Classification of valve pressure levels
Valve classification by pressure:
Vacuum valve—a valve with a working pressure below standard atmospheric pressure.
Low pressure valve—a valve with a nominal pressure PN less than 1.6MPa.
Medium pressure valve—A valve with a nominal pressure of PN 2.5 ~ 6.4MPa.
High pressure valve—a valve with a nominal pressure of PN10.0 ~ 80.0MPa.
Ultra-high pressure valve-a valve with a nominal pressure PN greater than 100MPa.
Pressure level Class and nominal pressure comparison table
The valve is a control component in the fluid delivery system, and has functions such as cut-off, regulation, diversion, prevention of back flow, voltage stabilization, shunting, or pressure relief.
Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oils, liquid metals and radioactive media.
Valves are also divided into cast iron valves, cast steel valves, stainless steel valves, chrome molybdenum steel valves, chrome molybdenum vanadium steel valves, dual-phase steel valves, plastic valves, and non-standard customized valve materials.
What is the differences between the brass ball valve and stainless steel ball valve ?
1. Different applicable substances
Stainless steel ball valve can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, muds, oils, liquid metals and radioactive media; copper ball valves are suitable for general working media such as water, solvents, acids and natural gas And, it is also suitable for media with harsh working conditions, such as oxygen, hydrogen peroxide, methane and ethylene.
2.Different media temperatures
In terms of medium temperature, under the same pressure environment conditions, the medium temperature range of copper ball valve is higher than that of stainless steel ball valve. If the medium temperature exceeds 80 ℃, copper ball valve must be used, but if it does not exceed 80 ℃, stainless steel ball valve can.
3.Different corrosion resistance
Copper ball valve has excellent corrosion resistance, switch operation is smooth and labor-saving, and durable. Stainless steel does not cause corrosion, pitting, rust or wear, and is resistant to high temperatures.
4. The working principle is different.
Copper ball valve: The ball valve is mainly used to cut off or connect the medium in the pipeline, and it can also be used for the regulation and control of the fluid. The hard-sealed V-type ball valve has a V-shaped core between the V-shaped core and the metal seat of the hard alloy Very strong shearing force, especially suitable for media containing fibers and small solid particles.
Stainless steel ball valve: The working principle of the ball valve is to open or close the valve by rotating the spool. The ball valve switch is lightweight, small in size, can be made into a large caliber, reliable sealing, simple structure, easy maintenance, the sealing surface and the spherical surface are often closed, and it is not easy to be eroded by the medium.
5. Different materials.
Copper ball valve: The material used is mainly composed of copper.
Stainless steel ball valve: The material used is mainly composed of stainless steel.
6, the price is different
Copper ball valve: costly materials are more expensive.
Stainless steel ball valve: cheaper material than copper ball valve.
Differences Between Silica sol investment casting and water glass investment castings
Silica sol and water glass are two kinds of different processes of investment castings. The cost of water glass is lower but it mainly suits for most carbon steel material products,and for the ones which is simple structure. Because if structure is complicated if by water glass then need too much later machine handle, that way increase cost instead.
Different adhesives are used, one is water glass and the other is silica sol. The shell mold is not the same for drying and hardening. Water glass uses a hardening agent such as ammonium chloride, while the silica sol shell mold is dried and hardened in a constant temperature and humidity space.
In addition to the surface smoothness and accuracy, the silica sol molding process is higher than water glass.
How many sets molds does it need for manufacturing one model stainless steel castings?
Normally one set is enough, according to dimension of castings, the artificial wax casting machine can make 1 or 2 or 4 pieces wax castings at one time. The automatic wax casting machine can come out 8-9 pieces wax castings at one time, it is faster, meanwhile its cost is a little higher.
Normally one wax casting machine make one products.
In our location,manufacturer of stainless steel ball valve are mainly located in Cang County or Haixing County of Cangzhou City, Hebei Province, China。
If want to buy stainless steel ball valve lower, customers would better buy it from China markets, and from Manufacturing factory.There are many manufacturers of stainless steel valves. They are cheap to go to Wenzhou city to buy, and the quality is good to buy in Jiangsu and Hebei province.
The premise is to see what kind of occasions you use, materials, seals, leak levels, etc. should be considered comprehensively, according to the use of the right valve.
The general ball valve does not indicate the direction and can be installed casually. It is reasonable to say that the ball valve has no direction, but in actual installation, in order to prevent excessive leakage between the valve body and the valve cover, the ball valve body is generally connected to the direction of the tank or material. Some ball valves are directional, generally there are marks of direction on the ball valve, if it was installed conversely, then will achieve a bad seal results. The ball valve is divided into a one-way sealing ball valve and a two-way sealing ball valve. The former has directionality. If the installation is reversed, the sealing under the complete pressure difference cannot be guaranteed, and the latter has no directivity. If the manual ball valve is not oriented, but if it is also control valve, it is directional. V-type ball valves and eccentric hemisphere valves are directional, and generally the medium flow direction mark is marked on the valve body. The floating ball valve and the fixed ball valve are two-way, and the eccentric hemispherical valve, the V-shaped ball valve, and the poppet-type track ball valve are unidirectional. The ball valve has an O-ball valve and a V-ball valve.
Ball valve (the ball valve should be a stop valve in the oceaneering andship domain fields), refers to a kind of valve which open or close by turning the ball with a hole on it. The standard GB/T21465-2008 "Valve Terminology" is defined as: the opening and closing member (sphere) is driven by the valve stem and rotates around the square ball valve as the axis for rotary motion. It can also be used for the adjustment and control of fluids. The hard-sealed V-ball valve has a strong shear force between the V-shaped core and the metal seat of the hard facing alloy. It is especially suitable for fiber-containing, tiny solid particles medium. The multi-way ball valve not only can flexibly control the switching of the merge, split, and flow directions of the medium, but also can close any channel and connect the other two channels. This type of valve should generally be installed horizontally in the pipeline. Ball valve classification: pneumatic ball valve, electric ball valve, manual ball valve.
1.1 Preparation before installation
(1) The pipeline before and after the ball valve is ready. The front and rear pipes should be coaxial and the two flange sealing surfaces should be parallel. The pipe should be able to withstand the weight of the ball valve, otherwise the pipe must be equipped with appropriate support.
(2) Purge the front and rear lines of the valve to remove oil, welding slag and all other impurities from the pipe.
(3) Check the sign of the ball valve and find out that if the ball valve is intact. The valve was fully opened and closed several times to confirm that it was working properly.
(4) Remove the protective parts on the connecting flanges at both ends of the ball valve.
(5) Check the valve hole to remove any dirt that may be present, and then clean the valve hole. Even small particles of foreign matter between the seat and the ball may damage the seat sealing surface.
1.2 Installation steel ball valve
(1) Install the valve on the pipeline. Any end of the valve can be mounted on the upstream end. Valves driven by the handle can be mounted anywhere on the pipe. However, ball valves with gearboxes or pneumatic drives should be installed upright, that is to install on horizontal pipes, with the drive above the pipe.
(2) A gasket is installed between the valve flange and the pipeline flange according to the piping design requirements.
(3) The bolts on the flange should be tightened symmetrically, successively and evenly.
(4) Connect the pneumatic line (when using a pneumatic drive).
1.3 Post-installation inspection(1) Operate the drive to open and close the ball valve several times. It should be flexible and free of stagnation, and it is confirmed that it is working normally.
(2) Check the sealing performance of the flange joint between the pipe and the ball valve according to the pipeline design requirements.
Stainless steel ball valves just need operation of rotating 90 degrees of and a small turning torque to close tight. The fully equal valve body cavity provide the medium a straight-through flow path with a small obstruction. The main features of the ball valve are its compact structure, easy to operate and maintain. The stainless steel ball valve can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. The ball valve body may be integral or combined. This type of valve should generally be installed horizontally in the pipeline. Stainless steel ball valve can be divided into stainless steel pneumatic ball valve, stainless steel electric ball valve, stainless steel manual ball valve. Material of Stainless steel ball valve include SS304, SS316 and SS321.
Stainless steel ball valve Working principle:The ball valve works by rotating the valve plug to make the valve unblocked or occluded. The ball valve switch is light in weight, small in size, can be made into a large diameter, reliable in sealing, simple in structure, convenient in maintenance, and the sealing surface and the spherical surface are often closed, and is not easily eroded by the medium, and is widely used in various industries.
The ball valve and the plug valve(cock valve) are the same type valve, only the closing member of which is a ball, and the ball rotates around the center line of the valve body to open and close a valve.
The ball valve is mainly used in the pipeline to cut, distribute and change the flow direction of the medium. Ball valves are a new type of valve that is widely used.
Advantages of stainless steel ball valve:1. The fluid resistance is small, and its resistance coefficient is equal to the pipe length of the same length.
2. Simple structure, small size and light weight.
3. Tight and reliable, the sealing surface material of the ball valve is widely used in plastic and has good sealing performance. It has also been widely used in vacuum systems.
4. It is easy to operate, and it can be opened and closed quickly. It can be rotated by 90° from full opening to full closing, which is convenient for long-distance control.
5. Easy maintenance, the ball valve has a simple structure, the sealing ring is generally active, and it is convenient to disassemble and replace.
6. When fully open or fully closed, the sealing surface of the ball and the seat is isolated from the medium, and the medium does not cause erosion of the sealing surface of the valve.
7. Wide range of applications, from small to a few millimeters, up to a few meters, from high vacuum to high pressure.
Ball valves have been widely used in petroleum, chemical, power generation, paper, atomic energy, aviation, rocket and other departments, as well as people's daily lives.
In China market, normally the heavy type stainless steel ball valve are from North factories, the compact type are mostly made by south plants. So if you more care about the price and have lower budge, then you can consider the compact type ball valve, in short time there is no much differences between heavy type and compact type, but maybe 5-6 years later then you can find that the compact stainless steel ball valve need to be replaced by a new one, while the heavy ball valve are still good enough to performance its all functions in your plumbing.
Meanwhile I suggest customers to buy the stainless steel ball valve from a big factory. Even some small mills can also make stainless steel ball valve, but most of theirs finished product more or less will have some flaws, for example there is no deburring & shot blasting treatments or their treatment is not strict, their polishing is rough(not ideal). more over the size of final castings can not be correspond with their drawings.
Compared with forging process, castings process is to pour the stainless steel liquid into the molds, so if you have a higher requests for your parts, we advise you to make it by casting workshop not forging workshop.
You would better to purchase stainless steel ball valve from a big investment castings manufacturing factory.
With the development of the lost foam casting, people pay more attention to the lost foam casting. It is reported that the refractory material is the aggregate composition of the lost foam coating, a lot of variety of refractory materials, usually choose the following five:
The main components of zircon powder are ZrO2 and SiO2, namely, the zirconium silicate. Its high degree of fire resistance, is now used for lost foam casting the best one of the anti sand. Cast steel castings and large cast iron parts, the use of such refractory materials, can reduce the workload of the cleaning of the casting, to obtain a smooth surface of the castings.
The main component of quartz powder is SiO2. Because the quartz powder has different crystal form transformation under different temperature conditions, the volume change of the quartz powder is changed, thereby reducing the use value of the quartz powder. Generally used to cast columns of cast iron and aluminum, copper and other non-ferrous metal parts. The EPC is mainly used in small, so the common application of quartz powder.
Alumina is corundum powder, the main component is Al2O3. It is also a kind of excellent performance of refractory materials, can be used to cast steel castings and large cast iron parts.
Graphite powder is one of the refractory materials used in the production of cast iron. It has a high degree of fire resistance, but it is easy to be oxidized. Its thermal expansion coefficient is very low, generally within 50 x 10-7.
Kyanite refractoriness at 1800 degrees, and kyanite in high temperature 1100-1450 degree gradually transformed into mullite, mullite 1800 is still stable, 1810 degrees is decomposed into corundum. Kyanite has relatively low price, is the ideal substitute for mineral corundum materials.