Why did manufacturers initially launch metal seat ball valves?
Manufacturers introduced metal seat ball valves to the ball valve market to overcome several shortcomings of soft seated ball valves. Their ability to tolerate severe service conditions like flow control, slurries, abrasive mediums, cryogenic conditions, and high temperatures make them the best candidates for utilization in electric power production, steel and iron mill, water treatment, paper and pulp, mining, petrochemical, and oil refinery industries.
What material do manufacturers use to make metal seat ball valves?
Ball valves are quarter-turn, low-torque valves that pose low resistance to fluid flow. These valves suit process and on-off utility services. They are known for having nice control and straight-through configuration features, but plumbing professionals do not usually utilize them for throttling applications. Most ball valves are soft seated ball valves that utilize a thermoplastic substance known as nitrile butadiene rubber or polytetrafluoroethylene. Metal seat ball valve makers employ metal like Monel or three hundred and sixteen stainless steel as the seat substance of their metal seats. Plumbing experts recommend thermoplastic seals for tidy service only. They do not suit abrasive, dirty, or very low or high-temperature service. For very severe service uses, plumbing professionals prefer to use metal seat ball valves.
Applications and uses of metal seat ball valves
Metal seat ball valves feature a metal-to-metal sealing between the valve assembly’s ball and seats. Manufacturers produce these ball valves for the severe service of corrosives, abrasives, and high-pressure or high-temperature applications. Plumbing professionals usually use many metal seat ball valves for isolation and several for bi or unidirectional control as they tightly shut off valves in severe service uses. They adhere to specific leakage standards that permit no more than 0.01 percent leakage of whole open valve capacity.
For metal seat ball valves, the coating and structure of seats play a crucial role in deciding if the plumbing professionals use the valves with high temperatures or abrasives. Some seats feature elastomer insert elements that might degrade and lead to leakage when exposed to high temperatures. Many elastomer sealings feature a maximum temperature of about two hundred and twenty degrees Celsius. Other sealing options like metal powder-filled Teflon seats or similar substances permit for stretching the temperature to three hundred and fifteen degree Celsius. Suppose higher temperature resistance is required, particularly with every essential pressure. In that case, plumbing experts can use whole metal seats with hard coatings to attain temperature resistance of up to eight hundred and fifteen Celsius.
Coatings to help metal seated ball valves provide a severe service
Hard coatings are needed in severe-service uses where either high temperatures, hydraulic shock or severe flashing is anticipated or abrasion or corrosion resistance is required. Temperature resistance and prevention of ball and seat corrosion are essential. If operating temperatures exceed one hundred and fifty degrees Celsius, the coating will usually be tungsten carbide. For greater hardness and higher temperatures, plumbing professionals can utilize other carbides like cobalt-chromium alloys and chrome carbide to attain hardness values of greater than seventy plus Rockwell hardness and temperature values of up to eight hundred and fifteen Celsius. These coatings feature excellent abrasion and wear resistance when exposed to high temperatures to offer tight shut-off continuously.
Trunnion or floating metal seat ball valves
Almost every metal seat ball valve supplier sells metal seated ball valves in three-piece or two-piece designs, and depending on their magnitude, these ball valves could have either a trunnion or floating mounted ball, which vary in terms of how their manufacturers install the ball in them and how their seats seal against their ball. Manufacturers mechanically anchor the ball in trunnion valves at their bottom and top and utilize a line pressure and spring mechanism to push their upstream seat against the ball. The trunnion-mounted metal seat ball valve seal has a spring that holds the seat to the valve’s face during a revolution when there is low or no differential pressure. The liquid produces the sealing force by forcing the seat against the ball face. The design is generally for higher pressure and bigger valves.
Contrary to that, a floating metal seat ball valve has a more straightforward design because this ball valve features a floating ball that the trunnion has not anchored in the valve body. Floating ball metal seated valves offer excellent sealing performance but are mainly used in low or mid-pressure applications. The load put by a floating ball on the seat could be high; hence this explains why the diameters of floating ball valves rarely exceed six inches.
When to select trunnion vs. floating for metal seated ball valves?
When considering which metal seat ball valves to utilize for their operations, people must decide between trunnion or floating-style ball valves. There are two things that they should consider to help them select the right option.
Firstly, obviously, people need to consider cost as they are deciding to purchase a ball valve. Usually, floating ball valves are less costly than trunnion ball valves. This is because their production and design is less complicated than trunnion ball. They do not require extra shafts or spring-loaded seats to fix the ball in place, so they have lesser internal parts.
Nevertheless, people also need to consider their application. Floating ball metal seated valves tend to require greater torque to operate. This is particularly true as valve size and pressure rises. Thus, in high pressure applications, several people use trunnion style metal seated valves rather than floating ball metal seated valves. This is because these ball valves are more versatile and can tolerate greater pressures, and they are simpler to use in such conditions.
