The sealing of fluids is essential for the proper functioning of mechanical equipment and the insertion of gaskets It is one of materials most used.
They are easy to install and suit virtually all types of fluids., be they of varying pressure and temperature ranges.
what are gaskets?
Gaskets are o-rings controlling that can be applied to static systems such as, for example, greenhouse doors and sealing of inspection and visit covers. But they can also be applied to dynamic systems., as a seal in valves, pumps and reactors.
Used 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 pressure. The specifications of each material used in its production determine the operating conditions for each product.
Simple features and mechanics, they contain a high degree of innovation in their materials used (fibers and lubricants), who must have resilience, adequate chemical and mechanical resistance.
How the gasket works
Gaskets work under compression. Mechanical or pressure packing consist of several rings that 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, but the amount of leakage considered normal depends directly on the type of gasket. However, The acceptable leak limit is 50 drops per minute.
The ones that don't leak are the compression gaskets used in valves with slow or infrequent movement., or static operations.
How to choose the most suitable gasket
When talking about gaskets, there are several configurations of braids, fibers and material combinations. 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 considered when finding the ideal gasket. a viscous mass is produced:
- Size: directly influences the type of gasket to be used. It is also important to know the diameter of the shaft where it will be applied.
- Temperature: directly influences the performance of gaskets. 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, know if it is gaseous or liquid, abrasive or clean, helps select the most suitable gasket material. Its attributes must have chemical compatibility with the fluid.
- Pressure: each gasket is also designed to withstand a certain pressure range. If it is applied to equipment with pressure greater than the supported limit, there can be serious accidents. Fluid pressure indication ensures good packing 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 that can be divided like this:
dynamic equipment → Can be subdivided into rotating equipment and reciprocating equipment:
- rotating equipment: pumps of the most varied types are part of this group. Gear pumps can be mentioned, centrifugal pumps, vacuum pumps, screw pumps etc.
- Alternative equipment: this group includes equipment such as piston pumps that can use gaskets as a form of sealing, depending on your size.
Static devices → In this group are the industrial valves that, despite having a rotating axis, have a very short and seasonal turn — i.e., the valve does not work constantly turning. There are several types of valves that have gaskets between their components., Examples include piston valves and control valves..
Types of gasket materials
The gaskets can be composed of different materials to meet the various possible applications.. dirt or breaks, check out some of the most used materials for its manufacture:
Acrylic: It has good mechanical resistance and provides excellent dimensional stability.. these gaskets are suitable for applications up to 230 °C water temperature adjustment.
ARAMID: It has excellent mechanical resistance and is capable of withstanding temperatures up to 280 °C water temperature adjustment. Made of dense and flexible material, this model is suitable for abrasive applications, tailings pump sets, piston pumps, refiners, between others.
Graphite / Carbon: are conformable materials with high thermal conductivity and chemical resistance. The combination of graphite and carbon makes the gaskets three times more resistant to extrusion compared to unreinforced graphite. Due to the great chemical resistance of the raw materials used, to 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: has high thermal stability, good chemical resistance and excellent lubricant retention, what makes these gaskets a recommended solution for use in applications with abrasive particles. They are used to seal abrasive fluids in steel industries, of cement, among others.
PTFE: It has excellent chemical resistance and low coefficient of friction.. Due to the characteristics of its main compound, the PTFE gaskets have as strengths their non-toxic attribute, excellent chemical resistance and sealability. Thus, they become an excellent option to act in the sealing of valve stems, chemical industry rotating equipment shafts, petrochemistry, pharmaceutical, cellulose andp paper, food and others.
Thermal Sealing: made of ceramic, these gaskets are indicated for thermal insulation at high temperatures. As this type of product has a high melting point, it is possible to achieve low thermal conduction and even low heat storage, allowing the equipment to work correctly at all times. These gaskets are indicated for applications that work at high temperatures., as a seal for oven and stove doors, thermal insulation of pipes, furnace and boiler inspection doors, in another word, where high-capacity thermal insulation is required.
GFO: is a high performance product aimed at industry in general where the purpose is to operate the equipment for a longer continuous time, in another word, with fewer interventions for adjustment or exchange. Its excellent continuity due to fibers and interweaving ensures operational economy by reducing friction., less leakage, maintenance and production process continuity. composed with 100% of GFO, these gaskets can be used for an extensive list of applications within the industry, like different bombs, including centrifuges, rotary, turbines and pistons. Also used in valves, agitators, mixers, dryers and refiners. Due to its wide range of services, they can be used as a standard gasket solution.
Learn more about sealing
Gaskets are just one of the materials used in sealing, but there are many others. Here in the Our site, you have access to the different types, application sites and also information about how to apply them in your industry and the sealing industry.
No Linkedin da KLINGER Brazil, it is possible to follow news of the segment, more information about products, tips on what type of material to use and other content under control, fluid monitoring and sealing.
