Bellows Sealed Valve Vs. Conventional Valve

Conventionally globe valve used  in steam line uses gland packing. Instead of Gland packing The Bellows Sealed valve is consisting of  a bellows cartridge welded to the valve bonnet and stem. There is only a Gasket joint in the valve body and globe site only. So there is Little possibility to leak steam. What is bellows- A device with concertinaed sides to allow it to expand and contract.  As the valve stem strokes, the bellows expands or compresses with the stroke movement. Advantages of using Bellows sealed valve- Thought the initial cost of the bellows sealed valve is high with compare to conventional globe valve but with compare to maintenance and overhead costing is less. For a maintenance Engineer to select a bellows sealed valve instead of conventional valve is a good decision and he/she will be trouble free for a long time. Many factories where steam consumption in the floor is high, there multiple number of valves is needed and in conventional valves (Gland packed seal valve/piston ring valves) maximum times after a short time interval the gland packing leaked. As  a result it looks odd, time consuming to replace valves, Production hampered , risky. 

Source: http://industrialexp.blogspot.com/