Extrusion resistance under high pressure

Resistance to Extrusion of Seals Under High Pressure... 

In high pressure sealing in the oil field service, it should be noted that hardness, modulus, extrusion resistance and resistance to blistering under rapid decompression can all be increased with an improvement in cross link density. However the elongation is reduced, the elasticity diminished and so the sealing potential is lessened. 

Medium Pressure Axial Screw Extruders Axial screw extruders normalty operate with low (see Section 8.4.1) or high (see Section 8.4.3) pressure. The basic principle of an axial screw extruder was shown in Fig. 6.4b.1 (Chapter 6) and Fig. 8.24 (Section 8.4.1). The pressure that is developed by the screw(s) depends on the power of the drive and the frictional resistance in the extrusion channel or other discharge device. Axial screw extruders that rely solely on the pressure developed by the rotating screw(s) employ hydrostatic pressure as the driving mechanism for extrusion. Such machines generally use high pressure. However, under certain conditions and for specific applications, some can be classified as medium-pressure agglomerators. 

The extrusion body used in the production of continuous-column ceramic products is, by nature, highly kneadable and workable. Permanent deformation takes place due to the effects of external forces that induce states of stress within the material as soon as a certain boundary stress is exceeded. This kind of behaviour is summarized under the heading plasticity . The body s intrinsic dimensional stability, i.e. its resistance to creep induced by its own weight, stems from the presence of the aforementioned boundary (or minimum) stress, which in the case of pure shear flow is termed yield point or flow limit . The flow limit indicates at which applied pressure the body begins to flow. 

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