Village roads damaged valve to gas leakage

Yesterday morning at 9 o 'clock, daxing district zaoyuan village residents and the surrounding neighborhoods has experienced a false alarm.Originally, is gas leakage happened in the construction site near the village square, some residents were evacuated, emergency closed around the elementary school, thankfully, the scene quickly under control and processing.
Jujube jujube village is located in the subway line 4 station northwest edge.Journalists arrived, squares and fitness between garden has pulled the cordon, the ground has a diameter of about one or two meters of the holes, the workers and the excavator is working.
The reporter understands, around eight o 'clock yesterday morning, residents near the pit smelled a smell of abnormal, before here is building a road, convenient zaoyuan primary school students and parents from the north side of pass in and out.So some suspect, may be road construction in buried gas pipeline leak.
News is reflected in the residents' committees, the staff quickly get in touch with gas, construction.Then, property management, police, fire, gas sector have arrived at the scene, the firemen hose ready for a rainy day.Considering the safety of nearby residents, residents' committees sent notice the holes around a few hundreds of residents in the building, will they evacuated.Zaoyuan primary school also temporary decided to listening to lectures, notify the parents to children away.
Fortunately, not as bad as fuel gas, property management department closed gate, smell fades.At noon, the residents have returned home.According to the staff of the residents' committees, the cause of the accident is the construction personnel touch is broken when working in a gas valve, lead to gas leakage fault has repair, then backfill earthwork, is expected soon to restore gas supply.

(source:http://www.kg-machinery.com/news/valve.html)

History of valve

The valve is produced with the flow of the fluid pipe. Human use of the valve has been nearly 4000 years of history. Chinese ancient salt brine from salt in absorption, once in the bamboo pipe used in cork valve. In the 1800 BC, the ancient Egyptians used similar wooden plug to control the flow of water in order to prevent the Nile flood. These are the valve prototype. Industrial use of the valve is a large number of applications, from the beginning of the invention of the steam engine Watt. At the beginning of twentieth Century has cast iron, cast steel, forged steel, stainless steel, chrome molybdenum steel, brass and other materials in the valve. Application in various industries, various conditions. The earliest introduction of foreign valve production technology company is not much, after the introduction of foreign production technology, making the domestic valve production technology breakthrough, the quality of the increase, the longevity of the extension.
According to the "2013 China valve industry competition development bottleneck" in the show: with the valve industry to accelerate the pace of restructuring, the industry will be the valve product quality safety and product brand competition between products to high technology, high parameters, high resistance to corrosion, high life direction, only through continuous technological innovation, development of new products, technological transformation, to gradually improve product technology level, to meet domestic equipment supporting, the full realization of the domestic valve. China's valve manufacturing industry in a huge demand environment, will show a better development prospects.
At present, China's valve market turnover of up to 50000000000 yuan, which fully shows the size and momentum of the development of the valve industry in china. But in the industry situation in a good background, there are some problems worthy of our concern, especially in China's valve business mainly in the low level, small scale, family business oriented enterprises. This is a great limitation and bottleneck for the future development of the valve industry in China.
At present, the domestic valve manufacturing enterprises have been able to ISO international standards, DIN German standard, AWWA American Standard and other international standards for design and manufacture of various valves, some manufacturers of products reached the international advanced level. Although the new year's overall level of the valve industry has been greatly improved, but the quality is still not stable enough, such as run, run, drip, leakage phenomenon in the domestic valve often occur.
In addition, the matching capacity of the valve with the developed countries, there is still a certain gap. Valve market competition is becoming increasingly fierce, some ordinary valve products market has been saturated, for more than a request, which makes the development of small and medium enterprises increasingly difficult. And even the high technology products in the international market is also very fierce competition.
Our country in the valve market, has been able to provide heating valve, environmental protection valve, construction valve, etc., more varieties.

（source:http://www.kg-machinery.com/news/history-of-valve.html）

The structure of valve

As an opening and closing of valve, it is mainly composed of valve body, artifacts and cover for opening and closing of three parts. Seat on the valve body, valve stem drive valve opening and closing (disc) make lifting movement, the clutch disc and seat, the valve opening and closing.
Opening and closing mechanism by disc (also called valve disc, valve core), stem and drive device (hand wheel).Stem with trapezoid thread screw on the cover, the handwheel and disc fixed on both ends of stem up and down, turn the handwheel, the stem rises or falls, near or leave to drive the valve seat valve to close and open, disc and seat close match, the disc by the pressure of the valve stem compression on the seat, when the valve is fully closed position, the valve does not leak tight.

（source：http://www.kg-machinery.com/news/the-structure-of-valve.html）

The definition of valve

Definition: valve is in the fluid system, used to control the direction of the fluid, pressure, flow device. The valve is a device that make piping and equipment within the medium (liquid, gas, powder) flow or stop and can control the flow. Valves can be used to control air, water, steam, a variety of corrosive media, mud, oil, liquid metals and radioactive media and other types of fluid flow. Valve is control unit in the pipeline fluid conveying system, it is used to  change the channel section and flow direction of medium, have river diversion, cut-off, throttling, non-return, diversion or overflow pressure relief, and other functions. Used for fluid control valve, valve from the simple to the very complex automatic control system used in a variety of valves, its breed and specification is various, nominal size of the valve from the tiny instrument valve to size up to 10 m industrial pipe with a valve. Valve can be used to control water, steam, oil, gas, mud, all kinds of corrosive medium, liquid metal and radioactive fluid and so on various types of fluid flow, working pressure valves are available from 0.0013 MPa to 1000 MPa ultrahigh pressure, working temperature from 269 ℃ ultra-low temperature to 1430 ℃ high temperature. Valve control can use a variety of transmission way, such as manual, electric, hydraulic, pneumatic, turbine, electromagnetic actuator, electromagnetic hydraulic, electric hydraulic, hydraulic, spur gear, bevel gear drive, etc; Under pressure, temperature or other forms of sensor signal, according to the predetermined requirement, or does not rely on the sensing to carry on the simple open or shut down, valve to rely on drive or automatic mechanism makes opening and closing parts for lifting, slip, swirl pendulum or rotary motion, thus changing the area of the channel size in order to achieve its control function.

（source：http://www.kg-machinery.com/news/the-definition-of-valve.html）

The valve sealing requirements

Valve sealing performance refers to the sealing parts of valve's ability to prevent leakage of medium, it is the most important technical performance index of the valve.There are three sealing parts of the valve : open-close part and seat the contact point between the two sealing surface;Packing cooperate with stem and packing gland;The joint of the body and bonnet.One former place called internal leakage of leakage, known as the closed lax, it will affect the valve truncation medium capacity.For block valves class, the internal leakage is not allowed.After the two called the outside leakage, the medium from leaking to the outside of the valve from the valve.Leakage would cause material loss, environmental pollution, serious when still can cause accidents.For flammable and explosive, toxic or radioactive medium, leakage is not allowed, so the valve must have a reliable sealing performance.

（source：http://www.kg-machinery.com/news/the-valve-sealing-requirements.html）