The difference between metal seated ball valve and soft seated ball valve
What are the differences between metal sealed ball valves and soft sealed ball valves? Hereby we specify the details difference on aspects like their materials, pressure and temperature resistance, sealing performance, and price.
Material difference：
The seat material of metal seated ball valve, mostly made of stainless steel and hard alloy seal. The soft sealed valve seat is divided into PTFE, RPTFE, NYLON, PEEK, PCTFE, etc. (We will specify the different working conditions for different soft seat materials in next topic)
Temperature and pressure are different: Metal seated ball valve have a wide range of applications, suitable for both low and high temperatures, and are generally used for metal sealing in high temperature and high pressure conditions. Soft seals are often used in atmospheric and low-temperature conditions
Different leakage levels: Metal sealed ball valves generally with leakage Class V, but can also achieve a leakage Class VI. The general leakage level of soft sealed ball valves is Class VI
The sealing performance is different: the two sides of the sealing pair are made of metal materials or harder materials, which are called "hard seals". This type of seal has poor sealing performance, but is resistant to high temperature, wear, and good mechanical properties, such as: steel+steel; Steel+copper; Steel+graphite; Steel+alloy steel; The steel here may also be cast iron, cast steel, alloy steel, or alloy steel that is welded or galvanizated. The two sides of the sealing pair, with one side made of metal material and the other side made of elastic non-metallic material, are called "soft seals". This type of seal has good sealing performance, but is not resistant to high temperatures, is prone to wear, and has poor mechanical properties, such as steel and PTFE. The advantage is good sealing performance, but the disadvantage is easy aging, wear, and short service life. Hard seals have a long service life, but their sealing performance is relatively worse than soft seals.
Price difference:
Hard sealed ball valves are much more expensive than soft sealed ball valves.
Soft sealing is cheap and easy to achieve good sealing effects. But in petrochemical production facilities, soft seals can only be used in extremely limited situations such as finished product loading, and cannot be used in other situations, almost considered useless.
The reason is simple: there are inevitably particles and other substances in the medium inside the device. Don't tell me that there are no welding rods, stones or other debris in the pipeline of the new device, which is difficult to clean and can easily damage the sealing surface.
Also, steam blowing is often used inside the device, as it is the entire device blowing, so it cannot be avoided in general places.
