EN 593 Lug Type Butterfly Valves

Design Features

Metalsin supplies EN 593 lug type butterfly valves for waterworks projects. The lug butterfly valve is clamped between two pipe flanges of adjacent components when installed. The lug-style body has one integral flange with an identical hole pattern to the piping flanges. The bolt hole on each lug may be either threaded hole or drilled hole. A drilled hole is a through-hole in the lug without threading. When the valve is installed, the connection method is similar to that of a wafer-type butterfly valve, using stud bolts to pass through the bolt holes on the lugs and the two mating flanges on both sides of the valve, secured at both ends with hex nuts. When threaded holes are applied, each hole is tapped from opposite direction, meeting in the center of the hole. Two hex bolts are then inserted through respectively from each mating flange and threaded into the valve’s bolt hole on the lug. Tighten the hex bolts from two sides to secure the entire flanged connection.

Typical bolt hole design for lug type butterfly valves: a) lugs with internally threaded bolt holes; b) lugs with drilled-through bolt holes.

Except for the lug style body design, the EN 593 lug type butterfly valve supplied by Metalsin also features (1) concentric centerline arrangement, (2) rubber seated sealing, (3) ductile iron body, (4) One through shaft or double half-shaft design, (5) various operating configuration (handle, gear, hydraulic, pneumatic, electric actuators), (6) pinned disc, (7) fusion-bonded epoxy coatings on both interior and exterior surfaces according to AWWA C550, (8) ISO 5211 connection pad for actuator attachment, (9) WRAS approved, suitable for water supply pipelines.

Lug Type vs. Wafer Type

Lug type and wafer type butterfly valves differ primarily in their design, installation, and suitability for specific applications. Lug valves, featuring threaded lugs for bolt passages, are easier to install and maintain, offer higher pressure ratings, and are suitable for high-temperature applications, making them ideal for end-of-line service. They are more robust and provide a tighter seal, but are generally more expensive. In contrast, wafer valves, which are sandwiched between pipe flanges without bolt holes, are lighter, more compact, and cost-effective, suitable for lower pressure applications where space is limited. However, they are less suitable for high-temperature applications, more challenging to center, and not recommended for end-of-line service due to their reliance on flange compression for sealing. The selection between the two types depends on factors such as pressure, temperature, cost, and the specific requirements of the pipeline system.

Drawing, Material Specification & Dimensions

The typical photo and drawings for EN 593 lug-type butterfly valves: D-1, for sizes DN40 to DN300; D-2 for sizes DN350 to DN600.