The api 600 bs 1873 bs 1868 family of l&t gate, globe and swing check valves is exceptionally sturdy, rugged and durable, with a reputation for quality, integrity and long service. They are designed for tight sealing and ease of operation. The valves are available with flanged ends or butt- weld ends, in pressure ratings from asme class 150 to class 1500, and in a variety of materials of construction. gate valves are of flexible wedge, outside screw- and-yoke and bolted-bonnet construction. The valves conform to api 600.