Globe valve

The conventional globe valve offers a considerable resistance to flow. The angle valve and the Y valve were developed to reduce that resistance. Angle valves are not used extensively because the 90° bend in process piping would subject the valves to considerable stress. 

Full bore tfvough-corxkjit design elirrurtales turbulence. Pressure drop ii rvi greater than Ihrough an equal ler ih ol pipa. 

Seal faces are protected Iron How m both fully open and fully closed positK ns Seats have TFE inserts, providing bom a TFE-io-meial and a metal-ichmeial seal 

Globe valves have metal-to-metal seats, which are easy to replace. Because of the erosive action of the fluid when the valve is throttling, they should not be used for on/off service. A tight seal may not be possible. 

Fiqure 15-5. Cutaway view of globe vdve. (Courtesy of Jenkins Bros.) 

There are many configurations of plugs and seats ( trim ) that create different control responses. The design specification of control valves is beyond the scope of this book. 

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A mixing valve in the form of a conventional globe valve is simple and economical. A typical service iavolves caustic washing of gas oil and water—oil mixing upstream of a desalter. The valve is normally specified to handle a pressure drop ia the range of 20—350 kPa (0.2—3.5 atm). 

Fig. 2. (a) Gate valve (b) plug valve and (c) globe valve. 

Gate valve Globe valve Check valve Angle valve... 

The plug, cage, seat ring, and associated seals are laiovvn as the trim, A kev feature of globe valves is that thev allow maintenance of the trim via a removable bonnet without removing the valve bodv from the line. Bonnets are tvpicallv bolted on but rnav be threaded in smaller sizes. 

Pressure drop through globe valves is much greater than that for gate valves. In Y-type globe valves, the stem and seat are at about 45° to the pipe instead of 90°. This reduces pressure drop but impairs ahgnment of seat and disk. 

Globe valves in horizontal lines prevent complete drainage. Seat-wiper valves in which the disk may be rotateci by a separate stem inside and concentric with the main stem are used to clear the seats of solid deposits. 

Cast-iron flanges (ANSI B16.1, 125-lb bolt spacing) are permanently attached to the porcelain with high strength acid-resistant cement. Flanged chemical-porcelain 90° and 45° elbows, tees, crosses, reducers, caps, and globe valves of the Y pattern are available. Armored chemical porcelain is furnished with 1.5- to 2.4-mm- (Mfi- to... 

Convert globe valves into gate valves if possible. 

This system piping uses fittings with bolted Ilanges, see Figure 8-5. The 6 inch elbows have a eonstant (K value) of 0.280. The 4 inch elbows have a K value of 0.310. The 6 inch gate valves have a K value of 0.09. The 4 inch gate valves have a K value of 0.15. The 4 inch globe valve... 

There are 5 valves in all. There are two 6 ineh gate valves in the siietion pipe. There is a 4 ineh gate valve, a 4 inch globe valve, and a 4 ineh cheek valve in the discharge pipe. The formula is ... 

Mixing Valve This type of mixing device is normally a manually operated globe valve operated at 20 to 350 kPa pressure drop. Common use of this device in refinery operations is for water and crude oil mixing before a desalter and in caustic scrubbing operations. 

Globe valve, open 9.7 90° double-miter elbow 0.59... 

A type of miniature globe valve, needle valves are used in instrument systems for throttling of small volumes. They have metal to metal seats, but due to the small size, can be used for positive shut-off (Figure 15-8). Needle valves have small passageways that may plug easily and limit their use to very small flow rates. 

Investigation showed that the pressure drop through the trip valve—a globe valve—was so high that the valve eould not elose against it. There was a flow eontrol valve in series with the trip valve (Figure 14-1), and the trip nonnally elosed this valve as well. However, this valve failed in the open position—this was the reason for the high temperature in the reactor—and the full upstream pressure was applied to the trip valve. 

Valves have two main functions in a pipeline to control the amount of flow, or to stop the flow completely. There are many different types but the most commonly used are the gate valve and the globe valve. The gate valve contains a disk that slides at right angles to the flow direction. This type of valve is used primarily for on-off control of a liquid flow. Because small lateral adjustments of the disk cause e.xtreme changes in the flow cross-sectional area, this type of valve is not suitable for adjusting flow rates. 

Gale valve or globe valve Fool valve... 

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