Metal & Graphite Seated Ball Valves – Designs and Applications
Content provided by Barry Hoeffner
Metal Seated Valve Coatings
Metal seated valves represent the fastest growing (by %) segment of the valve industry. These seats can be found in ball vales, butterfly valves, plug valves and others.
- What are “Metal Seats“?
- Dissimilar Metals (Old Technology no longer widely accepted)
- 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.
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.
Spray & Fused Process – Colmonoy
- 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.
Vacuum Testing of Valve Trim Sets Prior to Installation
Ladish ball & seat
“Critical” Service Ball Valves – MEGA Seal
| GRAPHITE SEATED | METAL SEATED |
| Class 300 and 600 | Class 150 – 600 |
| Flanged Ends | SW/BW, RFF, RTJ End Connection Possible |
| ¾” – 8” | Inserted Seats (Repairable Design) |
| Split Body or Unibody, Full or Reduced Port | .5” – 14” |
| Target Market: Clean High Temperature and Acid Service with Temperatures above 450F (up to 1000F) | Target Market: Refining and Chemical, Severe Service
•High Temperature •Solids Handling •ETHYLENE and VCM •Alloy Options include 316SS, Monel, Inconel, etc. |
| Tight Shut-Off Capability | |
| Full Alloy Options (Hastelloy, Inconel, Incoloy, Monel, etc.) | |
Severe Service Ball Valves
| POWER VALVE | ENGINEERED METAL SEATED |
| Class 900/1500, 2500 (3100) & 4500 | Class 150 – 2500 |
| Welded – Ends (SW / BW) | SW/BW, RFF, RTJ End Connection Possible |
| .5” – 3” | Inserted Seats or Captured Flange (Repairable Design) |
| Forged (Machined from bar), 2-piece construction | .5” – 14” |
| Target Market: Thermal Power & High Pressure Steam / Hydrocarbons | Target Market: Refining and Chemical
•High Temperature •Solids Handling •Coking / Fouling Services •Automated on/off & high cycle |
| Tight Shut-Off Capability | |
Ladish “T” Series Power Valve:
| APPLICATIONS – ISOLATION, VENTS & DRAINS |
| Size: ½” – 3” |
| A105, F22, F91, F92 & others |
| Ball & Seat
•410 SS – HP-HVOF (Cr3C2-25NiCr) •Inconel 718 – Fused ((CrB – Cr3C2 ) |
| Pressure Class
•1500# – 4500# |
| Bore Sizes
•.65”, 1.00”, 1.50” (1500#, 2500#,/3100#) •.65, 1.00” (4500#) |
| 2-Piece Construction |
| Uni-directional (Std.) |
Engineered Severe Service Metal Seated Ball Valve:
I. Initial Target Applications
- Automated On/Off and High Cycle Applications
- High Temperature Isolation (Generally >600F)
- Solids Handling (eg. FCCU Catalyst, Coke Fines, Hot Gas Service with Fines)
- Gasification
- Polyethylene and Polypropylene
- Acid Leaching of Minerals
- High Pressure Steam and Boiler Feedwater in the Process Industries
II. Two “Flavors” of the Ladish Severe Service Valves
- Captured Flange” to create better resistance to High Temperature “Thermal Shock” and allow reparability.
- Inserted Seat for designs with short Face-to-Face (eg. Class 150 and 300 Flanged) and used in larger Bore (>8”) applications.
Note: Valves have a preferred sealing direction but can be configured for full bi-directional service.
Severe Service Metal Seated Ball Valve:
FCCU Critical Ball Valves:
Chrome alloy valves for temperatures to 850F, 321SS for temps to 1400F.
For more information on the MEGA Seal or Severe Service lines, please contact us! sales@ladishvalves.com or 281.880.8560. View more details on the MEGA Seal line here.
Once again, Ladish will continue To Mark Progress.
We’re Social @LadishValves
