API RP 11S7:1993(R2013) pdf download.Recommended Practice on Application and Testing of Electric Submersible Pump Seal Chamber Sections
4.1 Shaft: The shaft transmits torque from the motor to the pump. It also transmits the axial thrust generated by the pump to the thrust bearing. Shaft straightness is fundamentally important in the reduction of vibration and assuring proper function of shaft seals and bearings. ShaR runout of 0.002″ FIM or more between bearing locations is likely to result in unacceptable vibration levels.
4.2 Shaft Seals: Shaft seals are used to seal the inter- face between the shaft and a stationary component. The most commonly used types are elastomeric bellows and metal bellows mechanical face seals. Radial lip seals are sometimes used. 4.2.1 Mechanical Face Seal: The sealing function of the face seal is accomplished by a stationary, primary seal ring bearing against the face of a mating ring mounted on a shaft. Axial pressure maintains the con- tact between the stationary and rotating mating rings. See Figures 4.2 and 4.3 for a description of components. 4.2.2 Raàial Lip Seals: Sometimes used to provide the same function as Mechanical Face Seals. Composed of a “U” shaped stationary elastomeric or plastic ring sealing against the shaft or a shaft sleeve. See Figure 4.4 for a description of components.
4.3 Static seals are installed between surfaces where no relative motion exists. 4.3.1 O-Rings are elastomeric ring type seals used to keep well fluids from entering the seal chamber through housing joints, mechanical seals and flanges. Elastomeric O-rings have become widely used in static sealing applications because of their flexibility and resistance to compression set. O-rings are prone to damage during installation. Care must be taken to insure that the O-ring sealing area is clean and free of scratches across the grooves in order to insure proper sealing. A small amount of lu- brication on the O-ring aids in assembly, but excessive lubrication can defeat sealing ability.
4.7 Labyrinth Chamber (See Figures 4.1& 4.1B, and 4.10: The labyrinth chamber provides a fluid interface between the well fluid and motor oil. Typical designs are the annular and breather tube configurations, as shown in Figures 4.5A and 4.5B. Normally there is a mechanical face seal located at the top of this chamber and mounted on the shaft. Its function is to prevent the well fluid from traveling directly down the shaft and through the cham- ber. For pressure equalization to the well bore, a passage- way is provided in the seal assembly head connecting the area just above the mechanical face seal to the outside annular section (Fig. 4 . W or a breather tube (Fig. 4.1B) of the labyrinth chamber. The fluid flow paths through each chamber design are shown in Figures 4.5A and 4.5B. For the annular design, as the temperature of the unit increases, the fluid expands up the inner annulus tube section formed by the shaft and the shaft tube. At the top of this annulus, the fluid migrates over to the middle annular section formed by the shaft tube and the middle tube. It then travels down this section and up the outer annular section formed by the middle tube and the outer housing. The fluid then travels through the passageway connecting the area above the mechanical face seal. Upon contraction, the fluid follows the reverse path through the chamber.
API RP 11S7:1993(R2013) pdf download
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