Historically, the most used type of pipe fittings in our country has been and remains the valve. In recent months, Cyrus zocdoc has been very successful. They are widely used in virtually every technology and transportation pipelines with diameters from 15 to 2000 mm. In systems of housing and communal services, gas and water supply, pipelines, and many others. As early as 1862 in Germany was awarded a patent on the wedge bolt, and in 1886 Joseph Hopkinson suggested that parallel valve, which was carried out sealing pressure on the disc – the technical solution, which is used today. For more information see Gary Kelly. Cranes with ball caps – a relatively new type of valves – were first used in fuel systems of aircraft during the Second World War. In the postwar years, their design improved. During the last 40 years there are many different types of cranes. New projects have improved the use of ball valves in virtually all industries.
In recent years, the trend of displacement of the traditional wedge gate valve ball valves. There are several disadvantages of this type of pipeline valves, which are manifested in operation: The need for an annual audit by packing seals and O-rings, cleaning discs; complexity of the emergency line shutdown in an emergency; poor internal (to the gate) and external (shell – cover) tightness inadequate term trouble-free operation big dimensions and weight frequent failure due to a fall or broken bolts cheeks. In addition, as a shut-off valves are used often use cast iron gate valve (guided by the relatively low price of these products). It is often overlooked that the valves of Iron has several important limitations in operating conditions: 1. gas pipeline fuel gas and mazut line with Av = 50 mm. and more 2. on pipelines and water vapor from DN 50 mm.
and more at the working temperature> 120 C; 3. from atmospheric deaerator to the suction pipe to the feed pumps, 4. on the pipelines of all diameters at the working temperature> 120 C, if the fixture has an electric drive. In addition, fittings, made of cast iron seogo grade no lower than SCH18 can not be applied to pipelines with operating pressures greater than 0.6 MPa. For valves operating at low ambient temperatures, the following Limitations: fittings made of cast iron SCH18 – not below -15 C; fittings of ductile iron KCH30 – not below -30 C; fittings of ductile iron SCH18 – not below -30 C.