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Industriearmaturen Lug Butterfly Valves

Lug Butterfly Valves in GGG40 & Stainless Steel — Buy Online

Lug butterfly valves in ductile iron GGG40 or stainless steel 1.4408, EPDM, NBR or FKM/Viton seat, DN40 to DN500, PN10/PN16. Suited for dead-end and downstream service.

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Lug Butterfly Valves
  • Flanged Butterfly Valve Type AK201

    Flanged Butterfly Valve Type AK201

    Sizes: DN50–DN600

    Flange connection: PN10, PN16

    Case material: Ductile Iron GGG40

    Flap seal: EPDM, NBR, FKM (Viton)

    Operations: Electric, Pneumatic Double-Acting & Single-Acting, Hand Lever (ISO 5211), Gearbox

  • Flanged Butterfly Valve Type AK211

    Flanged Butterfly Valve Type AK211

    Sizes: DN25 – DN1000

    Flange connection: PN10, PN16

    Case material: GJS400, WCB (1.0619), CF8M (1.4408), Bronze, Aluminum

    Flap seal: EPDM, NBR, Viton (FPM), Viton Bio, Silicone, Hypalon

    Operations: Electric, Pneumatic double-acting & single-acting, Hand lever, Gearbox

  • Flanged shut-off butterfly valve for gas AK211G

    Flanged shut-off butterfly valve for gas AK211G

    Sizes: DN25 – DN600

    Flange connection: PN10, PN16

    Case material: GGG40 + epoxy 120 µm GJS400

    Flap: GJS400, CF8M (1.4408)

    Operations: Electric, Pneumatic double-acting & single-acting, Hand lever, Gearbox

  • Stainless steel butterfly valve AK203

    Stainless steel butterfly valve AK203

    Nennweite: DN50 – DN300

    Flange connection: PN10, PN16, ANSI 150

    Case material: Stainless steel (1.4408)

    Flap seal: EPDM

    Operations: Electric, pneumatic double-acting & single-acting, hand lever, gearbox

  • PTFE butterfly valve, flanged type AK131

    PTFE butterfly valve, flanged type AK131

    Nominal diameter: DN50 – DN300

    Flange connection: PN10, PN16, Optional Flanschbohrung 150lbs

    Case material: EN-GSJ-500-7 (GGG50) spheroidal graphite cast iron

    Flap seal: PTFE

    Operations: Electric, Pneumatic double-acting & single-acting, Hand lever, Gearbox

  • Double-eccentric butterfly valve type AX131

    Double-eccentric butterfly valve type AX131

    Connection: PN10, PN16, ANSI 150 (on request)

    Face-to-face: EN 558-1, Series 20; ISO 5752 Series 20

    Tightness class: Class V / ISO 5208, leakage rate AA

    Body: ASTM A351 CF8M, ASTM A216 WCB

    Zulassung: TA Luft (ISO 15848), ATEX according to 2014/34/EU – Atex II 2GDc

Produktübersicht

Lug Butterfly Valves: Independently Bolted Shut-Off for Dead-End Service

A lug butterfly valve — often called a flanged butterfly valve in Europe — carries threaded lugs cast into the body, so each side of the pipeline is bolted to the valve independently. The downstream flange can be removed for maintenance or for a blind-flange changeover while the upstream side remains pressurised and sealed. Consequently the lug design is the mandatory choice for dead-end service and for any position where one line has to be isolated without dismantling the other.

Fergo supplies the lug range in the AK201 standard series with an EPDM, NBR or FKM/Viton seat, and in the DVGW-certified AK211G for gas and AK211W for drinking water. Bodies are either ductile iron GGG40 with a 150 µm epoxy coating or, for the stainless AK211G variant, CF8M / 1.4408 with an AISI 316 shaft. Discs are stainless steel 1.4408 and shafts AISI 420. Nominal sizes cover DN40 to DN500 at PN10 and PN16, face-to-face lengths follow EN 558-1 Series 20, flange dimensions comply with EN 1092-1 and actuator mounting flanges meet ISO 5211.

Lug butterfly valves serve pump isolation in water and wastewater plants, dead-end service in fire protection risers, drinking water pumping stations, gas distribution branches, chemical dosing systems, HVAC and district heating circuits. Operators choose between an aluminium hand lever, a gearbox, a pneumatic actuator or the J4C electric actuator. Where both pipe ends stay permanently installed, the more economical wafer butterfly valve covers the same nominal sizes, and for severe pressure and temperature the double-eccentric butterfly valve range provides the high-performance alternative.

Subcategories: Lug Butterfly Valves by Seat and Certification

01 AK201 — Standard Lug Butterfly Valve (EPDM / NBR / FKM)

The AK201 lug butterfly valve is the flagship of the range. Body in ductile iron GGG40 with a 150 µm epoxy coating, disc in stainless steel 1.4408 / CF8M and shaft in AISI 420. The seat ring is available in EPDM for water and dilute alkalis, NBR for oils and hydrocarbons or FKM/Viton for aggressive chemicals and elevated temperatures. Nominal sizes span DN40 to DN500 at PN10 and PN16, and every variant accepts a hand lever, a gearbox, a pneumatic actuator or an electric actuator through the ISO 5211 mounting flange. The threaded lugs allow bolted assembly from either side, so the valve can serve as an end-of-line shut-off without an additional blind flange.

 

 

02 AK211G — DVGW Gas Lug Butterfly Valve

The AK211G lug gas butterfly valve carries the DVGW Gas approval to DIN EN 13774 for fuel gases under DVGW-Arbeitsblatt G 260. The GGG40 body is finished with an epoxy coating, the disc is stainless steel 1.4408 and the seat ring is NBR — the mandatory elastomer for DVGW gas service. Operating range covers −20 °C to +60 °C at PN10 or PN16 across DN40 to DN500. Because the lug body allows independent bolting on each side, the AK211G is the preferred design for gas branch lines that terminate at a meter, a burner skid or a shut-in valve.

03 AK211W — DVGW Drinking Water Lug Butterfly Valve

The AK211W lug drinking water butterfly valve holds the separate DVGW drinking water approval. The EPDM seat ring is tested against DVGW-Arbeitsblatt W 270 for microbiological suitability in potable water contact, and the body coating is approved for drinking water service. Stainless steel 1.4408 keeps the disc corrosion-resistant, and an epoxy-coated GGG40 disc with Resicoat R4 is available as an economical alternative for large nominal sizes. Standard applications include pump isolation, reservoir outlets and treatment plant branches where dead-end shut-off is required.

04 AK211G — Stainless Steel Lug Butterfly Valve (CF8M Variant)

For coastal, marine or chemically loaded atmospheres the AK211G is also available in a full stainless steel version. Body and disc are CF8M / 1.4408, the shaft is AISI 316 and the seat ring remains NBR with DVGW Gas approval. Because the molybdenum-alloyed stainless steel resists atmospheric chloride corrosion without any coating, this stainless steel lug butterfly valve is the preferred choice for salt-air installations, offshore gas skids and industrial sites near the coast — situations where a coated cast iron body would need repeated repainting to stay in service. Operating pressure PN10.

Materials in Detail: Specifying the Right Lug Butterfly Valve

Body Materials — GGG40 or Stainless Steel

1. Ductile Iron GGG40 / EN-GJS-400-15 with Epoxy Coating 150 µm (Standard Body)

Application: water supply, wastewater, HVAC, cooling water, fire protection, gas distribution, drinking water networks and general industrial pipework — the standard body across every AK201, AK211G and AK211W variant

Temperature: up to +120 °C with an EPDM seat · gas −20 °C to +60 °C with NBR · PN10 and PN16

Advantages: high toughness and vibration damping, economical up to DN500, the 150 µm epoxy layer resists corrosion in atmospheric and immersed service, threaded lugs cast integrally with the body ensure high pull-out strength for dead-end installations

Limitations: not suitable for permanently chloride-rich, saline or aggressive chemical media; coating may be damaged if not handled carefully during installation

2. Stainless Steel CF8M / 1.4408 (AISI 316) with AISI 316 Shaft

Application: the AK211G is offered as a full stainless steel lug butterfly valve for coastal and marine gas installations, industrial gas skids near saline air, chemical processing branches and any environment where external corrosion of a coated cast iron body would shorten service life

Temperature: −10 °C to +90 °C with an NBR seat · PN10

Advantages: molybdenum content resists pitting from chlorides and salt spray without any coating, no maintenance of the paint finish, hygienic external surface, single-material construction across body, disc and shaft, longer service life in aggressive atmospheres

Limitations: higher material cost than GGG40 — specify only where the external or internal environment genuinely justifies stainless steel

Disc Materials

1. Stainless Steel 1.4408 / CF8M (Standard Disc)

Application: standard disc across every AK201, AK211G and AK211W variant for water, gas and general process duty

Temperature: matches the seat envelope

Advantages: molybdenum content resists pitting and crevice corrosion, no metal-ion pickup into drinking water, dimensionally stable under bolt load, hygienic surface

Limitations: higher cost than a coated GGG40 disc, which is the economical alternative for large-bore drinking water lines

2. Ductile Iron GGG40 with Resicoat R4 Epoxy Coating (Drinking Water Variant)

Application: economical disc alternative in the AK211W drinking water variant for cold and warm potable water at large nominal sizes

Temperature: 0 °C to +70 °C

Advantages: Resicoat R4 is a fusion-bonded epoxy specifically approved for potable water contact, no metal-water interface, more economical than the stainless steel disc from DN200 upwards

Limitations: coating requires careful handling during installation to avoid mechanical damage; not intended for abrasive or chemically aggressive water

Certificates & Standards for Lug Butterfly Valves

Fergo lug butterfly valves comply with the Pressure Equipment Directive 2014/68/EU and carry the CE mark. Gas versions AK211G hold the DVGW Gas approval to DIN EN 13774 for fuel gases under DVGW-Arbeitsblatt G 260, and drinking water versions AK211W carry the separate DVGW drinking water approval, with the EPDM seat verified against DVGW-Arbeitsblatt W 270 for microbiological suitability in potable water contact. Flange dimensions follow EN 1092-1 and ANSI Class 150, face-to-face lengths follow EN 558-1 Series 20, and actuator mounting flanges meet ISO 5211.

Two international standards are of particular relevance to lug butterfly valves in dead-end service. MSS SP-67 sets the design, testing and marking requirements for butterfly valves in general industrial applications, including the lug design used at end-of-line positions, and AWWA C504 covers rubber-seated butterfly valves specifically for water works service — Fergo’s AK201 with an EPDM seat aligns with the AWWA C504 material and construction philosophy for potable water pumping stations. Inspection documents to EN 10204 — the type 2.2 works certificate or the type 3.1 inspection certificate — are available on request. A full overview of all certificates is published on the Fergo certificate page. You can verify seat and body compatibility with your medium beforehand using the Fergo resistance check.

Delivery & Availability

Fergo holds more than 25,000 industrial valves in stock. Lug butterfly valves in the AK201 standard series and the DVGW-certified AK211G and AK211W series are available in every common nominal size from DN40 to DN500, in every seat material and in every actuation type. Automation is carried out in-house with a gearbox, a pneumatic actuator or the J4C electric actuator, so a pneumatic lug butterfly valve or an electrically actuated version leaves the warehouse fully assembled and tested. A Switchmaster limit switch box provides visual and electrical position feedback for automated packages.

Fergo ships across Europe — including the United Kingdom, the Nordic countries and all other EU member states. Smaller lug sizes travel by parcel service, whereas large-bore lug valves for water utilities, gas grids and industrial branches go by forwarding agent. Express shipping delivers within the next working days. You will find shipping costs, payment options and express terms on the shipping and payment terms page. For special seat compounds, alternative disc coatings, PFA-lined lug designs or complete automation packages, please see the PFA-lined butterfly valve range or contact us through the customised solutions section.