When should you use metal-to-metal seat?

Temperatures beyond soft-seat material limits (typically above ~200-260C depending on the polymer) Abrasive or erosive services (slurry, catalyst, high-solids) where a soft seat would wear quickly Services where a small, allowable leakage class (not bubble-tight) is acceptable per the governing standard

Sealing & Emission Control Systems

Seat Sealing

Metal-to-Metal Seat

The disc or ball seals directly against a hardened metal seating surface with no elastomer or PTFE element - trading the bubble-tight shutoff of a soft seat for temperature range, abrasion resistance and fire-safety by nature rather than by design feature.

How does metal-to-metal seat work?

Precision-lapped or hard-faced metal surfaces (often Stellite or tungsten carbide overlay) contact under seating load; sealing depends on surface finish and contact stress rather than an elastomeric element, so there is nothing to burn, extrude or chemically degrade.

When to Use It

Temperatures beyond soft-seat material limits (typically above ~200-260C depending on the polymer)
Abrasive or erosive services (slurry, catalyst, high-solids) where a soft seat would wear quickly
Services where a small, allowable leakage class (not bubble-tight) is acceptable per the governing standard

Limitations

Cannot achieve bubble-tight (zero-leakage) shutoff - leakage class is a defined allowable rate, not zero
Higher torque to seat and unseat than an equivalent soft-seated valve
Seat and disc lapping/re-grinding is a specialised maintenance skill, unlike soft-seat replacement

Typical MaterialsStellite overlay; tungsten carbide coating; hardened 13Cr or duplex stainless

Used OnGate Valves Globe Valves Ball Valves Check Valves