Closures and Connectors

In general, the vessel will be tight if the seal pressure (p ) is higher than the inner pressure (pi). Various closure designs have been made to provide the needed seal pressure [21-25]. 

However, the seal pressure cannot be increased without limit. In addition to extrusion of the seal ring between the plug and the wall at pressures higher than 2000 bar, the seal is also pushed to the wall and the plug, which can lead to the deformation or failure of the wall or stem material. 

For corrosive materials, or when the inner fluid should not be contaminated with any kind of seal lubricants, metal-to-metal seals have been successfully employ. In this case, for example, two conical segments impact along a line, making easy opening of the vessel possible. 

Coupling devices to keep the closure in place are often bolted flanges. These flanges have to withstand not only the internal pressure, but also the stress, which is induced by (repeated) tightening. Flanges can be integrally forged 

Outer diameter (in) Inner diameter (jn) od/id ratio Material Pressure rating (bar) 

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