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Metal Seated Ball Valve Coating Options

What are “Metal Seats”?

Metal seated valves represent the fastest growing (by %) segment of the valve industry. These seats can be found in ball valves, butterfly valves, plug valves and others.
  • Base Metal Contact (Gate and Globe Valves – Not Sliding Wear)
  • Coated or Modified Metal (Most Common)
  • Stellite Weld Overlay (Usually Stellite VI – Cobalt Based)
  • “Surface Modification” of Sealing Surfaces: Ex. Nitriding, Boronizing, etc.
  • Plating: Ex. Chromium Plating or ENP (Electroless Nickel Plating)
  • HVOF Coating: Tungsten and Chromium Carbide are the most common
  • Fused or Vacuum Deposition of “Coating” typically Tungsten Carbide
  • There is no “One size fits all” for “Metal-to-metal” sealing. Coatings are very application dependent.
Metal Seated Valve Coating
1. HP-HVOF Process
  • Chrome Carbide, Tungsten Carbide, Chrome Oxide and other specially formulated coatings.
    • Cr3C2-NiCr
    • WC-Co / WC-Ni  /  WC-Co-Cr  /  WC-CrC-Ni
  • Coating mechanically bonds to the Substrate Material.
  • Mechanical bond – >12,000 psi bond strength for Carbides, 5,000 – 7,000 psi for Chrome Oxide Ceramic.
  • Robotically positioned spray gun creates high kinetic energy allowing the coatings to be applied in a compressive state.
  • Problems:
    • Porosity – Poor Sealing on Gas
    • Carbon Content makes these coatings vulnerable to Oxidation.
Ladish Valve Coating Technology

Ladish Valve Coating Technology

2. Spray & Fused Process
  • Substrate material becomes annealed due to fusing temperatures; subsequent heat treatment required.
  • Semi-molten coating “sags” or “sloughs” – gravity effect
  • Coated Surface is “finish” machined using either CBN (cubic boron nitride) or PCD (polycrystalline diamond) tooling.
  • Very Low Porosity – Best for small molecule gas and particles smaller than 1 micron.

Once again, Ladish will continue To Mark Progress.

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We are excited to announce that effective November 1, 2020 we have purchased the trademarks and all assets related to Smith Valves & Diamond Gear from CNC Flow Control!