Laux Valve DN800 PN10 double offset butterfly valve features a GGG40 ductile iron body engineered to EN 593 and API 609 standards. The double eccentric (double offset) design separates the disc from the seat during the stroke, dramatically reducing seat wear and operating torque compared to centerline designs — making it the preferred choice for large-diameter water distribution, cooling water, and industrial pipeline service requiring frequent operation and long seat life.
| Parameter | Specification |
|---|---|
| Nominal Size | DN800 (NPS 32") |
| Pressure Rating | PN10 (10 bar / 145 psi) |
| Body Material | GGG40 Ductile Iron (EN-GJS-400-15, equivalent ASTM A536 60-40-18) |
| Design Standard | EN 593, API 609 Category B, GB/T 12238 |
| Face-to-Face | EN 558 Series 13 (double flange) — 390 mm short pattern |
| Flange Drilling | EN 1092-2 PN10 |
| Valve Type | Double Offset (Double Eccentric) Butterfly Valve |
| Operation | Worm Gearbox (standard) / Electric Actuator / Pneumatic Actuator |
| Actuator Interface | ISO 5211 mounting pad (standard) |
| Temperature Range | -10°C to +80°C (NBR) / -10°C to +110°C (EPDM) |
| Leakage Rate | Class VI (bubble-tight) per ISO 5208 |
| Flow Direction | Bi-directional sealing, uni-directional flow preferred |
The double offset butterfly valve derives its name from two deliberate geometric offsets of the stem relative to the sealing surface:
Combined, these two offsets mean the disc contacts the seat only during the final few degrees of closure — the sealing principle changes from "interference sliding" (centerline design) to "cam-action engagement" (double offset design).
| Benefit | Explanation |
|---|---|
| Minimal Seat Wear | Disc separates from seat for 90% of the stroke — no continuous rubbing. Seat life is 3–5× longer than centerline designs. |
| Lower Operating Torque | Friction occurs only at engagement. Torque is typically 30–50% lower than an equivalent centerline valve — smaller actuators required. |
| Frequent Cycling Capability | Ideal for control and modulating applications where the valve cycles daily or hourly. |
| Stable Sealing | Cam action wedges the disc into the seat — sealing force increases with pipeline pressure. |
| Longer Seat Life | Reduced scrubbing extends seat service intervals, reducing maintenance costs on large-diameter valves. |
GGG40 (EN-GJS-400-15) is the European designation for nodular (spheroidal graphite) cast iron with a minimum tensile strength of 400 MPa and 15% elongation. It is the standard body material for large-diameter butterfly valves in water service because:
All GGG40 bodies are coated internally and externally with fusion-bonded epoxy (FBE), minimum 250 μm thickness, RAL 5015 blue. The coating is applied after grit blasting to Sa 2½ surface preparation and is certified for potable water contact.
| Component | Standard Material | Optional Material |
|---|---|---|
| Body | GGG40 Ductile Iron (EN-GJS-400-15) | GGG50 / Carbon Steel WCB / Stainless Steel |
| Disc | GGG40 Ductile Iron + Fusion-bonded Epoxy Coating | Stainless Steel CF8M (316) / Duplex 2205 / Al-Bronze C95800 |
| Stem | Stainless Steel 420 (1.4021) | 17-4 PH / Duplex 2205 / 316 SS |
| Seat Ring | EPDM (vulcanized, dove-tail retained) | NBR / Viton / Neoprene / PTFE |
| Seat Retaining Ring | Stainless Steel 304 | Duplex 2205 |
| Shaft Bearings | PTFE composite (self-lubricating) | Bronze |
| O-Rings | NBR | EPDM / Viton |
| Body Coating | Fusion-bonded Epoxy ≥ 250 μm, RAL 5015 | RAL 5017 / RAL 9005 / custom color |
| Gearbox | Ductile iron housing, IP67 sealed | IP68 submersible / with chainwheel |
| Seat Material | Temp. Range | Best For | Notes |
|---|---|---|---|
| EPDM | -10°C to +110°C | Potable water, raw water, cooling water | Standard choice; WRAS / NSF 61 available |
| NBR | -10°C to +80°C | Oils, fuels, lubricated media | Good hydrocarbon resistance |
| Viton (FKM) | -10°C to +180°C | Chemical media, elevated temperature | Premium option |
| Neoprene | -10°C to +100°C | Seawater, refrigeration | Good all-round marine choice |
| Dimension | Value |
|---|---|
| Nominal Diameter | DN800 (32") |
| Face-to-Face (EN 558 Series 13) | 390 mm |
| Face-to-Face (EN 558 Series 14, long) | 470 mm (on request) |
| Flange Outer Diameter (EN 1092-2 PN10) | 1015 mm |
| Flange Bolt Circle (PCD) | 950 mm |
| Number of Bolt Holes | 24 |
| Bolt Hole Diameter | 33 mm |
| Bolt Size | M30 |
| ISO 5211 Flange | F25 (per actuator selection) |
Exact dimensions confirmed on GA drawing prior to order. Contact Laux Valve for the DN800 GA drawing package.
Every DN800 double offset butterfly valve undergoes the following tests before shipment:
| Test | Standard | Requirement |
|---|---|---|
| Shell Hydrostatic Test | EN 12266-1 / ISO 5208 | 1.5 × PN10 = 15 bar, hold 5 min, zero visible leakage |
| Seat Leakage Test (High) | ISO 5208 Rate A | 1.1 × PN10 = 11 bar, bubble-tight |
| Seat Leakage Test (Low) | ISO 5208 | 0.6 bar, zero leakage |
| Coating Inspection | Factory SOP | Holiday spark test 3 kV, dry film thickness ≥ 250 μm |
| Functional Test | Factory SOP | Full open-close cycle with gearbox, torque verification |
Documentation provided: Test certificate, material certificates (EN 10204 3.1), GA drawing, installation and operation manual.
A centerline butterfly valve keeps the disc in continuous contact with the seat throughout the stroke, causing seat scrubbing and higher torque. A double offset valve moves the stem behind the sealing face, so the disc contacts the seat only during the last few degrees of closing — dramatically reducing seat wear, lowering torque, and extending seat life.
GGG40 (EN-GJS-400-15) nodular cast iron offers 400 MPa tensile strength with 15% elongation — strong enough for large-diameter pressure boundaries yet ductile enough to absorb water hammer. Combined with fusion-bonded epoxy coating, it delivers long service life in water systems at an economical cost.
Yes. The standard ISO 5211 mounting pad accepts worm gearboxes (standard supply), electric actuators (multi-turn or quarter-turn), and pneumatic actuators. We can supply the complete valve-actuator assembly, factory assembled and tested.
Standard configuration (GGG40 body, EPDM seat, gearbox): 4–5 weeks. Custom materials (stainless steel disc, duplex stem, electric actuator): 6–8 weeks. Contact our sales team for a current production schedule.
Each valve ships with a hydrostatic test certificate, EN 10204 3.1 material certificates, GA drawing, and installation/operation manual. Extended documentation packages (MDR, 3.2 certificates, NDE reports) are available for project requirements.
Contact Laux Valve for a quotation on the DN800 PN10 double offset butterfly valve. Please advise seat material (EPDM/NBR/Viton), actuation preference, and delivery destination.
From raw material inspection to final delivery, every butterfly valve undergoes a comprehensive quality inspection to ensure reliable performance and compliance with international standards.
