Valve sealing surface, stem and stem nut material description valve localization is waiting for the valve company to take appropriate measures

Valve sealing surface, stem and stem nut material description valve localization is waiting for the valve company to take appropriate measures

The sealing surface is the key working face of the valve. The quality of the sealing surface is related to the service life of the valve. Usually, the sealing surface material should consider corrosion resistance, abrasion resistance, erosion resistance, oxidation resistance and other factors. The stem nut is directly subjected to the axial force of the stem during valve opening and closing and must therefore have a certain strength. At the same time, it is threaded with the stem, requiring a small coefficient of friction, no rust and avoid the phenomenon of biting. Stem NUTS WITH MELON CLUTCHES FOR USE ON ELECTRIC VALVES REQUIRE HEAT TREATMENT FOR HIGH HARDNESS OR SURFACE HARDNESS.
Sealing surface material
The sealing surface is the key working face of the valve. The quality of the sealing surface is related to the service life of the valve. Usually, the sealing surface material should consider corrosion resistance, abrasion resistance, erosion resistance, oxidation resistance and other factors.
There are usually two main categories:
(1) Soft material
1, rubber (including butadiene rubber, fluorine rubber, etc.)
2, plastic (PTFE, nylon, etc.)
(2) hard sealing materials
1, copper alloy (for low pressure valve)
2, chromium stainless steel (for ordinary high pressure valve)
3, Sitai alloy (for high temperature and high pressure valves and strong corrosion valves)
4. Nickel base alloy (for corrosive media)
Stem material
The stem is subjected to pulling, pressing and torsional forces during valve opening and closing, and is in direct contact with the medium while
There IS ALSO RELATIVE FRICTION MOVEMENT BETWEEN AND PACKING, SO THE STEM MATERIAL MUST HAVE SUFFICIENT STRENGTH AND IMPACT AT SPECIFIED TEMPERATURES
Toughness, corrosion resistance and abrasion resistance, and good technology.
Common stem materials are as follows.
First, carbon steel
When used in water and steam medium with low pressure and medium temperature not exceeding 300℃, A5 common carbon steel is generally selected.
For medium pressure and medium temperature does not exceed 450℃ water, steam medium, generally choose 35 quality carbon steel.
Two, alloy steel
For medium pressure and high pressure, medium temperature does not exceed 450℃ water, steam, oil and other media, generally choose 40Cr (chromium steel).
For high pressure, medium temperature does not exceed 540℃ water, steam and other media, can choose 38CrMo>
For high pressure, medium temperature does not exceed 570℃ steam medium, generally choose 25Cr2MoVA chromium molybdenum vanadium steel.
Three, stainless acid steel
For medium pressure and high pressure, medium temperature does not exceed 450℃ non-corrosive medium and weak corrosive medium, can choose 1Cr13, 2Cr13, 3Cr13 chromium stainless steel. For corrosive media, Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti and other stainless acid-resistant steel and PH15-7mO precipitation hardening steel can be selected.
Four, heat resistant steel
4Cr10Si2Mo Martensite type heat-resistant steel and steel can be used when the medium temperature is not more than 600℃
4Cr14Ni14W2Mo Austenitic type heat resistant steel.
Stem nut material
The stem nut is directly subjected to the axial force of the stem during valve opening and closing and must therefore have a certain strength. At the same time, it is threaded with the stem, requiring a small coefficient of friction, no rust and avoid the phenomenon of biting.
First, copper alloy
Copper alloy friction coefficient is small, no rust, is one of the commonly used materials. For PG1.6mpa low pressure valves ZHMN58-2-2 cast brass can be used. For PG16-6.4mpa medium pressure valve can use ZQ>
Second, the steel
When the working conditions do not allow the use of copper alloy, can choose 35, 40 quality carbon steel, 2Cr13, 1Cr18Ni9, Cr17Ni2 and other stainless acid-resistant steel.
Working conditions are not allowed to refer to the following.
1, for electric valve, valve stem nut with melon clutch, need to be heat treated to obtain high hardness or surface hardness.
2, the working medium or surrounding environment is not suitable for the selection of copper alloy, such as copper corrosion of ammonia medium. When selecting steel stem nuts, special attention should be paid to the phenomenon of thread bite.
The next few years will be the valve industry’s high-speed shock period, the direct consequence of this high-speed shock is the current trend of polarization in the valve cabinet brand camp to expand.
It is expected that in the next few years can really survive in the market valve enterprises are not so many.
But the valve industry this high-speed shock will bring great opportunities, shock results will make the market operation more rational.