How to choose a gasket? Use sealing gasket properly

How to choose and use sealing gaskets reasonably

Medium, temperature, pressure and working conditions should be important factors. For example, when the working pressure is not high, use plastic flange butt (PN. Another example, in the working environment of chemical media, you must reasonably match different sealing media to achieve good results, otherwise unpredictable chemical changes are prone to occur. So any paradox in the choice of seals will lead to unimaginable consequences.

The general gasket structure has the following types for reference:
1. Used for flange connection a. Flat gasket: multi-purpose medium-pressure asbestos, oil-resistant asbestos, PTFE, graphite gasket or reinforced graphite gasket, Pad non-asbestos gasket, metal flat gasket, special metal Gaskets, etc.
b. Spiral wound gasket: with outer ring or with inner and outer ring (multi-purpose flat flat flange); with inner ring (concave and convex flange is commonly used); basic type (without inner and outer ring), special for fluted flange The sealing surface is narrow, and the flat welded full-plane flange has a wider sealing surface, which is equivalent to a wound gasket with inner and outer rings. Attention must be paid to which country and standard the flange is.
2. A variety of packings for rotating and pulling the shaft seal. Such as flexible graphite ring (open and non-open), braided packing (or packing ring) of various materials, internal and external skeleton oil seal YX ring and O ring of various materials.
3. Sealing products for special parts. Common sealing strips, PTFE ball valve seats, graphite packing rings and rubber butterfly valve rings, etc.

What should be paid attention to when installing seals?
1. Do not damage the sealing surface of the seal or the sealing line. The sealing performance of the flat seal depends on the upper and lower end faces; the sealing performance of the hydraulic seal depends on the lip line associated with the hole or shaft. These parts are both soft and rich. The resilient, temperature-resistant, corrosion-resistant, and aging-resistant graphite, rubber, and fiber are easily damaged special materials. Therefore, special protection and care are required during handling, installation, and storage. Once damaged, they will often be damaged. Leave a lot of hidden dangers to the sealed parts;
2. Do not force installation
Some seals are placed in a grooved stuffing box, which needs to be tightly installed. It must not be rough and brutal during construction. Forcible loading with large movements will inevitably destroy the original prefabricated structure of the seal. After filling in the required parts will inevitably lead to disaster. The installation of such seals must be very careful and careful, and embedding must be done step by step;
3. Pay attention to balance and symmetry during installation
Place the seal in a position that is close to the effective sealing surface (or lip line). After the system is opened and used, further observation and tightening of seals must be done to prevent the breakdown caused by micro-leakage due to changes in working conditions (such as pressurization) during system operation.

How to properly keep seals that are not in use temporarily?
1. Anti-aging, light-proof, moisture-proof, place flat, away from cold and heat sources;
2. Do not apply pressure to keep the seals in a natural relaxed state, without applying external force to change their physical shape;
3. Classification and marking of the same appearance, different materials, use parts, applicable standards, purchase date, etc.

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