Gate valve is an important pipeline control equipment with an extremely wide range of applications. It is a device that can control the opening and closing of valves through gates. It is often used for flow regulation, cutoff and pressure regulation in pipeline systems. Gate valves are very important to industrial production and daily life, and different types are produced according to people’s needs.In this article TWT,China will introduce gate valves to buyers from three aspects.
The size of gate valve
The diameter of gate valves is generally larger, above 2 inches. Commonly used gate valves range in size from 2 inches to 80 inches.
- Small size gatevalve: nominal size DN≤40mm.
- Medium size gatevalve: nominal size DN50~300mm.
- Big size gatevalve: nominal size DN350~1200mm.
The fluid resistance of big size gate valve is relatively small, and the use of big size gate valve can effectively reduce energy consumption during fluid transportation.
The working site of gate valve
Above-ground gate valves are more common because they generally refer to valves installed directly above or on the adjacent side of the pipeline for easy operation and maintenance.
The underground gate valve is a special gate valve that can be directly buried underground to control the flow of pipelines buried deep underground. The main feature of the underground gate valve is that the gate plate that moves up and down serves as the opening and closing component of the valve. The valve stem of the underground gate valve is extremely long and can be customized with different lengths according to different usage environments, which can meet the usage requirements of various municipal pipeline constructions. Because underground gate valves have been buried below the surface for a long time, the working environment is harsh, and replacement and maintenance are inconvenient. Therefore, when choosing underground gate valves, the quality of the valve should be considered.
The material of gate valve
The material of the gate valve should first consider the physical properties (temperature, pressure) and chemical properties (corrosiveness) of the working medium. At the same time, you should also know how clean the media is (whether there are solid particles). In addition, you must also refer to the relevant regulations and requirements of the country and the user department.
Many materials can meet the requirements of gate valves in various working conditions. However, correct and reasonable selection of valve materials can achieve the most economical service life and best performance of the valve.
1.Gray cast iron gate valves are used in various fields of industry due to their low price and wide range of applications. They are usually used in the media of water, steam, oil and gas, and are widely used in chemical industry, printing and dyeing, oil chemical industry, textile and many other industrial products that have little or no impact on iron pollution.
It is suitable for low-pressure valves with operating temperatures between –15 and 200°C and nominal pressures PN≤1.6MPa.
2.Ductile iron gate valve is a type of cast iron. In this cast iron, lump or spheroidal graphite replaces the flake graphite in gray cast iron. This change in the internal structure of the metal makes its mechanical properties better than ordinary gray cast iron without damaging other properties. Therefore, valves made of ductile iron will operate at higher pressures than those made of gray cast iron. It is suitable for medium and low pressure valves with working temperature between –30~350℃ and nominal pressure PN≤4.0MPa.
Applicable media are water, seawater, steam, air, gas, oil, etc.
3.Low-temperature carbon steel (LCB) gate valvecan be used in sub-zero temperature ranges, but their use cannot be extended to cryogenic areas. Valves made of these materials are suitable for media such as seawater, carbon dioxide, acetylene, propylene and ethylene.
Suitable for low-temperature valves with operating temperatures between –46 and 345°C.