DIN Standard Metal Hard Sealed Triple Offset Flanged Butterfly Valve

The DIN standard metal hard sealed triple offset flanged butterfly valve is an industrial isolation valve engineered for high-temperature steam, thermal oil, process gas and abrasive slurry lines where resilient soft seats cannot maintain long-term sealing integrity. Manufactured by Trekre Valve in Wuxi, China, this double-flange triple eccentric butterfly valve follows German DIN and European EN design practice for face-to-face dimensions, flange drilling and shell testing, while applying three-offset disc geometry and metal-to-metal sealing for bubble-tight shut-off across demanding thermal and chemical duty. Worm gear, bare stem or actuator-ready configurations suit manual plant isolation, remote motorisation and quarter-turn automation on refinery, power generation and district heating networks.

German-standard metal hard sealed flange butterfly valves occupy a distinct position between conventional double-eccentric soft-seated designs and fully engineered triple-offset valves for critical isolation. Trekre configures the body with EN 558 face-to-face lengths, EN 1092-1 or DIN PN10/PN16/PN25/PN40 flange faces and EN 593 type testing but replacement suitability requires comparison of the exact flange facing and drilling, face-to-face dimensions, bore and disc clearance, operator space and any required adapters with the existing installation. The triple offset disc path lifts the sealing surface away from the seat during the opening stroke, minimising friction, reducing operating torque and extending seat life on valves that cycle frequently or remain closed under high differential pressure for extended periods.

DIN metal hard sealed triple offset flanged butterfly valve construction

Connection type: double flange (flanged ends both sides)

Structure: triple eccentric (triple offset) metal hard sealed disc

Size range: NPS 2″ to 48″ (DN50 to DN1200)

Pressure rating: DIN PN10, PN16, PN25, PN40; ANSI Class 150/300 where cross-referenced

Body material: WCB carbon steel, WC6/WC9 alloy steel, CF8/CF8M austenitic stainless steel, LCB low-temperature carbon steel

Disc material: stainless steel 304/316 or alloy matched to body and media, with hardened sealing edge

Seat: metal seated — Stellite-faced integral body seat, replaceable metal ring or multi-layer laminated hard seal

Operation: worm gear manual standard; bare stem ISO 5211 platform; electric multi-turn or pneumatic quarter-turn optional

Seal direction: bidirectional or unidirectional per pipeline specification

Design standard: DIN 3354, EN 593, EN 12266-1, API 609 Category B where applicable

End flange: EN 1092-1 Form B/C, DIN PN10/PN16/PN25/PN40

Face-to-face: EN 558 Series 13/14, DIN 3202 F1/F4 tables

Testing: EN 12266-1 shell and seat, API 598, DIN 3230 leakage class

Temperature range: -29°C to 425°C (body, seat and packing limited by material selection)

Triple offset geometry and metal hard sealing

Conventional concentric or double-eccentric butterfly valves rely on elastomer liners or PTFE seats that degrade under steam temperatures above 200°C, oxidising process gases and abrasive particulates in slurry service. The triple offset path creates a conical closure line where disc and seat contact occurs only in the final degrees of stroke, producing a camming action that wipes the sealing surface clean while avoiding the continuous sliding wear typical of lined discs. Trekre selects Stellite overlay, nickel-base alloy or multi-layer elastic metal seals depending on shut-off class, differential pressure and media corrosivity required by the project specification.

For saturated steam, thermal oil and other process duties, confirm the selected seat construction, operating conditions and agreed shutoff test and acceptance requirements. Metal hard sealing alone does not establish a zero-leakage guarantee across different services. The disc stem offset, seat cone angle and body seal ring geometry are calculated to maintain uniform contact pressure across the full bore range from DN50 branch lines to DN1200 main headers, keeping breakaway torque predictable for worm gear sizing and actuator selection. Fire-safe configurations with secondary metal backup and graphite packing are available for refinery and petrochemical zones subject to API 607 or EN ISO 10497 requirements.

DIN and EN compliance for European and export projects

European process plants, municipal utilities and OEM skids frequently specify DIN 3354 butterfly valves with EN 1092-1 flange connections and EN 558 dimensional tables to simplify interchangeability with existing German and Central European valve populations. Trekre manufactures this triple offset flanged butterfly valve family with documented compliance to EN 593 type testing, material certificates per EN 10204 3.1 and dimensional inspection against EN 558 Series 13 short or Series 14 long face-to-face lengths. Flange drilling covers PN10 through PN40 pressure stages with raised face or flat face options matched to gasket selection in the piping specification.

For export projects referencing both DIN and ANSI standards, Trekre provides cross-reference datasheets mapping EN PN classes to ANSI Class 150/300, face-to-face equivalency and actuator mounting per ISO 5211. Bare stem high-platform configurations accept direct-mount electric actuators, pneumatic scotch-yoke operators and chain-wheel extensions for elevated or remote installations without modifying the valve body or flange dimensions specified in the contract drawings.

Drive options and operating characteristics

Manual worm gear operation is the standard configuration on DIN metal hard sealed triple offset flange butterfly valves above DN150, providing torque multiplication, self-locking position hold and position indication at the gear head. Smaller bore valves may be supplied with hand lever or gear operator depending on differential pressure and user preference. The ISO 5211 mounting pad on bare stem variants allows direct coupling to multi-turn electric actuators for remote valve stations, pneumatic actuators with scotch-yoke torque output for fast emergency isolation, and hydraulic operators on subsea or high-pressure test skids.

Low operating torque from triple offset geometry reduces gear box size and actuator cost compared with double-eccentric metal-seated designs that depend on line pressure to energise the seal. Trekre publishes torque curves at rated pressure, breakaway and running values, to support actuator sizing per IEC 60534 or vendor-specific safety factors. Position feedback switches, mechanical position indicators and extension stem arrangements are integrated at the factory to minimise field assembly on tight schedule projects.

Product parameters summary

Structure: triple eccentric double-flange body with metal hard sealed disc

Nominal diameter: DN50–DN1200 (2″–48″)

Pressure class: DIN PN10/PN16/PN25/PN40; ANSI Class 150/300 optional

Body: WCB, WC6, WC9, CF8, CF8M, LCB

Disc: stainless or alloy with hardened sealing surface

Seat: Stellite, multi-layer metal or elastic metal ring hard seal

Operation: worm gear manual; bare stem ISO 5211; electric or pneumatic optional

Connection: double flange per EN 1092-1 / DIN

Design standard: DIN 3354, EN 593, EN 12266-1

Temperature range: -29°C to 425°C

Testing: EN 12266-1 / API 598 / DIN 3230

Typical applications and industries

Saturated and superheated steam isolation on power plant boiler feed, extraction and bypass headers

Thermal oil, heat transfer fluid and hot water circuits in chemical and pharmaceutical processing

Refinery and petrochemical process lines on catalytic, hydrotreating and distillation branches

District heating transmission and substation isolation on high-temperature water networks

Pulp and paper black liquor, white liquor and steam utility isolation points

Metallurgical off-gas, coke oven gas and high-temperature exhaust ducting with flanged spool connections

Industrial HVAC and central plant chilled/hot water headers requiring metal-seated fire-safe isolation

Advantages of Trekre DIN triple offset flange butterfly valves

Triple offset metal hard sealing delivers reliable shut-off on steam and high-temperature media where soft seats fail prematurely, reducing unplanned shutdowns and seat replacement cost over the plant lifecycle. DIN and EN dimensional compliance simplifies substitution into European specifications without custom adapter flanges or non-standard face-to-face lengths. Flanged ends on both sides integrate directly with EN 1092-1 mating flanges, blind flanges and spectacle blinds on isolation and maintenance stations. Material options from carbon steel through alloy and stainless cover the majority of process temperature and corrosion requirements within one product family. Factory shell and seat testing per EN 12266-1, material traceability and dimensional reports support QA audits, CE marking documentation and third-party inspection on EPC contracts. Trekre Valve provides technical datasheets, torque tables, actuator interface drawings and maintenance instructions from our Wuxi manufacturing facility for distributor stocking, OEM integration and project procurement.

Every DIN standard metal hard sealed triple offset flanged butterfly valve undergoes hydrostatic shell and seat testing, dimensional verification against EN 558 tables and final inspection before shipment. Contact Trekre for selection assistance on pressure class, seat architecture, actuator mounting and compliance with DIN, EN or cross-referenced ANSI standards on your process isolation application.