We all know that when water is heated beyond its boiling point, it vaporizes into steam.
However, did you know that not all steam is equal?
Depending on the both the pressure and temperature that steam is exposed to, its properties can be very different.
Types of Steam
Saturated Steam: Results when heated water is heated to its boiling point and begins to vaporize.
Wet Saturated Steam: The most common form of steam. A Mixture of saturated steam that contains condensed water particles from water molecules that are not vaporized.
Dry Saturated Steam; Saturated steam that is free of water particles.
Super Heated Steam: When Saturated steam is heated beyond the saturated steam level. This yields steam that has a higher temperature and lower density than saturated steam have at the same pressure.
Steam and steam condensate are generally more corrosive than water due to the presence of dissolved gases, carbon dioxide, and oxygen. These elements can cause the steam and ball of the valve to corrode
Limitations of Ball Valves in Steam Service
In general, ball valves for steam service are rated at a lower temperature than for liquid or gas service. There are three main reasons for this:
- Wet steam can damage the ball when the ball is opened or closed or when throttling the valve.
- Opening and closing the valve can also damage the PTFE or RPTFE seats in the valve.
- Steam and steam condensate are generally more corrosive than water due to the presence of dissolved gases, carbon dioxide, and oxygen. These elements can cause the steam and ball of the valve to corrode.
How The JFlow DM4600 Series Ball Valves For Steam Service Solves These Limitations:
To solve the first problem of damage to the ball, the JFlow DM4600 series uses a vented ball with a 1/8” drill hole in the top of the ball slot to prevent excessive pressure build-up in the cavity from the trapped liquid when the valve is in the closed position.
The second issue is solved by using TFM 1600 seats and seals for low-pressure steam (261 psi @ 403°F) and by using TFM 4215 seats and seals for saturated steam and high-pressure steam. (378 psi @ 437°F)
The JFlow DM4600 Series Ball Valves for Steam Service solves the third limitation by the application of an electroless nickel coating (also known as autocatalytic coating). This is actually a nickel-phosphorus alloy. Electroless nickel has the unusual quality of being amorphous and not crystalline in structure. These coatings possess high hardness, uniform thickness, natural lubricity, extended service life and abrasion resistance. Shutdowns and delays in industries that use steam can be quite common because of the need to replace components, but as electroless nickel substantial extends the life of parts and components, a vast amount of money can be saved. The coating also provides an excellent surface condition for ball plugs and improves the sealing at the seat areas.
To learn more about the JFlow DM4600 Series Ball Valves for steam service click here