Applications of Eight Different Gaskets
1. Spiral Wound Gaskets
Spiral wound gaskets skillfully take advantage of heat resistance, elastic resilience and strength of metal as well as flexibility of nonmetal materials. Therefore, spiral wound gaskets have good sealing performance, and stainless steel flexible graphite spiral wound gaskets have the best performance. Preload pressure of spiral wound gaskets is lower than asbestos spiral wound gaskets’. Therefore, spiral wound gaskets don’t have shortcomings of leakages. In the medium of oil, the metal strip is made of 0Cr13, and it is recommended that other media should be made of 1Cr18Ni9Ti.
Working pressure of stainless steel flexible graphite spiral wound gaskets is 14.7MPa (up to 19.6MPa in China) in the medium of gas, and 30MPa in the medium of liquid. Working temperatures of stainless steel flexible graphite spiral wound gaskets are from -190 to +600℃. Stainless steel flexible graphite spiral wound gaskets can be used at a temperature of 1000℃ under the situation of no oxygen and low pressure.
PTFE has good low temperature resistance, and its yield strength at low temperature is much higher than its yield strength at room temperature. Therefore, PTFE spiral wound gaskets can be used for the medium of low temperature such as liquid hydrocarbons. At the same time, operating temperature of PTFE spiral wound gaskets can reach at a temperature of 250 ℃ and 200℃ in acid media, because metal strips which are added to PTFE spiral wound gaskets improve thermal conductivity.
Spiral wound gaskets are suitable for heat exchangers, reactors, pipes and valves which have great fluctuations in pressure and temperature. When the pressure is over medium or the temperature exceeds 300 ℃, spiral wound gaskets with inner rings, outer rings or inner and out rings should be consider using. Male and female flanges with inner rings spiral wound gaskets can have the better effect.
Covering flexible graphite plates on both sides of flexible graphite spiral wound gaskets can also achieve the good sealing effect. A gastube boiler of a large-scale fertilizer plant which belongs to key equipment of high temperature and pressure equips with flexible graphite spiral wound gaskets with outer rings. When full loaded, the gastube boiler doesn’t leak; when unloaded, the gastube boiler leaks.
2. Flat Metallic Gaskets and Corrugated Metal Gaskets
Generally, flat metallic gaskets and corrugated metal gaskets are applied to valves with medium and high pressure and pipes and equipment flanges with small diameters. Working pressure of flat metallic gaskets and corrugated metal gaskets is based on different temperatures. Working pressure of flat metallic gaskets is from 1.568 to 31.36MPa, and working pressure of corrugated metal gaskets is from 1.568 to 3.92MPa. Materials of flat metallic gaskets and corrugated metal gaskets are selected according to the media and temperatures.
3. Octagonal Gaskets and Oval Gaskets
Octagonal gaskets and oval gaskets which are used for trapezoidal groove face flanges have good sealing performance. On the taper surface of grooves, octagonal gaskets are in direct contact with the taper surface, while oval gaskets are in line contact with the taper surface. Therefore, oval gaskets can fit the tape surface very well under the small fastening force, but there should be the second fastening; while octagonal gaskets usually don’t leak easily after one time fastening.
Source: China Gaskets Manufacturer – Yaang Pipe Industry (www.ugsteelmill.com)