It is recommended to use cast iron for general Dalian marine valves, and the environment you mentioned may be close to the river and seawater environment, which is also recommended to use cast iron. Therefore, it is recommended to use cast iron as the valve material.
There are many types of valves. According to their functions, they are mainly cut-off, regulating, check, distributing, safe, and other functions, such as steam blocking and drainage, venting, and blowdown.
Shut off valve
This type of valve is used for opening and closing. It is always used at the inlet and outlet of cold and heat sources, the inlet and outlet of equipment, the branch line of pipeline (including riser), and can also be used as the drain valve and vent valve. Common shut-off valves include gate valve, globe valve, ball valve and butterfly valve.
Gate valves can be divided into rising stem and non rising stem, single ram and double ram, wedge ram and parallel ram, etc. The tightness of the gate valve is poor, and the opening of the large diameter gate valve is difficult; The valve body size is small along the flow direction, the flow resistance is small, and the nominal diameter span of the gate valve is large.
This type of valve is used to prevent the backflow of media. It can be opened automatically by using the kinetic energy of the fluid itself and closed automatically when reverse flow occurs. It is always used at the outlet of water pump, the outlet of steam trap and other places where reverse flow of fluid is not allowed. Check valves are divided into swing type, lift type and wafer type. For swing check valves, when the fluid can only flow from left to right, it will automatically close when it flows in the opposite direction.
The pressure difference between the front and back of the valve is fixed. When the opening of an ordinary valve changes in a large range, its flow changes little. When it reaches a certain opening, the flow changes sharply, which means poor regulation performance. The regulating valve can change the resistance number of the valve by changing the stroke of the valve element according to the direction and size of the signal, so as to achieve the purpose of regulating the flow.
Vacuum includes vacuum ball valve, vacuum flapper valve, vacuum charging valve, pneumatic vacuum valve, etc. Its function is to change the air flow direction, adjust the air flow, and cut off or connect the vacuum system elements in the vacuum system, which are called vacuum valves.
Special purpose category
Special purpose categories include pigging valve, vent valve, blowdown valve, vent valve, filter, etc. Exhaust valve is an indispensable auxiliary component in the pipeline system, which is widely used in boilers, air conditioners, oil and gas, water supply and drainage pipelines. It is often installed at the commanding point or elbow to eliminate excess gas in the pipeline, improve the service efficiency of the pipeline and reduce energy consumption.