Material and process of pneumatic valve stem

pneumatic valve stem process
pneumatic valve rod in the process of pneumatic valve opening and closing, pull, pressure and under torsional force, and direct contact with the media, and packing friction and relative movement between at the same time, so when choosing pneumatic valve stem material, must ensure that its under the specified temperature of sufficient strength, good impact toughness, abrasion resistance and corrosion resistance. '
pneumatic valve stem and ball joints and pneumatic valve stem and valve body contact should be an antistatic mechanism, prevent electrostatic agglomeration on the sphere. Pneumatic valve stem safety design should prevent was 'blown out' under the working pressure, pneumatic valve stem blow-out proof flange of the disposal of a circular ring, in order to reduce friction coefficient.
traditional pneumatic valve stem
the characteristics of the machining process. Traditional pneumatic valve stem thread USES the spiral, precision is inaccurate; And the traditional vulnerability without crumbs screw rolling rolling dies, easy deformation, distortion.
. Polished rod parts adopt grinding machine precision is not high, time consuming,
. Pour off parts adopt two clamping turn end seal, concentricity, pour sealing leakage easily.
. End parts adopt milling machine dial indexing, processing, slow process, takes a long time.
the characteristics of the new type of pneumatic valve rod manufacturing process:
. New type of pneumatic valve rod thread with homemade extrusion, high intensity, precision.
. Threaded parts and parts of the polished rod of concentric, overcome the long plagued domestic thread rolling process easy distortion, vulnerability thread rolling die.
. Precision of the polished rod parts mirror effect, easy opening and closing, good seal.
. Pour off parts adopt numerical control technology a molding, high precision, pour sealing performance is good.
. Side parts forging forming technology on T slot, high efficiency and low cost.
. A complete set of pneumatic valve rod production technology reached the international advanced level.
in strong corrosion, volatile and toxic harmful process conditions, once the pneumatic valve stem seal is broken, strong corrosion, volatile and toxic and harmful medium leakage from the pneumatic valve pneumatic control valve stem, to the serious consequences of surrounding environment and personal safety. The corrugated pipe pneumatic stem seal form is a way to solve the above problem. Generally speaking, stainless steel bellows. The special structure of pneumatic valve cover protection control pneumatic valve packing to avoid contact with fluid, once the corrugated pipe burst, stuffing box at the top of corrugated pipe structure can prevent corrugated pipe rupture failure which is caused by serious consequences. In engineering practice, the choice of the form of bellows seal should fully consider bellows sealed pressure rating would reduce with the temperature increases, the fluid solid particles cannot exist, and the longest of the corrugated pipe material circulation life, etc. In some process of medium corrosion resistance of stainless steel is strong corrosion, medium such as process of wet chlorine, wet chlorine contained traces of hydrochloric acid can be made of stainless steel bellows was quickly corrosion.
pneumatic valve stem commonly used material is generally selected

copper alloy material grades have QA - ,HPb - - 。 Applicable to the nominal pressure is less than or equal to. MPa, temperature less than or equal to the degree of low pressure pneumatic valves.
carbon steel
is generally selected carbon steel A, steel, after nitriding process, applicable to the nominal pressure is less than or equal to. MPa of ammonia valve, water, steam and other medium of low and medium pressure pneumatic valve. A steel is suitable for the temperature does not exceed the degree of pneumatic valves; Steel is suitable for the temperature does not exceed the degree. ( Note: the real route that pneumatic valve rod manufactured carbon steel nitriding can't very well solve the problem of corrosion resistance, should avoid to use. Is generally selected

alloy steel material such as Cr, CrMoAA, CrMoVA. Cr after chrome plating processing, suitable for less than MPa nominal pressure, temperature less than or equal to the media such as water, steam, oil. CrMoAA through nitriding processing, can under the condition of the working temperature of MPa pressure, pneumatic valve commonly used in power station. CrMoVA after nitriding can handle under the condition of the working temperature of MPa pressure, pneumatic valve commonly used in power station.

stainless steel generally choose Cr, Cr, CrNi, CrNiMoTi etc. Cr, Cr stainless steel is suitable for the nominal pressure is less than or equal to MPa, temperature less than or equal to the degree of water, steam and weak corrosive medium, can through the chrome plating, high frequency quenching methods such as strengthening surface. CrNi stainless steel pneumatic valve, pneumatic valve, low temperature ability corrosive medium. CrNiTi, CrNiMoTi stainless acid-resistant steel used in the nominal pressure is less than or equal to. MPa, temperature less than or equal to degree high temperature pneumatic valve, can also be used for temperature less than or equal to - Stainless steel of the pneumatic valve, pneumatic valve at low temperature. CrNiTi ability nitric acid and other corrosive medium; CrNiMoTi ability of acetic acid and other corrosive medium. CrNiTi, CrNiMoTi used in pneumatic valve, high temperature nitriding process can be used, in order to improve abrasion resistance.
chrome steel bearings
choose GCr, applicable to the nominal pressure is less than or equal to the MPa and the degree of temperature less than or equal to superpressure pneumatic valves.
used in pneumatic valve rod material is more, there are CrSiMo martensite heat-resistant steel, CrNiWMo austenitic heat resistant steel, etc.