The gland device or gland packing is one of the types of sealing devices of movable joints of various devices and mechanisms. Due to the simplicity of its design, this is one of the most common and long-known sealing devices. The names of the stuffing box , stuffing box , stuffing box and others have been preserved since the time when grease soaked in grease was used in these devices, other materials are used in modern industry .
The gaskets are especially widely used in pipeline valves , where they are known as compaction of moving parts (assemblies) of valves with respect to the environment, in which a sealing element is used with the forced generation of stresses in it necessary to create the required tightness. [one]
Also, stuffing boxes operating on the same principle are widely used in various industrial, ship , automobile mechanisms. In addition to moving units, glands can be used to seal stationary equipment, for example in pipe and cable penetrations .
Content
Device and principle of operation
The essence of the stuffing box device is that on the outer side of the lid or body in the place where the stem or spindle passes through them, a stuffing box is created (sometimes it is called stuffing box [2] ), in which the packing material - stuffing box - is laid. Using special devices, the packing is pressed along the axis of the spindle (rod), abutting against the walls of the stuffing box and sealing the packing. When the packing is compressed, forces are created in it, under the influence of which it is pressed on one side to the wall of the stuffing box, and on the other hand, to the cylindrical surface of the spindle (rod). Thus, tightness is created and the working medium does not penetrate the equipment enclosure. In the mechanisms of small diameters, the packing is preloaded with a union nut , large - with a special part - an oil seal [3] - using hinged or anchor bolts with nuts (usually two) [4] .
Constructions
The friction force arising between the stuffing box and the stem prevents the latter from making the necessary movements, and with excessive tightening forces of the stuffing box make them impossible, therefore design and technological solutions that ensure their normal operation are of great importance, among them:
- stuffing material;
- stuffing box dimensions;
- construction of stuffing box components ;
- material of the rod (spindle), cleanliness of its surface treatment and others.
In some cases (among valves, as a rule, in control valves ), grease seals are used to reduce friction, which is supplied from the outside through a special grease fitting [4] ; in heavily loaded mechanisms, rod irrigation is used with water, for example, in mud pumps.
Materials
A modern stuffing box packing is usually a cord or rings made of asbestos with graphite impregnation. Fluorine-free or graphite-based asbestos-free sealing materials are also used. Instead of stuffing, rubber cuffs are sometimes used. Many other materials are also used, which is determined by the specific operating conditions [4] .
Notes
- ↑ GOST R 52720-2007. Pipe fittings. Terms and Definitions.
- ↑ English Stuffing box
- ↑ In technical jargon, this detail is often referred to as a groove book .
- ↑ 1 2 3 Usvatov-Usyskin R. F. Let's talk about reinforcement. - M .: Vitex, 2005.