The History of Valve

Valves are devices used to regulate fluid flow, pressure, and flow direction. Regulated fluid can be a liquid, a gas, a gas-liquid mixture, or a solid-liquid combination. The valves normally consist of the body, cover, valve seat, opening and closing components, driving mechanism, seals, and connectors. The control function of the valve is obtained by means of a driving mechanism or fluid that drives the lifting, sliding, swinging, or rotating movement of the opening and closing components to adjust the size of the runner section. The use of the valve is very broad, it has a close association with people’s everyday lives, for eg, the tap water pipe and the PRV used in the liquefied petroleum gas stove are valves. Valves are also critical components of a wide range of mechanical machinery, such as internal combustion engines, steam-driven engines, air compressors, pumps, pneumatic transmission systems, hydraulic transmission machines, ships, and aircraft.

Before 2,000 B.C.

Before 2,000 B.C., Chinese people use bamboo pipes and cork valves on the water piping system, then used sluice gates on irrigation canals, used plate-check valves on the smelter’s bellows, and collected brine with bamboo tube and plate type check valves in well salt mining, and emerged in Europe with the introduction of smelting technology and hydraulic machinery. Lead & copper cock valve. The safety valve of the lever was created in 1681 for the use of boilers. Plug valves and check valves were still the main valves until Watt’s steam engine arrived in the 18th century. The invention of a steam engine led valves to enter the mechanical industry. In addition to the use of plug valves, safety valves, and valves on the Watt steam engine, butterfly valves were often used to control the flow. Increased steam flow and pressure mean that the use of a stopcock to regulate the steam intake and exhaust steam of the steam engine will no longer satisfy the needs, such that the valve appears.

On and after 1840

On and after 1840, there were successive shut-off valves with threaded stem and wedge gate valves with trapezoidal threaded stem, a significant advancement in valve production. The introduction of these two types of valves not only satisfied the demands of different industries for increasing pressure and temperature at the point but also eventually fulfilled the requirements of the flow control. Ever since, with the growth of the electrical power industry, the petroleum industry, the chemical industry, and the shipbuilding industry, different forms of high and medium pressure valves have evolved rapidly.

Since WWII

Since WWII, the old cock valve and butterfly valve saw new applications due to the production of polymeric materials, stainless steel, lubricating materials, and cobalt-based cemented carbide. Ball valves and diaphragm valves evolved quickly. Globe valves, gate valves, and other valves have enhanced and improved efficiency. The Valve Manufacturing Industry has increasingly become an important field of the machine industry. The valves can be divided into six categories: valve used for cut-off, regulation, check valve, shut-off valve, safety valve, and multipurpose valve function.

The shut-off mechanism is primarily used to break the fluid flow, like a gate valve, a cock valve, a ball valve, a butterfly valve diaphragm valve, a pinch valve, and so on. The control valve is mainly used to adjust the pressure and velocity of the fluid, like the throttle valve, the pressure relief valve and the floating ball valve, etc. The check valve is used to keep the fluid flow from reversing; the diversion valve is used in the valve. Passage of a fluid or isolation of a two-phase fluid, including a sliding valve, a multi-pass valve, a drain valve, and an air drain valve; the safety valve is being used mainly for safety protection to keep the furnace, pressure vessel, or pipe from being broken by overpressure; the valve is a valve with more than one feature, such as a shut-down valve, which may both serve as an overpressure valve.

Industrial pipeline valves can be classified into a vacuum valve, a low-pressure valve, a medium-pressure valve, a high-pressure valve, and an ultra-high-pressure valve by nominal pressure, and the valve can be again divided into a standard temperature valve, a medium-temperature valve, a high-temperature valve and a low-temperature valve at operating temperature, and the valve can also be categorized by type that how its driven. Valves may be named individually or in combination according to different classification methods and may also be named according to the structural properties or particular uses of the opening and closing components.

The process requirements of the valve are working pressure, working temperature, and calibration. Nominal valves and nominal diameters are widely used as standard specifications for the separate valves used in industrial pipelines. Nominal pressure corresponds to the mean operating pressure of the substance valve at the specified temperature. Nominal diameter refers to the nominal interior diameter of the joining end of the valve body and the pipe.

Valves have different requirements depending on their form and usage, in particular, sealing, strength, control, circulation, opening, and closing. In the configuration and selection of valves, in addition to the specific parameters and properties, attention should be given to the efficiency of the fluid, including the phase state of the fluid (gas, liquid, or solid particles), corrosion, flammability, viscosity, toxicity, explosive, and radioactivity.

Sealing efficiency and strong performance are the most fundamental and critical characteristics of all valves. The valve is sealed in two parts: the internal seal and the outside seal. The internal seal is the seal between the valve and the valve seat; the outside seal is the seal in between the valve stem and the bonnet, the valve body, and the pipe joint. Valves not only need good sealing capacity, but they also ensure protection.

If the leakage of the seal is not successful and the strength is not adequate, the components will be destroyed, resulting in economic damages of varying degrees, such as the transport of hazardous material, flammable and explosives or heavy corrosive fluid, and can also cause severe safety incidents. In order to guarantee the seal and strength of the valve, in addition to the proper nature of the structure and the consistency of the operation, the material must be carefully chosen in compliance with the applicable requirements.

Generally, low-pressure non-corrosive fluid valves are made of cast iron or cast copper; high-to medium-pressure valves are made of cast steel or forged steel; high-temperature or high-pressure valves are made of alloy steel; corrosive fluid valves are made of stainless steel, plastic to corrosion-resistant alloys (such as copper-nickel-molybdenum alloys, lead alloys, and titanium alloys , etc.) or are made of cast iron.

Usually, low-pressure valves are often made of brass or copper, high-and medium-pressure valves are most often made of stainless steel, and high-and medium-pressure valves or high-temperature valves with higher specifications utilize cobalt-based cemented carbide. Polymer products have been extensively used in pipes. For eg, the seat of the ball valves is largely composed of polytetrafluoroethylene plastic and the sealing ring of the butterfly valves and the diaphragm of the diaphragm valves is made of different rubber materials. These materials have greater binding properties than metals in the temperature range that can be used.

With the advancement of modern nuclear, petrochemical, electronics, and aerospace industries, as well as the advancement of process automated control and long-distance transport of fluids, the development of modern cryogenic valves, vacuum valves, nuclear valves, and other control valves has been encouraged. The use of valve drive systems for remote control and program control is increased.

In the future, the production of valves will broaden the product specifications, introduce energy-saving, labour-saving, and self-control valves, upgrade systems, implement new technologies and methods, increase the service life of the valves, and introduce special series of valves, such as liquid oxygen, cryogenic valves, vacuum valves, nuclear valves, safety valves, valve regulators, traps and valve actuation devices for liquid hydrogen and liquefied natural gas.