When selecting a ball valve, you’re faced with a myriad of options. Materials of construction, the proper size, and the right design (1, 2, or 3 pieces, V-port, double block and bleed, etc.) are all critical pieces to the puzzle. Just as important is the seat type you’ll select.
Completely understanding your process conditions is the first step to selecting a seat for your valve. Will the fluid be corrosive? Contain abrasive particulate? Be at high temperatures or pressures? Require bubble-tight shut-off? Once you know these things, the choice is clear.
Soft Seated Ball Valves
Soft seats are generally made of thermoplastic materials like PTFE. They’re great for applications where chemical compatibility is important, and where the tightest seal is key.
However, soft seats are not recommended for process fluids that are dirty, or abrasive. Soft seats can break down in these conditions, causing the valve to leak.
Metal Seated Ball Valves
The primary advantage of metal seated valves over soft seated valves is their ability to withstand high temperatures and severe service conditions. Metal seats can endure severe flashing, hydraulic shock, abrasive process fluid, and high temperatures up to and exceeding 1,000° F. They are also ideal for high erosion or corrosion applications.
Metal seats can be hardened by coatings like ultrasonic spray coating, satellite hard facing, chromium carbide and tungsten carbide.
Which Is Right For The Process?
The upfront purchase price of a metal seated ball valve is definitely more than a soft seated ball valve. However, one should consider the cost of downtime and replacement of a soft seated valve. Total cost of ownership may favor the metal seat.
Understanding your process conditions is key to determining the right seat for your application. If the selection is still unclear, speak with an engineer who is well versed in valve selection to help determine the best solution.
Need help selecting a seat for your application? Ask us about it! We gladly provide technical assistance on valves to businesses and municipalities throughout the United States.