Views: 0 Author: Site Editor Publish Time: 2021-03-17 Origin: Site
1. The double block and bleed valve have evolved to replace and add the process of bolting together individual valves to make the valves in one body .it saved a lot of space and material.
2. Special designs including injecting quills ,sample probes ,double block and single block, in-built check valves and seat wipers.
3. Dual isolation is necessary requirement when maintenance is taking place down stream of the first isolation valve. Cavity venting is provided by either a ball or globe OS&Y vent valve so that trapped pressure between the two isolation valves is safely vented.
4. These valves have also evolved to encompass the function of chemical injection (using a suitable quill) and sample points .In-built check valves are often integrated in these valves.
5. Fire Safe according to BS6755/API 6FA/API 607, since each sealing point is provided by a secondary fire-safe seal in graphite. Valve soft seats also are provided with secondary metal-to metal seal in case of fire.
6. Valve design can be either Trunnion or floating type ,anti blow -out stem and typically SPE seat design .Drain port is normally provide with a floating ball valve ,to be fitted with final user drain line .valve seats can be soft or metal to metal hard-faced.
