L&T Gate, Globe & Check Valves Bolted Bonnet / Cover design 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. he l es e il le ith nged ends o utt weld ends, in pressure ratings from ASME Class 150 to Class 1500, and in a variety of materials of construction. te l es e o e i le edge, outside sce and-yoke and bolted-bonnet construction. The valves conform to API 600. Globe Valves feature a ball-type disc, outside screw-and-yoke and bolted-bonnet construction. They conform to BS 1873 and also meet the general requirements of API 600, including shell wall thickness nd stufing o dimensions Check Valves are of swing-type and bolted-cover construction. They conform to BS 1868 and also meet the general requirements of API 600, including shell wall thickness.