The main challenges in fabricating lug butterfly valve include:
Ensuring tight shutoff and low leakage.
The mating surfaces of the disc and seat have to be machined precisely to achieve good sealability.
Achieving even wear.
The disc has to rotate uniformly on the shaft without wobble to ensure even wear of the sealing surfaces. This requires high concentricity and runout tolerances.
Accommodating high torque.
The shaft, bearings and other components have to be robust enough to transmit the high torque required to open and close the valve.
Preventing galling.
The contact surfaces have to have suitable finish and metallurgy to prevent galling during high torque operation.
Achieving buffering.
Shock absorbers or cushions are sometimes included to prevent impact at the end of open and close strokes.
Ensuring structural integrity.
The valve has to withstand the high pressures in the line without deformation or damage. Thick sections and reinforcement ribs are used.
Facilitating manual or automated operation.
The valve has to have suitable flange and actuator connections for the intended mode of operation.
Ensuring durability.
In addition to high strength, the materials and design have to ensure a long fatigue life and resistance to wear, corrosion and temperature effects.
Meeting specifications.
The valve has to meet tight requirements on size, pressure rating, material grades, temperatures, seat leakage, etc. as per the specifications.