Technical Datasheet -- Expanding Gate Valve -- Double Block Bleed WCB

Expanding Gate Valve -- Double Block Bleed WCB

Mechanically Expanding Parallel Disc Isolation Valve for True DBB Service

Document No.SV-DS-GAT-012

RevisionRev A

DateMay 2026

ManufacturerSupreme Valves India, Ahmedabad, Gujarat, India

This datasheet covers expanding parallel gate valves with mechanically expanding discs for true double block and bleed isolation in refinery, LNG, tank farm, and process switching applications.

Technical Specifications

Parameter	Specification
Valve Size Range	DN50 to DN600 (2" to 24")
Pressure Rating	Class 150 / Class 300 / Class 600 / Class 900
Body Material	WCB carbon steel, LCB low-temp, or CF8M on request
Expanding Wedge	SS316 + Stellite 6 hard facing, mechanically expanding parallel discs
Seat Material	Integral SS316 + Stellite 6 overlay, lapped to disc surfaces
Stem Material	SS316 rising stem with ACME threads and thrust bearing
Cam Mechanism	Hardened alloy steel cam and followers for disc expansion/retraction
Packing	Graphite braided rings with anti-extrusion end rings
Gaskets	Spiral-wound SS316 + graphite or RTJ gaskets per pressure class
Temperature Range	-29°C to +425°C (WCB); -46°C with LCB
End Connections	Flanged ASME B16.5, butt weld ASME B16.25
Operation	Handwheel, bevel gear, motorised, pneumatic or hydraulic actuator
Features	Mechanical seal, true DBB, gate retracts, low seat wear, position indicator

Materials of Construction

Component	Material
Body	WCB carbon steel, sand cast, normalised, machined flange faces and seat bores
Bonnet	WCB carbon steel, bolted bonnet with spiral-wound or RTJ gasket groove
Expanding Wedge	SS316 parallel discs with Stellite 6 hard facing, linked by cam-driven expansion mechanism
Seat	Integral WCB with Stellite 6 overlay; renewable seat ring available for severe service
Stem	SS316 rising stem with precision ACME threads, anti-blow-out collar, and handwheel thrust bearing
Cam Mechanism	Hardened alloy steel cam body and followers, lubricated for life with high-temperature MoS2 grease
Gaskets	Spiral-wound SS316 + graphite for standard service; octagonal RTJ rings for Class 600 and above

Testing & Inspection

Test	Requirement
Test Standard	API 598 / ISO 5208 / API 6D (on request)
Certification	CE, PED, ISO 9001, API 6D monogram on request

Applicable Standards

Standard	Description
Design Standard	ASME B16.34 / API 600 / BS 1414

Notes

Expanding gate valves require periodic inspection of cam mechanism and lubrication; service interval is 2 years or 5,000 cycles, whichever occurs first.
Cam mechanism is factory-lubricated with high-temperature MoS2 grease; do not substitute with standard lithium grease which degrades above 150°C.
True DBB requires body bleed valve; specify integral needle bleed or separate NPT connection at order.
For cryogenic service below -46°C, specify LCB body, SS316 trim, and extended bonnet with low-temperature packing.
Seat lapping is performed as a matched assembly; do not interchange discs or seats from different valves.