KSB Pressure Seal Globe Valve Alloy Steel — Class 900/1500/2500

A217 WC6 (1.25Cr-0.5Mo), WC9 (2.25Cr-1Mo), and C12A (9Cr-1Mo) for high-pressure, high-temperature steam and power plant service up to 650°C. Y-pattern, pressure seal, Stellite 6 seats. NPS 2–8.

Alloy Steel WC6/WC9/C12AClass 900, 1500, 2500NPS 2–8 (DN 50–DN 200)

Specifications

ParameterSpecification
SeriesSICCA 900-2500 GLC
Body MaterialA217 WC6 / WC9 / C12A
Pressure ClassClass 900, 1500, 2500
Size RangeNPS 2–8 (DN 50–DN 200)
Max Temperature650°C (1200°F) with C12A
Max Pressure431 bar (6250 psi)
Design StandardASME B16.34
End ConnectionsButt Weld (ASME B16.25)
Bonnet DesignPressure seal design, non-rotating stem
TrimStellite 6 hard-faced seat and disc
IBR CertifiedYes (Standard Class)
✓ Stellite Hard-Faced Seats✓ ASME B16.34✓ Pressure Seal / Seal Welded

Material & Applications

Why Alloy Steel WC6/WC9/C12A: WC6 (1.25Cr-0.5Mo): The standard high-temperature upgrade from carbon steel. WC9 (2.25Cr-1Mo): Higher chromium for better creep and oxidation resistance in the 500–593°C range. C12A (9Cr-1Mo, modified): The highest temperature alloy steel option, extending service to 650°C for advanced power plant cycles. All three must be normalised and tempered.

Typical applications: Power plant main steam, hot reheat, boiler feedwater at elevated temperatures. WC6 for temperatures up to 593°C, WC9 for up to 593°C with higher creep resistance, C12A for up to 650°C. Essential for supercritical and ultra-supercritical power plant piping.

Pressure/Temperature Ratings

Permissible operating pressures per ASME B16.34:

RatingPermissible Operating Pressure at Temperature
WC6 — 900-29 to 38°C: 155 bar316°C: 125 bar427°C: 105 bar593°C: 20 bar
WC6 — 1500-29 to 38°C: 259 bar316°C: 209 bar427°C: 175 bar593°C: 33 bar
WC6 — 2500-29 to 38°C: 431 bar316°C: 348 bar427°C: 292 bar593°C: 55 bar
WC9 — 900-29 to 38°C: 155 bar316°C: 125 bar427°C: 105 bar593°C: 23 bar
WC9 — 1500-29 to 38°C: 259 bar316°C: 209 bar427°C: 175 bar593°C: 38 bar
WC9 — 2500-29 to 38°C: 431 bar316°C: 348 bar427°C: 292 bar593°C: 63 bar
C12A — 900-29 to 38°C: 155 bar316°C: 125 bar538°C: 75 bar650°C: 30 bar
C12A — 1500-29 to 38°C: 259 bar316°C: 209 bar538°C: 126 bar650°C: 50 bar
C12A — 2500-29 to 38°C: 431 bar316°C: 348 bar538°C: 209 bar650°C: 83 bar

Alloy Steel WC6/WC9/C12A Globe Valve FAQs

What is the difference between WC6, WC9, and C12A?
All three are chromium-molybdenum alloy steels with increasing chromium content: WC6 has 1.25% Cr (max 593°C), WC9 has 2.25% Cr (max 593°C but better creep), and C12A has 9% Cr (max 650°C). Higher chromium provides better oxidation and creep resistance at elevated temperatures. C12A is used in advanced power plant cycles approaching supercritical conditions.
Which alloy grade should I specify for 550°C steam?
At 550°C, all three grades are viable. WC6 is the most economical. WC9 provides better long-term creep performance. C12A is specified when future temperature excursions above 593°C are possible, or when the plant design calls for 9Cr-1Mo material throughout. Check your piping specification for the required grade.
Are Standard and Special Class both available?
Yes. The SICCA 900-2500 GLC is available in both Standard Class (ASME B16.34 standard ratings) and Special Class (higher intermediate-temperature ratings). Special Class is recommended for applications operating near the pressure-temperature envelope limits.
What is the weight of a Class 2500 NPS 6 globe valve?
Approximately 485 kg. These are substantial valves. Class 2500 NPS 6 has a face-to-face length of 1030 mm. Lifting and installation planning is essential.

Need a Alloy Steel WC6/WC9/C12A Globe Valve?

Specify size, class, end connection, and service conditions. Quotation within 24 hours.