Metal Seated Ball Valve: Abrasive and High-Temperature Service

Ball Valves

In a metal seated ball valve, the ball and seats seal against each other on hard-faced metal surfaces instead of soft inserts. It provides long service life where PTFE and similar soft seats degrade quickly because of solid particles, catalyst, ash, slurry or high temperature.

Metal-to-metal seatsTungsten carbideChromium carbideHigh temperature
Three-piece forged body ball valve, bare stem

Overview

The ball and seat surfaces are coated with hard facings such as tungsten carbide, chromium carbide or Stellite and lapped together as a matched set. The shutoff class differs from that of soft-seated valves; allowable leakage is defined by API 598 or by the class stated in the specification.

The design can be applied to both floating and trunnion mounted valves. Selection considers temperature, particle size and hardness, cycling frequency and the required shutoff class together.

Technical specifications

DesignFloating or trunnion mounted; metal-to-metal seats
CoatingTungsten carbide (HVOF), chromium carbide, Stellite; lapped matched set
Pressure classASME Class 150–2500 (by type and size)
MaterialsWCB, WC6, WC9, CF8M, duplex; to suit the service
ApplicationsAbrasive particles, high temperature, slurry, catalyst and ash lines

Key features

  • Long life at temperatures and wear levels that soft seats cannot withstand
  • Lapped ball-to-seat matching
  • Coating type and thickness selected for the service
  • Shutoff class stated clearly in the quotation

Catalog data

  • Body: 3-piece forged or cast body; easy to dismantle for maintenance.
  • Ball and seat coatings: tungsten carbide (HVOF), chromium carbide, CoCr hardfacing (Stellite); ball and seats are lapped as a matched pair.
  • Operation: bare stem with ISO 5211 mounting pad, ready for actuation; for high torque, sizing is done at quotation stage.
  • Leakage class: on request, tested to ANSI/FCI 70-2 Class V or API 598 metal-seated leakage criteria.

Documentation and testing

On industrial projects the documentation package matters as much as the valve. We confirm the certificate and test scope for every line item at quotation stage:

  • EN 10204 3.1 material certificates for pressure-retaining and wetted parts, traceable by heat number
  • EN 10204 3.2 with third-party inspection, on request
  • Pressure test reports to API 598 or EN 12266-1: shell, seat and, where specified, gas tests
  • Fire-test certificates (API 607 / ISO 10497) for fire-safe type-tested designs
  • PMI reports for alloy and stainless materials
  • Dimensional, visual and coating inspection records
  • PED 2014/68/EU CE declaration for equipment within its scope
  • NACE MR0175 / ISO 15156 compliance statement for sour (H₂S) service

Technical datasheet

Frequently Asked Questions

Does a metal seated ball valve provide zero leakage?

With the right coating and lapping, very low leakage rates can be achieved; however, the acceptance criterion differs from soft-seated valves and is defined by the shutoff class in the standard or specification. We state the target class in our quotation.

Which coating should be selected?

Tungsten carbide is common for abrasive particles and high-velocity flow, chromium carbide for higher temperatures, and Stellite for general hard-facing needs. The choice depends on temperature, particle hardness and corrosion conditions.

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