Stuffing box packing is the most common type of sealing materials used to fill the stuffing boxes of fittings, centrifugal and piston pumps, and various devices. More than 70% of pumps, 80% of fittings are completed with these packings. They differ both in the materials from which they are made, and in the methods of manufacture (structure). Both of these factors significantly affect the performance properties of packings.
According to the technical documentation, gland packing, GOST 5152-84 of which is enshrined in the relevant acts, is divided into asbestos-free (developed on the basis of bast and cotton fibers) and asbestos. GOST also fixes the limit values, sliding speeds, temperature, pressure, regulated for each brand of packings.
All packings containing asbestos are labeled with the letter "A". According to the type of packing, they are impregnated with a suspension of fluoroplastic, graphite-adhesive and fatty compositions, as well as dry (graphitized or clean). It is not surprising that in chemistry, energy, processing, gas and oil production, stuffing box graphite packing, produced on the basis of thermally expanded graphite, is actively used.
CLASSIFICATION, GRADES AND TECHNICAL CHARACTERISTICS OF PACKINGS
ASBESTOS DRY Gland Packings:
FILLING AS (asbestos braided dry packing)
Medium: Neutral liquid media, neutral and aggressive gaseous media,
gaseous and liquid ammonia, aggressive liquid media
Temperature range: -70 - +450С
Diameter: 4-36mm
ASBESTOS IMPREGNATED PACKINGS:
PACKING AP-31
Medium: Steam, neutral and aggressive liquid media, neutral and aggressive gaseous media, petroleum products
Temperature regime: -70 +300С
Diameter: 4-26mm
AGI PACKING (asbestos braided packing, glued with graphite (graphite), inhibited)
Working medium: Air, nitrogen, inert gases, water steam, petroleum products, water, feed water, organic products, liquid and gaseous ammonia, liquid and gaseous petroleum products and aggressive media
Temperature regime: -70 +600С
Diameter: 4-32mm
PACKING APR 31
Working environment: Neutral and aggressive liquid media, neutral and aggressive gaseous media, oil products
Temperature regime: -70 +300С
Diameter: 5-42mm
AFT PACKING (asbestos braided packing impregnated with a suspension of fluoroplast with talc)
Working environment: Liquefied gases, gaseous and liquid ammonia, sea water, organic products, ethylene, concentrated alkalis, alkali solutions
Temperature regime: -200 +300С
Diameter: 4-24mm
Gland packings, non-asbestos impregnated:
PACKING KhBP-31 (woven cotton packing, impregnated with a fatty antifriction composition based on petroleum extracts, graphite)
Medium: Air, inert gases, neutral steam, industrial water, hydrocarbons, fuel oils, mineral oils
Temperature range: -120C
Diameter: 4-35mm
PACKING LP-31
Medium: Air, inert gases, industrial water, sea water, alkali solutions, petroleum fuels, mineral oils
Temperature regime: +150C
Diameter: 6-38mm
Modern gland packing is, as a rule, a cord or rings made of asbestos impregnated with graphite. Asbestos-free sealing materials made of PTFE or graphite are also used. Rubber cuffs are sometimes used instead of padding. Many other materials are also used, which is determined by specific operating conditions.
Gland packing is the most popular type of seals not only for centrifugal pumps and fittings, but also for many other equipment.
This type of seal is a round or square cord impregnated with a material such as asbestos or graphite. Seals of centrifugal pumps are necessary in order to exclude, but rather reduce the leakage of fluid from the working chamber of the equipment.
Stuffing box seals, unlike mechanical seals, are not tight. To keep them in working order, it is necessary to ensure a minimum leakage for wetting.
Asbestos braided gland packings are used for sealing stuffing boxes of fittings, centrifugal and piston pumps, as well as various units at operating temperatures from -70 to +300˚С.
Braided stuffing box packings are the most common type of sealing materials used to fill the stuffing boxes of fittings, centrifugal and piston pumps, and various devices. More than 70% of pumps, 80% of fittings are completed with these packings. They differ both in the materials from which they are made, and in the methods of manufacture (structure). Both of these factors aresignificantly affect the performance properties of the packings.
Braided packings are based on various fibrous materials. In the ATI sub-sector, for the manufacture of braided packings, threads and yarns from asbestos, cotton, bast and chemical fibers are used.
An important component of packings are various types of impregnations and fillers, which give them the necessary properties.
Gland packing is a high-quality sealant, using which you can ensure reliable and durable sealing of joints. Stuffing box packing can be in the form of not only a cord (rectangular (including square) or round section), but also consist of one or more suitably molded rings. It is widely used when joining elements of such common devices and structures as:
pump;
autoclave;
pipeline system;
compressor, etc.
Omental packing is in demand in various sectors of the economy:
gas;
oil refining;
nuclear;
food, chemical and other types of industrial production;
in public utilities;
mining, gas and oil transportation.
Stuffing box packing: types and scope
Gland packing is very popular, as it provides a high level of tightness, reliable and durable connection. In addition, there is a huge variety of this type of seals. In the distribution network you can find the following types of stuffing box packing:
graphite;
asbestos;
bast or cotton;
with fat or fluoroplastic impregnation;
from brass reinforced wire.
In addition, there are the following types of gland packing:
single layer;
multilayer;
created using the technology of through weaving.
They provide a high level of tightness, while preventing penetration into the connection, a particular system, a specific unit - water, steam, gas, oil and oil products, emulsion and chemically aggressive liquids.
Graphite gland packings
The braided graphite thread under pressure of the stuffing box creates a homogeneous mass, and no leakage is observed. In this way, leakage is controlled with the least tightening pull, which allows for a longer gasket life. Graphite has a higher heat conductivity than traditional analogues, for example, from asbestos, due to which, in pump compartments sealed with this type of gland packing, heat is efficiently distributed over the entire area - the number of losses required for heat removal is zero.
Asbestos packings
This type of gland packing is used in aggressive environments, as it copes well with high temperatures and pressures. In the industry, for the manufacture of gland packings, threads and yarn from asbestos, cotton, bast and chemical fibers are used and are guided by the GOST 5152-84 standard. An important component of this type of packing are various types of impregnations and fillers that give them the necessary properties.
Fluoroplastic gland packings
An important segment of stuffing box packings are PTFE packings. Fluoroplast, also known as polytetrafluoroethylene (PTFE) or Teflon (trademark), was obtained just before the start of the Second World War, but on a really large scale it began to be used after it ended. Fluoroplastic (PTFE) is an effective stuffing box material. Its advantages: high resistance to the whole range of external chemical influences (the chemical inertness of fluoroplast is one of the highest in polymers), mechanical, thermal. An important advantage of fluoroplast is its low coefficient of friction, one of the smallest among materials used for sealing, therefore fluoroplast guarantees excellent rod (spindle) sliding. The consequence of all these properties is a long service life.
As an stuffing box packing, fluoroplast provides tightness when working with various working media: water, acids, oil, steam, gas, refrigerants. Due to the fact that this type of gland packing practically does not conduct heat, it can be used at high temperatures.
However, there are still some factors that limit the use of PTFE as a stuffing box material. It swells in liquid fluorocarbons at high temperatures, and upon contact with freons, even at room temperature, it slightly increases its volume. Not being wetted by water upon short-term immersion in it, the fluoroplastic is nevertheless wetted upon prolonged contact with distilled water, measured in tens of days.
Fluoroplastic gland packing can be made both from pure polytetrafluoroethylene and from fluoroplast with fillers, for example, graphite-filled. Saturation of fluoroplastic yarn with graphite with the formation of bonds between it and fluoroplast at the molecular level makes it possible to produce gland packings with unique, even more pronounced qualities than pure fluoroplast.
Fluoroplastic yarn canconsist of a thin twisted tape or a large number of twisted long thin fibers. In the second case, the gland packing is denser.
Scope: stuffings omental plumbing
The use of stuffing box packings in plumbing work is due to the presence in this area of many moving elements that need a tight, reliable and durable seal. These characteristics of stuffing box packings are used in the repair of shut-off valves of pipelines, both cold and hot. In particular, in conditions of hot water supply, when the temperature and pressure of the transported medium do not allow the use of various types of rubber or other seals, stuffing box packings of various brands and types come to the rescue.
The use of packings as a sealant for reinforcing joints is explained by the fact that its fibers are long, thin and at the same time strong, so the stuffing box is tightly packed into recesses and does not collapse when screwing on fittings or fittings. It also swells when wet, so small leaks on a new joint will usually go away on their own.
Stuffing box grades
They are divided into two main groups - asbestos and made of other material.
Advantages and benefits of gland packings
High level of chemical and radiation resistance.
Heat resistance and tightness.
Environmental friendliness.
Friction values close to zero.
Resistance to high and low temperatures, their sharp fluctuations.
High mechanical strength.
Not susceptibility to the effects of a variety of chemically aggressive substances.
chemical inertness.
Simplicity and ease of use. Cord-like packing is easy to wind
High level of sealing of joints and joints.
Having considered what stuffing box packing is, the types and scope of this consumable material, we can conclude that this is an indispensable element of various structures and devices that does not allow the possibility of leakage of working fluids and gases, providing reliable sealing.
There is a wide variety of stuffing box packings from which you can choose the one you need to ensure the tightness of a particular connection in a system in which certain gases and liquids are present. The properties of modern gland packings produced by our company ensure the reliability and durability of a particular device, structure or pipeline system.
You can buy Omental stuffing from us at the most favorable price in Ukraine. A wide range of products allows us to quickly and efficiently fulfill any order, helping to complete any construction work on time.
