Updated 2015 April 16
Sealing device with a self-centering stuffing box
for moving joints of reciprocating and rotary types

Devices with a radially movable stuffing box, designed by private enterprise "Energotehnika" in Kiev, are used to seal the joints of the rotational and reciprocating types for various industrial equipment.

Modernization of traditional gland seals by replacing them with self-centering stuffing boxes has been started since 1994 for many types of centrifugal and plunger pumps used in thermal and nuclear power industry of Ukraine.

In particular, self-aligning stuffing box seals produced by PE "Energotehnika" are implemented for the city heating network pumps SE series, general industrial horizontal pumps type of D and CN, boiler feeding and booster pumps type of PE and PD, vertical condensate pumps brands of KsV and KsVA, vertical high capacity pumps type of OPV, DPV and SDV, pumps such as GrT pumping abrasive slurries, chemical plunger dosing-pumps type of ND and others.

The main advantages of the self-centering seals are 1) their high reliability, 2) a significant increase of equipment operation life, 3) complete absence of unscheduled stoppages for replacing the packing, 4) it is easy to install and maintain the seals. Any modification of equipment for installation of the sealing device is not required.

Several different versions of the self-centering sealing devices are presented below. They all have their particular design features that take into account the specific conditions of the equipment operation, but they all are based on an idea of radially movable stuffing box. The stuffing box with a packing and a gland for tightening the packing are self-adjusted coaxially with a shaft (rod, plunger) and when you turn on the equipment they begin to track the radial vibration of the shaft.

An ease of the stuffing box radial displacement is provided by installing inside the seal housing a separator with balls, which serve as a rolling bearings for the stuffing box and almost eliminate friction against radial shifting of the stuffing box, even with its high dynamic shifts.

For centrifugal pumps at high shaft speeds and in case of its small dynamic displacements, as a bearing for the stuffing box is set in a certain way a rubber O-ring with a big size of its cross-section.

Allowable values of maximal static and dynamic stuffing box radial displacements are calculated while a design developing of particular sealing device, in order to ensure a long-term reliable equipment operation.

Sealing device for centrifugal
vertical high capacity pump type of OPV-10-185

☑ has radially movable stuffing box self-aligning coaxially with a shaft with a diameter of 350mm and revolution rate of 290rpm;

☑ stuffing box can radially shift very easily due to its rolling on 50 thrust balls installed in a separator;

☑ high reliability of the seal is achieved by enabling the dynamic compensation of the radial oscillations of a rotating shaft (up to 1.5 mm on the radius) and the static self-centering (up to 3.5 mm on the radius);

☑ practical absence of abrasive wear of the pump bearings and shaft surface due to reducing leakage through the seal;

☑ made in fully split-type version (each part consists from two halves), that makes the installation or the disassembling of the device much easier and removing the motor of pump unit is not needed. The material used is corrosion-resistant steel grade of 321 H (AISI).

Self-centering gland seal
for high speed pump SE 5000-160

☑ includes a self-centering stuffing box that is tracking the radial displacement of the shaft with a diameter of 128mm and a speed of 3000rpm;

☑ the stuffing box easily moves radially thanks to the shear deformation of thrust rubber O-ring with a big cross-section diameter - 10mm;

☑ long lasting durable operation of the pump is provided by the compensation of dynamic (up to 0.2 mm on the side) and static radial displacements of the shaft (up to 1 mm on the side);

☑ made without the cooling system of seal housing, as operating temperature does not exceed 120°C;

☑ all parts are made of stainless steel type of 321 H (AISI).

Wellhead seal for polished rod of
oil pumping equipment

☑ consists of a immovable lower standby seal and a radially movable upper primary seal for polished rod with a diameter of 32mm;

☑ dynamic tracking radial oscillations of rod up to 2mm on the radius;

☑ due to working fluid pressure the upper primery seal is pressed to thrust balls and by rolling on them can easily be shifted radially after the rod;

☑ as a sealing material of the upper primary seal used braided packing;

☑ complete absence of leakage without the need for periodic tightening the gland packing;

☑ the gland packing is tightened automatically by a piston mounted in the upper seal thank to the pressure of the working medium;

☑ allowable working pressure is up to 40bar;

☑ it is allowed for the wellhead seal to operate at zero pressure of working medium;

☑ provides leaktightness even at strong fluctuations of the working medium pressure;

☑ made of carbon steel with zinc plating.

Floating stuffing box device
for sealing a shaft of a melting mixer

☑ used for an equipment that has a shaft with a length of 7.3m and with a diameter of 125mm and with a revolution rate of 30rpm;

☑ stuffing box leaned on the thrust balls and during the operation it begins to dynamically track the radial oscillation of the shaft within the scope of 2.5mm on the side;

☑ zero leakage with very rarely need in tightening the stuffing;

☑ operates in the working medium with abrasive and high viscosity properties;

☑ operates when there are shock loads on the shaft arising from the interaction of rotor blades and a stirred medium;

☑ the self-adjustable seal serves reliably even in case of significant shaft deflection caused of its great length;

☑ is produced in two versions: corrosion-resistant steel grade of 321 H (AISI) or carbon steel with double nickel-plated.

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