Type of gasket
There are many ways to distinguish gaskets, usually by material categories can be divided into full metal (octagonal oval pad, etc.), semi-metal (winding gasket/corrugated pad, etc.), non-metal (CFS, etc.)
Gasket material
The choice of gasket material mainly depends on the following three factors: medium temperature and pressure
I. metal gasket materials
1. Carbon steel:
Recommended maximum working temperature does not exceed 538 ℃, especially when the medium with oxidizing.High quality carbon sheet steel is not suitable to be used in equipment for the manufacture of inorganic acids, neutral or acidic salt solutions. If carbon steel is subjected to severe stress, the equipment failure rate for hot water conditions is very high.Carbon steel gaskets are commonly used in high concentrations of acid and many alkaline solutions.Brinell hardness is about 120.
2. 304 stainless steel
18-8 (18-20%, nickel chromium 8-10%), the recommended maximum working temperature does not exceed 760 ℃.- 196 ~ 538 ℃ in the temperature range, prone to stress corrosion and intercrystalline corrosion.Brinell hardness 160.
3． 304 l stainless steel
The carbon content shall not exceed 0.03%.Recommended maximum working temperature does not exceed 760 ℃.Corrosion resistance similar to 304 stainless steel.The low carbon content reduced the precipitation of carbon from the crystal lattice, and the grain boundary corrosion resistance was higher than that of 304 stainless steel.Brinell hardness is about 140.
4． 316 stainless steel
18-12 (chromium 18%, nickel 12%), increase about 2% molybdenum in 304 stainless steel, when the temperature increases its strength and corrosion resistance.When the temperature increases, it has higher creep resistance than other ordinary stainless steel.Recommended maximum working temperature does not exceed 760 ℃.Brinell hardness is about 160.
5． 316 l stainless steel
Recommended maximum continuous working temperature does not exceed 760 ℃ ~ 815 ℃.Carbon content no more than 316 stainless steel in the superior stress and grain boundary corrosion.Brinell hardness is about 140.
6． 20 alloy
45% iron, 24% nickel, 20% chromium and a small amount of molybdenum and copper.Recommended maximum working temperature does not exceed 760 ℃ ~ 815 ℃.Especially suitable for the manufacture of sulfuric acid corrosion resistant equipment, brinell hardness about 160.
7． aluminum
Aluminum (no less than 99%).Aluminum has excellent corrosion resistance and processing properties, suitable for the manufacture of double - clamped gasket.Brinell hardness is about 35.Recommended maximum continuous working temperature does not exceed 426 ℃.
8． copper
The composition of red copper is close to that of pure copper.Recommended maximum continuous working temperature does not exceed 260 ℃.Brinell hardness is about 80.
9． brass
（Copper 66%, zinc 34%, in most working conditions, has good corrosion resistance, but not suitable for acetic acid, ammonia, salt and acetylene.Recommended maximum continuous working temperature does not exceed 260 ℃.Brinell hardness is about 58.
10．Hartz - 2 B
(26-30% molybdenum, 62% nickel and 4-6% iron).Recommended maximum working temperature does not exceed 1093 ℃.Excellent corrosion resistance to hydrochloric acid.It also has excellent resistance to wet hydrogen chloride gas corrosion, sulfuric acid, phosphoric acid and reducing salt solution corrosion.High strength at high temperature.Brinell hardness is about 230.
11．Hartz C - 276
Molybdenum (16-18%), chromium (13-17.5%), tungsten (3.7-5.3%), iron (4.5-7%), and nickel (the rest).Recommended maximum working temperature does not exceed 1093 ℃.Excellent corrosion resistance.It has excellent corrosion resistance to all kinds of tried cold nitric acid or boiling nitric acid with the concentration of 70%, good corrosion resistance to hydrochloric acid and sulfuric acid and excellent stress corrosion resistance.Brinell hardness is about 210.
12．Inconel 600
Nickel-based alloys (77% nickel, 15% chromium and 7% iron).Recommended maximum working temperature does not exceed 1093 ℃.High strength at high temperature, usually used to solve stress corrosion problems of equipment.At low temperature, with excellent processing performance.Brinell hardness is about 150.
13．Monel 400
(copper, nickel 30% recommended maximum continuous working temperature does not exceed 815 ℃.It has excellent corrosion resistance to most acids and bases except strong oxidizing acids.It is easy to produce stress corrosion crack in fluoric acid, mercury chloride and mercury medium.Equipment widely used in the manufacture of hydrofluoric acid.Brinell hardness is about 120.
14．titanium
Recommended maximum working temperature does not exceed 1093 ℃.Excellent corrosion resistance at high temperature.It is well known that it is resistant to chloride ion corrosion and has excellent resistance to nitric acid corrosion in a wide range of temperature and concentration.Titanium is rarely used in most alkali solutions and is suitable for oxidation conditions.Brinell hardness is about 216.
Ii. Non-metallic gasket materials
1． Natural rubber NR
Good corrosion resistance to weak acid and alkali, salt and chloride solution, poor corrosion resistance to oil and solvent, not recommended for ozone medium.Recommended operating temperature - 57 ℃ ~ 93 ℃.
2． Neoprene CR
Neoprene is a synthetic rubber that is resistant to moderately corrosive acid, alkali and salt solutions.Good corrosion resistance to commercial oils and fuels.But the corrosion resistance is poor in strong oxidizing acids, aromatic hydrocarbons and chlorinated hydrocarbons.Recommended operating temperature - 51 ℃ ~ 121 ℃.
4． Fluorine rubber
For oil, fuel, chloride solution, aromatics and fatty hydrocarbon and acid have good corrosion resistance, but not suitable for amine, lipid, ketone and steam, recommended operating temperature - 40 ℃ ~ 232 ℃.
5． Chlorosulfonated polyethylene synthetic rubber
It has good corrosion resistance to acid, alkali and salt solutions, and is not affected by climate, light, ozone, and commercial fuels (such as diesel and kerosene).But not suitable for aromatic hydrocarbons, chlorinated hydrocarbons, chromic acid and nitric acid.Recommended operating temperature - 45 ℃ ~ 135 ℃.
6． Silicone rubber
Good corrosion resistance to hot air.Silicone rubber is impervious to sunlight and ozone.But arf is used for steam, ketones, aromatic hydrocarbons and lipid hydrocarbons.
7． Ethylene propylene rubber
It has good corrosion resistance to strong acid, strong alkali, salt and chloride solution.Not suitable for oils, solvents, aromatics and hydrocarbons.Recommended operating temperature - 57 ℃ ~ 176.
8． graphite
The material does not contain resin or inorganic materials of all graphite materials, can be divided into doped metal or not doped metal element graphite materials.The material can be adhered to produce gaskets for pipes larger than 600MM in diameter.Excellent corrosion resistance to many acids, bases, salts and organic compounds and heat transfer solutions, even high temperature solutions.It doesn't melt, but more than 3316 ℃ when the sublimation.Caution should be exercised in the use of this material in highly oxidizing media at high temperatures.In addition to being used for gaskets, the material can also be used for making non-metallic winding strips in packing and winding gaskets.
9． Ceramic fiber
Forming on the strip of ceramic fiber is a kind of applicable to high temperature and low pressure condition and light flange gasket material, under the condition of excellent recommended working temperature 1093 ℃, wound gaskets can be made up of nonmetal winding belt.
10． teflon
The advantages of focused most of the plastic gasket materials, including heat resistance from - 95 ℃ ~ 232 ℃.In addition to free fluorine and alkali metals, it has excellent corrosion resistance to chemicals, solvents, hydroxides and acids.PTFE material can be filled with glass in order to reduce the cold flow and creep of PTFE.
Gasket material
The choice of gasket material mainly depends on the following three factors: medium temperature and pressure
I. metal gasket materials
1. Carbon steel:
Recommended maximum working temperature does not exceed 538 ℃, especially when the medium with oxidizing.High quality carbon sheet steel is not suitable to be used in equipment for the manufacture of inorganic acids, neutral or acidic salt solutions. If carbon steel is subjected to severe stress, the equipment failure rate for hot water conditions is very high.Carbon steel gaskets are commonly used in high concentrations of acid and many alkaline solutions.Brinell hardness is about 120.
2. 304 stainless steel
18-8 (18-20%, nickel chromium 8-10%), the recommended maximum working temperature does not exceed 760 ℃.- 196 ~ 538 ℃ in the temperature range, prone to stress corrosion and intercrystalline corrosion.Brinell hardness 160.
3． 304 l stainless steel
The carbon content shall not exceed 0.03%.Recommended maximum working temperature does not exceed 760 ℃.Corrosion resistance similar to 304 stainless steel.The low carbon content reduced the precipitation of carbon from the crystal lattice, and the grain boundary corrosion resistance was higher than that of 304 stainless steel.Brinell hardness is about 140.
4． 316 stainless steel
18-12 (chromium 18%, nickel 12%), increase about 2% molybdenum in 304 stainless steel, when the temperature increases its strength and corrosion resistance.When the temperature increases, it has higher creep resistance than other ordinary stainless steel.Recommended maximum working temperature does not exceed 760 ℃.Brinell hardness is about 160.
5． 316 l stainless steel
Recommended maximum continuous working temperature does not exceed 760 ℃ ~ 815 ℃.Carbon content no more than 316 stainless steel in the superior stress and grain boundary corrosion.Brinell hardness is about 140.
6． 20 alloy
45% iron, 24% nickel, 20% chromium and a small amount of molybdenum and copper.Recommended maximum working temperature does not exceed 760 ℃ ~ 815 ℃.Especially suitable for the manufacture of sulfuric acid corrosion resistant equipment, brinell hardness about 160.
7． aluminum
Aluminum (no less than 99%).Aluminum has excellent corrosion resistance and processing properties, suitable for the manufacture of double - clamped gasket.Brinell hardness is about 35.Recommended maximum continuous working temperature does not exceed 426 ℃.
8． copper
The composition of red copper is close to that of pure copper.Recommended maximum continuous working temperature does not exceed 260 ℃.Brinell hardness is about 80.
9． brass
（Copper 66%, zinc 34%, in most working conditions, has good corrosion resistance, but not suitable for acetic acid, ammonia, salt and acetylene.Recommended maximum continuous working temperature does not exceed 260 ℃.Brinell hardness is about 58.
10．Hartz - 2 B
(26-30% molybdenum, 62% nickel and 4-6% iron).Recommended maximum working temperature does not exceed 1093 ℃.Excellent corrosion resistance to hydrochloric acid.It also has excellent resistance to wet hydrogen chloride gas corrosion, sulfuric acid, phosphoric acid and reducing salt solution corrosion.High strength at high temperature.Brinell hardness is about 230.
11．Hartz C - 276
Molybdenum (16-18%), chromium (13-17.5%), tungsten (3.7-5.3%), iron (4.5-7%), and nickel (the rest).Recommended maximum working temperature does not exceed 1093 ℃.Excellent corrosion resistance.It has excellent corrosion resistance to all kinds of tried cold nitric acid or boiling nitric acid with the concentration of 70%, good corrosion resistance to hydrochloric acid and sulfuric acid and excellent stress corrosion resistance.Brinell hardness is about 210.
12．Inconel 600
Nickel-based alloys (77% nickel, 15% chromium and 7% iron).Recommended maximum working temperature does not exceed 1093 ℃.High strength at high temperature, usually used to solve stress corrosion problems of equipment.At low temperature, with excellent processing performance.Brinell hardness is about 150.
13．Monel 400
(copper, nickel 30% recommended maximum continuous working temperature does not exceed 815 ℃.It has excellent corrosion resistance to most acids and bases except strong oxidizing acids.It is easy to produce stress corrosion crack in fluoric acid, mercury chloride and mercury medium.Equipment widely used in the manufacture of hydrofluoric acid.Brinell hardness is about 120.
14．titanium
Recommended maximum working temperature does not exceed 1093 ℃.Excellent corrosion resistance at high temperature.It is well known that it is resistant to chloride ion corrosion and has excellent resistance to nitric acid corrosion in a wide range of temperature and concentration.Titanium is rarely used in most alkali solutions and is suitable for oxidation conditions.Brinell hardness is about 216.
Ii. Non-metallic gasket materials
1． Natural rubber NR
Good corrosion resistance to weak acid and alkali, salt and chloride solution, poor corrosion resistance to oil and solvent, not recommended for ozone medium.Recommended operating temperature - 57 ℃ ~ 93 ℃.
2． Neoprene CR
Neoprene is a synthetic rubber that is resistant to moderately corrosive acid, alkali and salt solutions.Good corrosion resistance to commercial oils and fuels.But the corrosion resistance is poor in strong oxidizing acids, aromatic hydrocarbons and chlorinated hydrocarbons.Recommended operating temperature - 51 ℃ ~ 121 ℃.
4． Fluorine rubber
For oil, fuel, chloride solution, aromatics and fatty hydrocarbon and acid have good corrosion resistance, but not suitable for amine, lipid, ketone and steam, recommended operating temperature - 40 ℃ ~ 232 ℃.
5． Chlorosulfonated polyethylene synthetic rubber
It has good corrosion resistance to acid, alkali and salt solutions, and is not affected by climate, light, ozone, and commercial fuels (such as diesel and kerosene).But not suitable for aromatic hydrocarbons, chlorinated hydrocarbons, chromic acid and nitric acid.Recommended operating temperature - 45 ℃ ~ 135 ℃.
6． Silicone rubber
Good corrosion resistance to hot air.Silicone rubber is impervious to sunlight and ozone.But arf is used for steam, ketones, aromatic hydrocarbons and lipid hydrocarbons.
7． Ethylene propylene rubber
It has good corrosion resistance to strong acid, strong alkali, salt and chloride solution.Not suitable for oils, solvents, aromatics and hydrocarbons.Recommended operating temperature - 57 ℃ ~ 176.
8． graphite
The material does not contain resin or inorganic materials of all graphite materials, can be divided into doped metal or not doped metal element graphite materials.The material can be adhered to produce gaskets for pipes larger than 600MM in diameter.Excellent corrosion resistance to many acids, bases, salts and organic compounds and heat transfer solutions, even high temperature solutions.It doesn't melt, but more than 3316 ℃ when the sublimation.Caution should be exercised in the use of this material in highly oxidizing media at high temperatures.In addition to being used for gaskets, the material can also be used for making non-metallic winding strips in packing and winding gaskets.
9． Ceramic fiber
Forming on the strip of ceramic fiber is a kind of applicable to high temperature and low pressure condition and light flange gasket material, under the condition of excellent recommended working temperature 1093 ℃, wound gaskets can be made up of nonmetal winding belt.
10． teflon
The advantages of focused most of the plastic gasket materials, including heat resistance from - 95 ℃ ~ 232 ℃.In addition to free fluorine and alkali metals, it has excellent corrosion resistance to chemicals, solvents, hydroxides and acids.PTFE material can be filled with glass in order to reduce the cold flow and creep of PTFE.
