Lug butterfly valves are mounted between two pipe flanges using bolts that pass through threaded inserts, or lugs, extending from the valve body. This design features separate sets of bolts on each side of the valve without the use of nuts, allowing the valve to function as an isolation valve or be installed in end-of-line applications. This setup enables maintenance on one side of the valve without affecting the other side, thereby reducing downtime.
However, lug butterfly valves must support additional loads, as the weight of the pipeline is distributed across the valve body. Typically, the pressure rating of these valves may be reduced when used in end-of-line service due to the lack of a downstream flange to help secure the seat in place. This can lead to seat deformation and potential leakage as the media may push past the disc and seat seal.
Features of this type of butterfly valve is as following:
-construction: Reinforced body, multiple lugs
– Installation: bolted via luges
– sealing: single, double seats
– pressure rating: vacuum to 16 bars
– Temperature range: -20 to 90°c
– Applications: Industrial pipeline
– Advantages: Flexible installation
– Disadvantages: Heavier, costlier