What is the criteria used when selecting a ball or globe valve in the piping system of propane bulk storage installation? Such valves would be 2", 2-1/2" and 3" size fitted in the liquid and vapor transfer lines (loading and unloading). Just speaking about isolating valves (on-off) the globe valve is at a disadvantage on almost every parameter. Shutoff: a metal-seated globe valve will require use of a cheater to torque the seats together. Ball valves can be expected to have resilient seats and to shut off tightly. Convenience: Globe valve requires 4 or 5 turns of the handwheel to open or close. Ball valve: 90-degrees. (Ball valves were initially developed for USNavy. Tactical advantage to being able to yank a valve shut while at a dead run, vs having to stop and grind away at a handwheel.) Somebody over-eager to close a ball valve may yank it shut too quickly and cause liquid-hammer. In fairness: Larger ball valves need a gear-operator. Position of a ball valve is easy to read. Lever is aligned with the pipe when the valve is open. Position indication of a globe valve is on a small plate inside the yoke. Environmental: Rising stem in globe valve drags packing particles out, and environmental dirt in, every time the valve is cycled. ALso if you figure 4 turns to open, globe valve packing sees 16 times the wear on each stroke. Ball valve packing stays tighter-longer. Installation: Globe valve is taller and heavier and usually longer F-F, than a ball valve of the same size. I started to say something about Globe valves having a fire-safe advantage, but ball valves are offered in firesafe meeting API standards. Capacity: Globe valves have a convoluted s-shaped flow path. Ball valves are straight through. Even a "regular" port ball valve has no more friction loss than an elbow, while "full" port ball valves have loss no gtrater than an equivalent length of straight pipe-probably less since the ball is machined to better surface finish than the inside of the pipe.

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