COMPRESSION PACKING: for the application of sealing materials?

For the proper functioning of mechanical equipment, fluid sealing is essential.. Various sealing solutions are used for this purpose., and the insertion of gaskets is the oldest method and also the most common nowadays.

Gaskets are sealing rings that can be applied in static systems such as greenhouse doors and sealing inspection and manhole covers.. Can also be applied to dynamic systems, such as valve sealing, pumps and reactors. Applied in systems with axial elements such as cylinders, pistons and shafts in general, the seal provided by the gaskets is given by the pressure that the material exerts against the wall of the axial element.

Gaskets seal for low, medium and high pressures. The characteristics of each material used in the production of the gasket, determines the operating conditions for each product. Simple features and mechanics, contain a high degree of innovation in their materials used (fibers and lubricants) must have resilience, adequate chemical and mechanical resistance.

Gaskets are easy to install and suitable for virtually all types of fluids, with different pressure and temperature ranges.

How the gasket works

The gasket works under compression. Mechanical or compression packing consists of several rings, which are inserted into the annular space (stuffing box) between the rotating or reciprocating member and the pump body or valve. When tightening the gasket press against the upper or outer ring, pressure is transmitted to the packing set, which expands the rings radially against the stuffing box side and seals.

Proper function of gaskets used in rotary or reciprocating pump service typically relies on a film of fluid to cool, lubricate and reduce friction, residual leakage is expected, The amount of leakage considered normal, directly depends on the type of gasket, still, one can generalize a leakage limit of 50 drops per minute as acceptable.

Compression gaskets used in valves with slow or infrequent movement or static operations do not leak.

How to select the most suitable gasket

Various braid configurations, fibers and material combinations are accessible when talking about gasket. Therefore, selecting the most suitable sealing material according to each application may not be such a simple process. There is, meantime, some attributes that must be informed in order to obtain an optimal packing selection. a viscous mass is produced:

• Size: the size of the stuffing box directly influences the type of gasket to be used. It is also important to know the diameter of the shaft where the gasket will be applied.;

• Temperature: the operating conditions of the medium directly influence the performance of the gasket, so knowing the temperature is essential. The higher the temperature, more meticulous must be the choice of gasket, since the wrong option can burn and char the material, which would make the gasket unable to perform the sealing function.

• Application: it is essential to know the type of equipment in which the gasket will operate to indicate the most suitable material;

• Fluid: the gaskets are built to operate in the most diverse types of fluids, meantime, as this is an element that indicates which type of gasket to use, know if the fluid is gaseous or liquid, abrasive or clean, help select the most suitable sealing material. The materials that make up the gasket must have chemical compatibility with the fluid.

• Pressure: in the same way, each gasket is designed to withstand a specific pressure range. If the gasket is applied to equipment with pressure greater than the supported limit, there can be serious accidents. Fluid pressure indication ensures good gasket performance.

• Speed: a good quality gasket is made of strong materials to ensure good operation also according to the shaft rotation speed.

Where gaskets are applied

Compression gaskets are used in mixers, agitators, dryers, valves, soot blowers, rotary pumps, centrifugal pumps, reciprocating pumps and many other types of mechanical equipment.

• dynamic equipment: It can be subdivided into rotating equipment and alternative equipment:
  • Rotating Equipment: Pumps of the most varied types are part of this group. Gear pumps can be mentioned, centrifugal pumps, vacuum pumps, helical pumps, etc.
  • Alternative Equipment: In this group there are equipment such as piston pumps that can use gaskets as a form of sealing depending on their size..

• Static devices: In this group are the industrial valves that, despite having a swivel axis, has a very short, seasonal turn, in another word, the valve does not work constantly turning, hence the classification as static. There are several types of valves that have gaskets between their components., we can cite by examples, piston valves and control valves.

Types of gasket wires

Gaskets can be made from different materials., to meet the various possible applications. dirt or breaks, some of the most used materials for the manufacture of gaskets:

• Acrylic: gaskets made from acrylic fiber yarns have good mechanical strength and provide excellent dimensional stability. It is suitable for applications up to 230ºC;
• ARAMID: Aramid gaskets have excellent mechanical strength and are able to withstand temperatures up to 280ºC. Made of dense and flexible material, this gasket model is suitable for abrasive applications, tailings pump sets, piston pumps, refiners, between others;
• Graphite / Carbon: Carbon and Graphite gaskets are conformable materials with high thermal conductivity and chemical resistance.. The combination of graphite and carbon makes it three times more extrusion resistant compared to unreinforced graphite gaskets. Due to the great chemical resistance of the raw materials used, Carbon Graphite Gasket can be used in virtually all media such as saturated or superheated steam, chemical products, gases, thermal fluids and solvents, with the exception of strong oxidizing agents, being widely used in boiler valves, hydrocarbons and in the petrochemical industry in general.
• phenolic: gaskets made of this material have high thermal stability, good chemical resistance and excellent lubricant retention, making this compression packing a recommended solution for use in applications with abrasive particles. It is used in applications with abrasive fluids in steel industries, of cement, among others.
• PTFE: PTFE gaskets have excellent chemical resistance and low coefficient of friction. Due to the characteristics of its main compound, PTFE gaskets have a strong point of non-toxicity, Excellent chemical resistance and sealability. Thus, PTFE gaskets become an excellent option for sealing valve stems, chemical industry rotating equipment shafts, petrochemistry, pharmaceutical, cellulose andp paper, food and others.
• Thermal Sealing: the gasket for thermal sealing is a product made of ceramic and is indicated for thermal insulation at high temperatures. As this type of product has a high melting point, it is possible to achieve a low thermal conductivity and still a low heat storage, allowing the equipment to work correctly at all times. It is suitable for applications that work at high temperature., sealing oven and greenhouse doors, thermal insulation of pipes, furnace and boiler inspection doors, in another word, where a product with high thermal insulation capacity is needed.
• GFO: The fiber compression packing is a high performance product focused for the industry at large where the purpose is to operate the equipment for a longer continuous time, in another word, with less interference to adjust or change the compression packing. Its excellent continuity in terms of fibers and interlacing ensure operational savings by reducing friction, less leakage, maintenance and production process continuity. composed with 100% of GFO, this gasket can be used for an extensive list of applications within the industry, like different bombs, including centrifuges, rotary, turbines and pistons. It is also used in valves., agitators, mixers, dryers and refiners. Due to its wide range of services, the GFO gasket can be used as a standard compression packing solution.