications involving very high axial movements.
The construction consists of a heavy outer pipe which contains the pressure and serves as a shroud to protect the bellows and also functions as pipe-guide. The outer pipe in externally pressurized expansion joints contains the full pressure of the system and if bellows failure occurs the medium does not escape radially outwards, thus protecting the personnel working in the vicinity.
The construction consists of a heavy outer pipe which contains the pressure and serves as a shroud to protect the bellows and also functions as pipe-guide. The outer pipe in externally pressurized expansion joints contains the full pressure of the system and if bellows failure occurs the medium does not escape radially outwards, thus protecting the personnel working in the vicinity.
As the thermal expansion in externally pressurized expansion joints occurs the bellows element gets extended bringing the internal guide rings closer reducing the gap between them and the medium can flow through this joint as if it were not there.The drain vent and purge connection can be provided in the outer pipe to allow the draining of any sediment or residue that may collect or venting of the expansion joint to assure fluid filled pipeline. The drain connection is also an ideal location for a steam trap for joints used in steam applications.
And since its is totally maintenance free expansion joints can be installed in areas where accessibility is limited. Also since there are no sliding parts there is no need of lubrication or repacking.
The externally pressurized expansion joints provide very low turbulence to the flowing medium due to the fact that the internal surface of the pipeline itself works as the liner for this expansion joint. As the thermal expansion in externally pressurized expansion joints occurs the bellows element gets extended bringing the internal guide rings closer reducing the gap between them and the medium can flow through this joint as if it were not there.