Common Washer Performance - and new materials and new technologies

A common) Washer performance

When using the valve, often depending on the circumstances, the replacement of the original washer. Washers often are: rubber washer, rubber O ring, plastic flat washers, PTFE gasket package, asbestos rubber gasket, metal flat washers, metal shaped washers, metal foreskin washers, wave washers, washers and other entangled.

(1) rubber washers: deformed easily, effortlessly when pressed, but the pressure, temperature and capacity of poor, only for low pressure and high temperature. Natural rubber has certain corrosion resistance, temperature should not exceed 60 DEG C; chloroprene rubber can also use some acid, the temperature of 80 DEG C; nitrile rubber oil resistant, can be used to 80 DEG C; fluorine rubber, good corrosion resistance, heat resistance is better than the general rubber, can be used in 150 C medium.

(2) O - rubber gasket: cross sectional shape is a circle, there is a certain self tightening effect, seal better than flat washers, pressing force smaller.

(3) plastic flat washer: plastic is the biggest characteristic of good corrosion resistance, good heat resistance most plastics. PTFE plastic crown, has excellent corrosion resistance, and high temperature range is wide, can be used for a long time in the -180 to +200 DEG C.

(4) PTFE gasket package: in order to give full play to the advantages of PTFE, while addressing the shortcomings of its less flexible, made of rubber or Teflon coated asbestos rubber gasket. In this way, both PTFE flat gasket with the same corrosion resistance, and good flexibility, enhance sealing effect, reducing the clamping force. The cross-sectional shape as shown in figure 4-20.

(5) asbestos rubber gasket: asbestos rubber sheet cut. Its composition is 60 ~ 80% and 10 ~ 20% asbestos rubber, and fillers, curing agents. It has good heat resistance, cold resistance, chemical stability, and the supply of abundant and cheap. When in use, the clamping force not great. Because it adhesion of metal, so the best coated with a layer of graphite, in order to avoid demolition strenuous.

Asbestos rubber sheet in four colors: gray, (for the low grade XB-200, the pressure is less than or equal to 16 kg / cm2, the temperature of 200 DEG C); red, for medium (grade XB-350, pressure up to 40 kg / cm2, the temperature of 350 DEG C); purple red, for high (grades XB-450, pressure of 100 kg the temperature of 450 DEG C / cm2); green, used for oil pressure, performance is also very good.

(6) metal flat heat circle: lead, the temperature of 100 DEG C; aluminum copper 430 DEG C; 315 C 550 C; low carbon steel; nickel silver 650 DEG C; 810 DEG C; Monel alloy (nickel and copper) 810 C, 870 C stainless steel. Less able to lead one of voltage, aluminum can be resistant to 64 kilograms / square centimeter, and other materials can be high.

(7) specific metal gasket: lens gasket: a self energizing effect, used in high pressure valve.

Oval washer: pressure from the washers are.

Double cone washer: for high-pressure self seal.

In addition, there is a square, diamond, triangular, toothed, dovetail shaped, B shaped, C shaped, generally only used in high pressure valves.

(8) metal foreskin washers: metal pressure both good temperature performance and good flexibility. Wrapping material of aluminum, copper, low carbon steel, stainless steel, Monel alloy. Inside the filler material of asbestos, PTFE, glass fiber etc..

(9) wave washer: a pressing force is small, and good sealing effect. Often combined with metal and non-metallic form.

(10): wound gasket is the thin metal band and metal band close together, wound into a multi round, wave shaped cross section, have a good flexibility and sealing. The metal belt can be 0Cr13, 1Cr13, 08 steel, 2Cr13, 1Cr18Ni9Ti, copper, aluminum, titanium alloy, Meng Naier etc.. Non metallic materials with asbestos, PTFE etc..

More about the performance of sealing gaskets, enumerates some digital. It must be said that these figures with the flange form, medium repair and installation technology are closely related, sometimes more than, and sometimes fail, and the pressure and temperature performance, is also interchangeable, such as high temperature, pressure capacity is often reduced, these fine points, can only experience in practice.

Two) new materials and new technology

This gasket is still not complete, and the sealing technology is in rapid development. The following several examples of new materials and new technology.

(1) liquid seal: with the rapid development of organic synthesis industry, a liquid sealant, used in static sealing; this new technology, often called the liquid seal. The principle is the use of liquid seal, liquid sealant adhesion, mobility and monolayer effect (the thin film is the greater tendency of the natural recovery), where appropriate under pressure, it works the same way as the washer. So the use of a sealant, also known as liquid gasket.

(2) PTFE seal: PTFE is also a polymer compound, before it is sintered into a product called the raw material, soft texture, but also monolayer effect. With a band called the raw materials made of raw materials, can be rolled into long-term storage site. Use freely forming any joint, as long as a pressure, will form a uniform film plays a role in sealing ring. As the valve body and valve cover gasket, can not remove the valve or gate case, forced open a gap, into the raw material has been brought on line. Clamping force is small, not sticky, but also non stick flange, the replacement is very convenient. The most suitable for the tongue and groove flange. PTFE raw materials can also be made of tube and rod used for sealing.

(3) hollow metal O O-ring: good elasticity, clamping force is small, there is self energizing effect, can choose a variety of metal materials, can adapt to low temperature, high temperature and strong corrosion medium to.

(4) graphite plate ring: in people's minds, graphite is a brittle material, lack of flexibility and toughness, but after special treatment of graphite, is soft and good elasticity. In this way, graphite heat resistance and chemical stability, they can be displayed in the gasket material; and this washer clamping force is small, a very favorable sealing effect. This also made with graphite, with the metal band with the form of wound gasket performance. Graphite sheet seal and graphite spiral wound gaskets ---- the emergence of high temperature anti-corrosion sealing a major breakthrough. This type of washer, has a large number of overseas production and use.