What is Gland Packing

Gland Packing is also called sealing packing. It is usually braided from soft yarns. Usually square or rectangular or round strips with a cross-sectional area are filled in the sealing cavity.
Packing seals were first used to plug cotton, linen and other fibers into leakage channels to prevent liquid leakage. They were mainly used as shaft seals for water lifting machinery.

Due to the wide range of fillers, easy processing, low price, reliable sealing and simple operation, it is still used today. Nowadays, packing is widely used in the rotating shaft seals of centrifugal pumps, compressors, vacuum pumps, mixers and ship propellers, the reciprocating shaft seals of piston pumps, reciprocating compressors, refrigerators, and the rotating seals of various valve stems.

Braided packing is made of expanded graphite wires and is commonly used in most situations except strong oxidants. It can be used in boiling water, high temperature, high pressure steam, heat exchange media, oils, acids, alkali, hydrogen, ammonia, organic solvents, Hydrocarbons, cryogenic liquids and other media. It is a unique new type of sealing packing.

The principle is as follows:

Working Principle of Packing: The surface of the shaft is very uneven under microscopic conditions, and it can only partially fit with the packing. So there are tiny gaps between the packing and the shaft, like a maze. The medium is intercepted multiple times in the labyrinth to achieve a sealing effect.

The packing seal consists of packing packed in the stuffing box, and the packing is pressed against the surface of the shaft through the packing gland. Since the surface of the shaft is always somewhat rough, it can only partially fit with the filler, and some parts are not in contact, thus forming countless labyrinths. When the pressurized medium passes through the shaft surface, the medium is throttled multiple times, and sealing is achieved by virtue of this "maze effect".

The fit and friction between the packing and the shaft surface are similar to sliding bearings. There should be enough liquid for lubrication to ensure a certain life of the seal, which is the so-called "bearing effect". It can be seen that a good packing seal is a combination of the labyrinth effect and the bearing effect.

The pressing force of the packing on the shaft is generated by tightening the gland bolts. Since the packing is an elasto-plastic body, when it is compressed axially, friction force is generated, causing the pressing force to gradually decrease along the axial direction. At the same time, the radial pressing force generated makes the packing close to the shaft surface and prevents the medium from leaking out.

The distribution of the radial pressing force decreases sharply from the outer end (gland) to the inner end, and then becomes gentle. The distribution of the medium pressure gradually decreases from the inner end to the outer end. When the medium pressure at the outer end is zero, the leakage will be very small. Less, leakage when greater than zero.

With the continuous emergence of new materials, the structural types of fillers have also changed greatly, which will undoubtedly promote the wider application of packing seals. The materials used as fillers should have the following characteristics: have a certain elastic-plasticity. When the packing is pressed axially, it can generate a large radial pressing force to obtain a seal;

When the machine and shaft vibrate or the shaft has beating or eccentricity, it can have a certain compensation ability (following ability); chemical stability. It will neither be corroded or swollen by the medium, nor pollute the medium; it is impermeable.

The medium has some penetration into most fibers, so the filler structure is required to be dense. For this reason, when making fillers, it is often necessary to impregnate and fill various lubricants and fillers; it has good self-lubricating properties, small friction coefficient and wear resistance; temperature resistance . It can withstand a certain temperature when heated by friction; it is easy to disassemble; it is simple to manufacture and low in price.

SUNPASS SEALING TECH, founded in 1979, relies on more than 40 years of mature technology and experience, specializing in the production of packing and gaskets for industrial pump valves, has a high reputation and influence in the sealing industry at home and abroad. It has a modern professional factory building of 12000M2, and has more than 20 production lines for Gland Packing, such as: Graphite Packing, PTFE Packing, Aramid Packing, Acrylic Packing, Ramie Packing, etc. Products are widely used in petrochemical, oil and gas, electric power, smelting, mining, shipbuilding, paper making, food and machinery industries.
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Top-Sealing since1979, specializes in producing high quality Packing, including: Aramid Gland Packing、PTFE Gland Packing、Graphite Gland Packing、Carbon Gland Packing、Ramie Gland Packing、PTFE Gaskets, Graphite Gasket, Graphite Ring,Graphite Paper, Graphite Sheet, Graphite Tape, PTFE Sheet, Fiberglass Cloth, Fiberglass Tape, Fiberglass Rope, Ceramic Fiber Cloth, Ceramic Fiber Tape，Ceramic Fiber Rope

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