Alfa Laval LKB-F Butterfly Valve with flange 101,6 mm / 4" – ISO Weld/Weld – HNBR Seal – 304L Stainless Steel. The Alfa Laval LKB-F Butterfly Valve is a hygienic flanged valve designed for easy installation and quick maintenance in stainless steel piping systems. Equipped with ISO weld ends (W/W) and a flanged body, it allows removal without dismantling the entire piping system, reducing downtime and service costs.