Valves: ball

Ball valves are limited in temperature by the elastomer material used in their seats. Many designs have a secondary metal-to-metal seat to provide a seal in case of fire. Ball valves are not suitable as a throttling valve, but can be used on start-up and shut-down in the partially open position to bleed pressure into or out of a system. 

These valves are the most common general-purpose on/off valves in production facilities. 

150-lb ANSI Non-corrosive service Temperature range -20 to 650°F Maximum pressure Depends on flange rating at service temperature 

Size Ranges General Specifications Platform Service 

Pipe Grade depends on service ASTM A106, Grade B,. Sc,iinlc-sS  

The same options available in plug valves are also available in ball valves except that the size is limited to 6 (15 cm) (see Fig. 8.33). 

The ball valve is not new. It has been around for about 83 yeare. The interest in this type of valve comes from the development of materials to improve sealing synthetic rubber, nylon and fluorinated plastics. The original ball valves were not recommended for bubble-tight service because of the metal-to-metal seat. The new seating materials now provide a tight seal as well as easy operation. 

Decreased maintenance and noncontamination of the fluid stream with lubricants are cited as additional advantages. The valve is cheaper and easier to make than other type valves, and it is easier to obtain a tighter seal with a sphere than with other shapes. Manufacturers have estimated that the ball valve is suitable for one out of five present valve applications. 

Another advantage cited for ball valves is their value for application in remote operation because they open and close so easily with only one quarter turn. With the trend to increased automatic control, this is an advantage indeed. 

The primary use for ball valves in the hydrocarbon processing industry is for valve applications under 400°F and pressures less than 4,000 psi, although with graphite seats they could be operated at temperatures as high as 1,000°F. 

The ball valve is often spring-loaded on the upstream side to compensate for any play that may develop, to insure tight closure at lower differential pressures and to prevent material from getting between the seating surfaces. 

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I, themioelectric cooler J, small ball valves K, levelling device, (reproduced by pemiission from Costigan M... 

In figure 4 is shown how a separatory funnel and a pressure equalized addition funnel are made. The funnel part is just a PP funnel from the grocery store and what it is attached to is a stainless steel ball valve. See how the addition funnel is made by using a rubber stopper and an extra extension of tubing to the top of the funnel Well, that s how one can make a sealed addition funnel out of the ordinary glass separatory funnel that one gets with a distillation kit or from wherever. 

Ball valves in which the ball and seats are inserted from above are known as top-entry ball valves. Replacement of seats is easiest in this... 

For the larger sizes in high-pressure service, the fixed-ball type with O-ring seat seals requires less operating effort. However, these require two different plastic materi s with resistance to the fluid and its temperature. Like plug cocks, ball valves may be either restricted-port or full-port, but the ports are always round and pressure drop is low. 

Aluminum-body diaphragm and ball valves are used extensively. 

For top-feed applications, the most convenient assembly is that shown in Fig. 18-95. The depth of the dam must, of course, be sufficient to contain the total quantity of feed shiny required for the test. Since the test leaf is mounted on top of the vacuum receiver, it is nec-essaiy to provide a valve between the test leaf and the receiver so that the desired operating vacuum may be obtained in the receiver before the start of a test run. It is imperative, however, that there be no restriction in this valve. The preferred choice is a ball valve with the full bore of the drainage piping. 

Gate valves with rising spindles are friendlier than valves with nonrising spindles, as it is easy to see whether they are open or shut. Ball valves are friendly if the handles cannot be replaced in the wrong position. 

Convert quarter turn butterfly valves into ball valves. 

Be sure all ball valves are hill port design. 

Rising spindle valve or ball valve with fixed handle Non-rising spindle valve... 

If relief valves discharge to a common header, it is sometimes convenient to install downstream block valves so that the relief valve can be removed for repairs without shutdown of all equipment tied into the common header. Where either upstream or downstream block valve.s are used they should be full bore gate or ball valves with a device that enables them to be locked open and sealed. These are often referred to as... 

Plug valves usually require lubrication on a regular basis to seal. The> tend to have a more unpredictable torque than ball valves and are thus hard to automate. 

As with ball valves, plug valves are on/off valves and should only be used infrequently in throttling service. They tend to be less e.xpensive than ball valves, but are not as popular because of their need for lubrication. 

Hydrocarbons, Non-corrosive Glycol Ball Valve ANSI 150... 

At high points in piping, vent valves are required to remove air for hydrotesting and for purging the system. At low points, drain valves are required to drain liquids out of the system to perform maintenance. Normally, vent and drain valves are 14-in. or i-in. ball valves. 

Spring-loaded ball valves should be used for drain valves. They have to be held open, and they close automatically if released. The size of drain valves should be kept as small as practicable. With liquefied flammable gases and other flashing liquids, % in. should be the maximum allowed. 

Rodding out narrow bore lines is sometimes necessary. But before doing so, a ball valve or cock should be fitted on the end (Figure 17-lb). It is then possible to isolate the flow when the choke has been cleared, even if the original valve will not close. 

Blowdown Valve Ball Valve Butterfly Valve... 

Valves other than electrically operated (e.g. pneumatically operated ball valves) are equally acceptable if the pressure and closing time requirements of BS 5963 are met. 

Gas does not have the lubricant qualities of fuel oil. Consequently, whereas a drop-weight valve in the oil supply can be expected to close when called upon, this is not the case with a relatively large-bore gas ball valve or plug valve used for gas. 

Boiler or water-heating (kW) Cistern size (1) Ball-valve size (mm) Cold-feed size (mm) Open-vent size (mm) Overflow size (mm)... 

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