Technical Datasheet -- Pressure Seal Gate Valve -- Flexible Wedge WC9 High Pressure

Pressure Seal Gate Valve -- Flexible Wedge WC9 High Pressure

High-Pressure High-Temperature Isolation Valve for Main Steam and Reheat Service

Document No.SV-DS-GAT-009

RevisionRev A

DateMay 2026

ManufacturerSupreme Valves India, Ahmedabad, Gujarat, India

This datasheet covers high-pressure pressure seal gate valves in WC9 Cr-Mo steel with flexible wedge for main steam, hot reheat, and supercritical process isolation. Units are factory-tested and IBR-certified before dispatch.

Technical Specifications

Parameter	Specification
Valve Size Range	DN50 to DN400 (2" to 16")
Pressure Rating	Class 900 / Class 1500 / Class 2500
Body Material	WC9 (2.25Cr-1Mo) cast Cr-Mo steel, normalised and tempered
Wedge Material	SS316 + Stellite 6 hard facing, flexible wedge with centre hub
Seat Material	Integral SS316 + Stellite 6 overlay, lapped to wedge
Stem Material	17-4PH precipitation-hardened stainless steel, anti-galling
Bonnet Seal	Graphite pressure seal ring with segmented thrust ring
Packing	Pure graphite braided rings with Inconel wire reinforcement
Gaskets	Spiral-wound SS316 + graphite for body/bonnet and flange joints
Temperature Range	-29°C to +593°C (WC9 limit)
End Connections	Butt weld ASME B16.25, flanged ASME B16.5
Operation	Handwheel, bevel gear, motorised or hydraulic actuator
Features	Pressure seal bonnet, flexible wedge, full port, position indicator

Materials of Construction

Component	Material
Body	WC9 (2.25Cr-1Mo) cast steel, normalised 920°C, tempered 720°C, hardness 180-220 BHN
Bonnet	WC9 pressure seal type with graphite seal ring and segmented thrust ring assembly
Wedge	SS316 flexible wedge with Stellite 6 cobalt alloy overlay on seating surfaces
Seat	Integral SS316 with full Stellite 6 hard facing; renewable seat ring optional
Stem	17-4PH precipitation-hardened stainless steel for high-temperature strength and galling resistance
Packing	Graphite braided rings with Inconel wire reinforcement for 593°C superheated steam service
Gaskets	Spiral-wound SS316 + graphite for flanged joints; pure graphite pressure seal ring for bonnet

Testing & Inspection

Test	Requirement
Test Standard	API 598 / ASME B16.34
Certification	CE, PED, ISO 9001, IBR

Applicable Standards

Standard	Description
Design Standard	ASME B16.34 / API 600 / API 602

Notes

Pressure seal bonnet must be re-tightened after first thermal cycle; follow OEM torque sequence provided in installation manual.
WC9 material requires post-weld heat treatment (PWHT) after field welding; maintain 720°C ± 15°C for 2 hours per inch of thickness.
Stellite 6 overlay hardness is 40-45 HRC; do not attempt in-line lapping -- replace trim if leakage exceeds Class V limits.
Flexible wedge design requires minimum differential pressure to seat; not recommended for vacuum or very low-differential service.
IBR Form III-C certificate and third-party inspection by IBR inspector required for boiler application; allow 3 weeks.